Weather

=AVIATION WEATHER=

GENERAL STRUCTURE OF THE ATMOSPHERE
ELO 2.1 Describe the characteristics of the troposphere, tropopause, and the stratosphere.

TROPOSPHERE TROPOPAUSE STRATOSPHERE ELO 2.2 Describe the flight conditions associated with the troposphere, tropopause, and the stratosphere. TROPOSPHERE TROPOPAUSE STRATOSPHERE ELO 2.3 Identify the six weather elements a pilot may encounter. ELO 2.4 Identify the six primary hazards to flight. TURBULENCE THUNDERSTORMS WIND SHEAR ICING LOW CEILINGS LOW VISIBILITY
 * Adjacent to the earth’s surface
 * Varies in height from an average of 55,000 feet over the equator to 28,000 feet over the poles
 * Averages 36,000 feet over the United States
 * Temperature decreases with increasing altitude
 * Contains large amounts of moisture and condensation nuclei due to proximity to earth’s surface
 * Upper boundary is the tropopause, marked by an abrupt change in the rate of the temperature decrease with increasing altitude
 * Transition zone between the troposphere and the stratosphere
 * Temperature is isothermal with altitude
 * Winds normally increase in speed with altitude below the tropopause
 * Contrails frequently form and persist near the tropopause since it is normally the coldest area in the lower atmosphere
 * Water vapor and large scale vertical currents do not exist to any extent in the tropopause
 * Increasing temperature with increasing altitude due to the presence of ozone gas
 * Thin air offers little resistance to aircraft
 * Lack of weather makes for outstanding flying
 * Above the stratosphere are the mesosphere thermosphere
 * Turbulence due to the increasing wind speed with increasing altitude
 * Storms are present and can limit visibility
 * Turbulence due to the increasing wind speed with increasing altitude
 * Contrails are often present
 * Excellent conditions with maximum visibility and very little resistance to the aircraft
 * Lack of weather makes this the best flying level
 * Temperature
 * Atmospheric pressure
 * Wind
 * Humidity
 * Clouds
 * Precipitation
 * Comes in many forms and can be dangerous to flight
 * Pilot may not be able to control aircraft due to being violently "bounced" around the cockpit
 * Structural damage may also occur to aircraft
 * Contain all hazards in one package
 * Extensive damage to aircraft
 * Loss of communications due to damaged antennae
 * Altered airfoils to the point of producing entirely different flight characteristics
 * Low ceilings and low visibility accompany these storms
 * Turbulence may be found with wind shear as well as outside the storm in close proximity and with microbursts
 * Lighting can damage or explode the aircraft
 * Icing should be expected
 * Movement of air at different velocities in the same or opposite directions
 * Causes changes in aircraft performance that can have disastrous results
 * Microbursts, strong downdrafts, are most dangerous and are especially dangerous during low and slow flight such as take-off and landing
 * Ice build-up adds to the weight of the aircraft and changes the shape of the airfoil
 * Ice build-up on the pitot tube causes inaccurate air speeds
 * Ice build-up on the static pressure ports can cause inaccurate altimeter, vertical velocity, and airspeed readings
 * Make approaches to land hazardous or even impossible
 * May cover areas so large that fuel becomes a consideration
 * If a pilot flies below the ceiling he may crash into the ground or some other obstacle
 * Often associated with low ceilings
 * May be caused by smoke, haze, dust, and fog even with no low clouds present
 * May make landings hazardous or impossible

ATMOSPHERIC TEMPERATURE AND PRESSURE
ELO 2.5 Define specific heat and how it effects the warming of the earth. ELO 2.6 State the primary source for all weather. ELO 2.7 Define lapse rate. ELO 2.8 State the average lapse rate in degrees Celsius ELO 2.9 List and define the lapse rates: steep, shallow, isothermal, and inversion relative to the standard lapse rate. STEEP LAPSE RATE SHALLOW LAPSE RATE ISOTHERMAL LAPSE RATE INVERSION ELO 2.10 Define atmospheric pressure. ELO 2.11 State the standard units of pressure measurement. ELO 2.12 Differentiate between sea level pressure and station pressure. SEA LEVEL PRESSURE STATION PRESSURE ELO 2.13 Define the standard atmosphere to include temperature and pressure. ELO 2.14 List the major items found on the surface pressure/analysis chart. ISOBARS HIGH LOW RIDGE TROUGH ELO 2.15 Explain pressure gradient. ELO 2.16 Define indicated altitude, calibrated altitude, MSL (Mean Sea Level) altitude, and AGL (Above Ground Level) altitude, pressure altitude, and density altitude. INDICATED ALTITUDE CALIBRATED ALTITUDE MSL (MEAN SEE LEVEL) ALTITUDE AGL (ABOVE GROUND LEVEL) ALTITUDE PRESSURE ALTITUDE DENSITY ALTITUDE ELO 2.17 Describe the effects of pressure changes on aircraft altimeters. ELO 2.18 State the effects of temperature deviations from the standard lapse rate on aircraft altimeters. ELO 2.19 Calculate the MSL altitude, AGL altitude, and the altimeter error resulting from a change in atmospheric pressure.
 * Specific heat is the amount of heat required to raise the temperature of one gram of a substance one degrees Celsius
 * Specific heat of an object is constant
 * A land surface will heat up and cool much faster and to a much greater extent than will a water surface
 * Specific heat of water is four times that of most land surfaces
 * Insolation is the primary source for all weather phenomena on earth
 * Insolation is the total radiation reaching the earth’s surface
 * Insolation ceases at night and is replaced by terrestrial radiation which cools the earth thus maintaining the heat balance
 * Lapse rate is the change in atmospheric temperature with increasing altitude
 * The average or standard lapse rate is 2 degrees Celsius per 1000 feet
 * Steep lapse rate is when the temperature decreases very rapidly with altitude, greater than 3 degrees per 1000 feet
 * Shallow lapse rate is when the temperature decreases very gradually, between 1.5 and 3.0 degrees Celsius per 1000 feet
 * Isothermal lapse rate is when there is no temperature change with altitude
 * Inversion is when the temperature increases with increasing altitude
 * Inversion is inverted lapse rate
 * Restricted to small layers of the atmosphere
 * Atmospheric pressure is the pressure exerted on a surface by the atmosphere due to the weight of a column of air directly above that surface
 * Always decreases with altitude
 * Decreases more rapidly at lower atmospheric levels due to the density decreasing as altitude increases
 * The standard units of pressure measurement are inches of mercury (in-Hg) and millibars (mb)
 * Inches of mercury is a measure of the height of a column of mercury that can be supported by atmospheric pressure
 * A millibar is a direct representation of pressure, which is defined as force per unit area
 * Sea level pressure is the pressure at mean sea level (MSL), measured directly at sea level or calculated if the station is not at sea level
 * Station pressure is the atmospheric pressure at an airfield or station
 * The standard atmosphere is the standard day at sea level conditions of 29.92 in-Hg at 15 degrees Celsius.
 * Isobars are lines of equal barometric pressure depicting the horizontal distribution on the earth’s surface
 * A high is an area of pressure where the center is at a higher pressure than the surrounding areas
 * A low is an area of pressure where the center is at a lower pressure than the surrounding areas
 * A ridge is an extension of the high pressure area
 * A trough is an extension of the low pressure area
 * Pressure gradient is the rate of pressure change in a direction perpendicular to the isobars (horizontal distance)
 * Gradient is steep when isobars are close together and shallow when they are far apart
 * Indicated altitude is the altitude read on an altimeter when the current local altimeter setting is displayed in the Kohlsmann window
 * Calibrated altitude is the indicated altitude corrected for instrument error
 * MSL altitude is the actual height above mean sea level (MSL)
 * AGL altitude is the aircraft’s height above the terrain directly below the aircraft and is measured in feet above ground
 * Pressure altitude is the height above the standard datum plane.
 * Standard datum plane is the actual elevation at which the barometric pressure is 29.92 in-Hg
 * Density altitude is the altitude in the standard atmosphere that had the same density as the local air
 * It is found by correcting the pressure altitude for non-standard temperature deviations
 * A change in pressure of 0.10 in-Hg will result in a change of 100 feet on the altimeter reading
 * If your flight path takes you into an area of higher MSL pressure the aircraft will be higher than the altimeter indicates
 * If your flight path takes you into an area of lower MSL pressure the aircraft will be lower than the altimeter indicates
 * For every 11 degrees Celsius that the temperature deviates from the standard, the altimeter will be in error by 4%
 * If the air is colder than the standard atmosphere, the aircraft will be lower than the altimeter indicates
 * If the air is warmer than the standard atmosphere, the aircraft will be higher than the altimeter indicates
 * All problems completed on legal pad

WINDS AND THEIR CIRCULATION
ELO 2.20 Identify the factors that affect wind circulation. ELO 2.21 Identify the forces that affect wind direction. ELO 2.22 Explain Coriolis force and its apparent effect on wind. ELO 2.23 In accordance with the Tri-Cellular theory describe the location of the semi-permanent high and low pressure centers. ELO 2.24 State the three major wind belts in the northern hemisphere that result from the Tri-Cellular theory. NORTHEAST TRADE WINDS PREVAILING WESTERLIES POLAR EASTERLIES ELO 2.25 Explain and identify gradient winds with respect to the isobars around high and low pressure systems in northern hemisphere. ELO 2.26 Explain and identify the surface wind direction with respect to the gradient winds in a high and low pressure system in the northern hemisphere. ELO 2.27 State the direction of the wind flow associated with high pressure and low pressure systems. ELO 2.28 Define Buys Ballot’s Law and describe its effect on an aircraft flying towards the center of a high or low pressure system. ELO 2.29 Describe the jet stream. ELO 2.30 Describe land and sea breezes. LAND BREEZE SEA BREEZE ELO 2.31 Describe valley and mountain winds. VALLEY WINDS MOUNTAIN WINDS
 * The irregular distribution of oceans and continents
 * The relative effectiveness of differing surfaces in transferring heat to the atmosphere
 * Irregular terrain
 * Daily variations in temperature
 * Changes of seasons
 * Other factors
 * The shape of isobars determines wind direction
 * Where a high pressure system displaces a low pressure system with small distances between them the air flow is direct
 * As distances between systems increase, other forces come into play:
 * Coriolis force
 * Friction
 * Gravity
 * Pressure gradient force
 * Coriolis force effects pockets of air migrating north or south and it causes the pocket to be pushed to the right regardless of which way it is headed
 * Northward winds get pushed ahead (to the right) as the rotation of the earth slows towards the north pole
 * Southward winds lag behind (to the right) as the rotation of the earth speeds towards the equator
 * Coriolis force is strongest at poles and decreases to zero at the equator
 * A low pressure area arises when the air over the equatorial region is heated, rises toward the tropopause, and results in an area of low pressure on the surface and extends from the equator to about 30 degrees north
 * An area of high pressure arises when the air beneath the subtropical jet stream subsides to the surface, and creates a high pressure belt at about 30 degrees north
 * Winds that travel from the northeast to southwest
 * Winds travel between the equator and 30 degrees north
 * Winds that flow from the west to the east
 * Winds travel between 30 degrees north and 60 degrees north
 * Winds that flow from the east to the west
 * Winds travel between 60 degrees north and the north pole
 * Gradient winds flow parallel to the isobars and above 2,000 feet AGL
 * Winds flow counter-clockwise around low pressure areas and are called cyclones
 * Winds flow clockwise around high pressure areas and are called anti-cyclones
 * Winds flow counter-clockwise around low pressure areas and are called cyclones
 * Winds flow clockwise around high pressure areas and are called anti-cyclones
 * Surface winds are deflected across isobars toward lower pressure
 * Winds flow counter-clockwise around low pressure areas and are called cyclones
 * Winds flow clockwise around high pressure areas and are called anti-cyclones
 * Buys Ballot’s Law states that if the wind is at your back, the area of lower pressure will be at your left
 * Aircraft tend to drift flying towards a high or low pressure system and if the pilot knows the change of pressure along the path he can estimate his direction of drift
 * The jet stream is a narrow band of strong winds found most often in the vicinity of the tropopause
 * Winds average 100-150 knots but can exceed 250 knots
 * Jet streams are three dimensional having a length, depth, and width
 * Meander in wavelike patterns around the globe and have profound effects on weather patterns
 * A land breeze is the movement of air from land to sea
 * Cooler air moves towards lower pressure over the water during the night
 * Shallow in depth
 * A sea breeze is the movement of air from sea to land
 * Do not penetrate far inland
 * Winds of up to 15-20 knots are not uncommon
 * Cool air over the water moves inland from the water during the day
 * Warm air moves up a mountain during the day, out of the valley
 * Cool air moves down the mountain at night, into the valley

CLOUDS AND MOISTURE
ELO 2.32 Define saturation, dew point, dew point depression, relative humidity, and specific humidity. SATURATION DEW POINT DEW POINT DEPRESSION RELATIVE HUMIDITY SPECIFIC HUMIDITY ELO 2.33 State the relationships between saturation, dew point temperature, and dew point depression that are necessary for the formation of clouds, fog, and precipitation. ELO 2.34 Explain the relationship between specific humidity and dew point temperature. ELO 2.35 Describe the three characteristics of precipitation. SHOWERS CONTINUOUS INTERMITTENT ELO 2.36 Describe the types of precipitation. DRIZZLE FREEZING DRIZZLE RAIN FREEZING RAIN HAIL ICE PELLETS SNOW GRAINS SNOW ELO 2.37 Describe how clouds form the flight conditions associated with cumulus, stratus, nimbostratus, altostratus, cumulonimbus, and cirrus. Clouds result in precipitation that affects flight conditions as follows: ELO 2.38 Describe the types of precipitation associated with the various clouds. CUMULUS CUMULONIMBUS STRATUS NIMBOSTRATUS ALTOSTRATUS CIRRUS
 * Saturation occurs when the actual specific humidity is equal to the maximum specific humidity and the air contains the maximum amount of water vapor
 * Dew point is the temperature at which moisture first starts to condense and form dew on exposed surfaces
 * Dew point depression is the difference, in degrees, between the air temperature and the dew point temperature
 * Percent of saturation
 * Ratio of water vapor weight to the weight of a total sample of air
 * The relationship exists in an equation stated as follows: RH = 100% - [2.5 x (T – TD)], where RH=relative humidity, T=temperature in degrees farenheight, and TD=dew point temperature in degrees farenheight
 * The relationship between specific humidity and dew point temperature is that the dew point is an indication of, and is directly related to specific humidity
 * Generally, the higher the specific humidity, the higher the dew point temperature and the more variable the weather
 * Characterized by a sudden beginning and ending and abruptly changing intensity and/or sky conditions
 * Associated with cumuliform clouds
 * Steady, intensity changes gradually, if at all
 * Associated with stratiform clouds
 * Stops and restarts at least once during the hour
 * May be showers or continuous
 * May be associated with cumuliform or stratiform clouds
 * Very small droplets of water which appear to float in the atmosphere
 * Drizzle which freezes on impact with objects
 * Precipitation in the form of water droplets which are larger than drizzle and fall to the ground
 * Rain which freezes on impact with objects
 * Small balls or other pieces of ice falling separately or frozen together in irregular lumps
 * Consists of alternate opaque and clear layers of ice in most cases
 * Transparent or translucent pellets of ice that are spherical or irregular
 * They usually bounce when hitting hard ground and make a noise on impact
 * Very small white, opaque grains of ice
 * Do not bounce or shatter upon impact
 * Usually fall is small quantities from stratus type clouds, never as showers
 * White or translucent ice crystals, usually of branched hexagonal or star-like form
 * Light Rain
 * Visibility is somewhat restricted
 * Forward visibility is restricted as rain picks up
 * Heavy Rain
 * Heavy rain on runways may cause hydroplaning
 * Loss of control may result
 * Visibility is severely reduced
 * Heavy rain ingested into the engines of a jet or turboprop aircraft in flight can cause power loss or actual power loss or even flameout
 * Snow
 * Can reduce vision and lead to a total lack of forward visibility
 * Buildup on the runway can cause enough friction to prevent the aircraft from reaching enough speed for takeoff
 * Hail
 * Can cause serious damage to the aircraft, but so can rain at high speeds
 * Dense, sharply outlined clouds, appearing singly or in groups throughout the sky
 * Light to moderate shower activity
 * Large, dense, towering clouds with cauliflower like top often flattened into an anvil shape or consists of a cirrus formation resulting from ice crystals
 * Thunderstorms, strong winds, precipitation is heavy, lightning
 * Well developed cumulonimbus may be the parent of the hailstorm and tornado
 * Form in layers with smooth bases and tops
 * Gray in appearance and cover the entire sky
 * Generally produces a light steady rain or drizzle
 * Dark massive cloud layers having a wet appearance
 * Accompanied by heavy precipitation of rain or snow
 * Only cloud that builds down in the atmosphere
 * Form a uniform blue or gray fibrous sheet covering all or most of the sky
 * Produce light to moderate precipitation
 * In some cases the sun may be barely visible
 * Composed of white, hair-like filaments, sometimes in an orderly pattern, that may cover all or part of the sky but do not obscure it
 * Composed of ice crystals and are transparent to sunlight
 * Contrails from high altitude aircraft are man-made cirrus clouds

ATMOPSPHERIC STABILITY
ELO 2.39 Describe atmospheric stability, instability, and neutral stability. ATMOSPHERIC STABILITY ATMOSPHERIC INSTABILITY NEUTRAL STABILITY ELO 2.40 Describe the adiabatic process. ELO 2.41 Describe the lapse rates, associated weather conditions, and the values of the dry and moist adiabatic lapse rates in degrees Celsius. ADIABATIC LAPSE RATE DRY ADIABATIC LAPSE RATE MOIST ADIABATIC LAPSE RATE ENVIRONMENTAL LAPSE RATE ELO 2.42 Describe the four types of lifting. CONVERGENCE FRONTAL OROGRAPHIC THERMAL ELO 2.43 Describe the conditions that must exist for conditional instability. ELO 2.44 Describe the conditions that must exist for convective instability. ELO 2.45 Identify the flight conditions associated with a stable and unstable atmosphere including cloud type, turbulence, precipitation, visibility, winds, and icing.
 * The atmosphere is said to be stable if it tends towards one single equilibrium point
 * The atmosphere is said to be unstable if it tends towards a point far from the equilibrium point
 * The atmosphere is said to be neutrally stable if it does not tend to move from its position either towards or away from the equilibrium point
 * The adiabatic process occurs when the temperature of a body of air changes without heat being added or taken away
 * Describes the temperature decrease that occurs when a quantity of air is lifted
 * As air descends it is compressed and warmed adiabatically
 * Decreases at a rate of 3 degrees Celsius per 1000 feet
 * Decreases at a rate of 1.5 degrees Celsius per 1000 feet
 * Moist air cools at a slower rate than dry air because heat is released during the condensation process as the air is lifted
 * Refers to the vertical temperature distribution within the atmosphere at any given time
 * Described as steep, shallow, isothermal, or as an inversion
 * Two winds converging at one point pushing the excess upward, consequently, areas of convergent winds are regions favorable to the occurrence of precipitation
 * A front flows in and pushes the air upward, displacing it
 * Wind pushes air upward by using a geographic feature such as a mountain, the air is pushed up the mountain into the sky
 * The sun creates heat that carries the air upward into the sky
 * Conditional instability exists when the environmental lapse rate falls between the moist and dry adiabatic lapse rates
 * Only factor determining stability is moisture
 * Convective instability exists when extensive lifting is applied to air which has a layer of extremely dry air overlying a layer of moist air
 * Lifting must be applied to a large volume of air
 * As the layers cool the top layer cools faster than the lower layer and this causes the more dense top layer to try to switch places with the lower layer resulting in a violent clash giving severe thunderstorms, tornadoes, and turbulent flight

AIR MASSES
ELO 2.46 Define and air mass. ELO 2.47 Describe the air mass classification system, including moisture content, temperature, and source region with respect to latitudes.
 * An air mass is a large body of air that has essentially uniform temperature and moisture conditions in a horizontal plane
 * May vary in size from several hundred to thousand miles
 * The air mass classification system is based on the location of the air masses source region and according to the surface (air or water) of their source region
 * Polar is not air from the poles, arctic is air from the poles

ELO 2.48 Describe the relationship between air mass temperature and stability. ELO 2.49 Identify the flight conditions associated with Maritime Polar, Continental Polar, Maritime Tropical, and Continental Tropical air masses.
 * If the air mass is warmer than the surface, it is cooled by contact with the cold ground, becomes more stable, and is called a warm air mass.
 * If the air mass is colder than the surface, it is heated from below, resulting in convective currents and instability, and is called a cold air mass
 * Maritime Polar
 * Consists of the open unfrozen polar sea areas
 * These areas are moist, but the moisture is sharply limited by the cold temperatures
 * Considerable precipitation results in these areas
 * Turbulence is considerable along mountain ranges due to the instability of the air and high velocities associated with movements over irregular terrain
 * Icing conditions over mountains may also be severe
 * After crossing the mountains the air begins to descend and warm adiabatically and the Maritime Polar Mass is reclassified as a Continental Polar Mass
 * Continental Polar
 * Consists of land areas dominated by the Canadian and Siberian high pressure cells
 * Air is very dry
 * Stability decreases as the air warms causing the lapse rate to become steeper
 * Turbulence and snow flurries will form over rough terrain
 * Air flowing over warm water experiences rapid heating resulting in rapid instability resulting in fog
 * As air approaches mountains it is subject to orographic lifting causing instability resulting in cumulus clouds that may develop into cumulonimbus
 * Maritime Tropical
 * Air is warm and can hold considerable moisture
 * Due to the moisture level, condensation may result in fog, low stratus, steady precipitation, or any combination of these
 * As air approaches mountains, the conditional instability will be released resulting in possible thunderstorms or at least large and troublesome cumuliform clouds
 * As air approaches flat land, the lift is not sufficient to release the instability and fog, or low stratus, will form, especially in the morning hours and may last for many hours covering thousands of square miles
 * In the summer air moving north undergoes strong thermal heating resulting in towering cumulus and cumulonimbus clouds that give scattered rain storms and thunderstorms which should be avoided but usually die out by the evening
 * Continental Tropical
 * Consists of very warm and dry air, often called superior
 * Due to low humidity cloud cover is sparse, yet when present they are of the cumuliform type and found mainly over mountains
 * Flying is usually rough during the middle and low levels, especially during the day when surface heating increases instability

FRONTAL SYSTEMS
ELO 2.50 Define the terms front and frontogenesis. FRONT FRONTOGENESIS ELO 2.51 Define the general characteristics of a front, including its structure. ELO 2.52 Describe the polar front. ELO 2.53 Describe the continuities used to locate and classify fronts. ELO 2.54 Describe the factors that influence frontal weather. ELO 2.55 Describe the conditions associated with cold fronts. ELO 2.56 Describe the characteristics of the squall line. ELO 2.57 Describe the conditions associated with a warm front. ELO 2.58 Describe the conditions associated with a stationary front. ELO 2.59 Describe the conditions associated with occluded fronts. ELO 2.60 Describe the conditions for upper fronts to develop. ELO 2.61 Describe the conditions associated with an inactive front.
 * A front is an area of discontinuity that forms between two contrasting air masses when they come together
 * These air masses must have sufficiently different temperature and moisture properties
 * Frontogenesis means the formation of a new front or the regeneration of a decaying front
 * Temperature and pressure change
 * Winds usually shift 90 degrees from one side to another
 * Ahead of the front the, the wind blows parallel to the front and toward the lower pressure
 * Behind the front, the wind blows perpendicular to the front and pushes the front along
 * The speed of movement is often different
 * Frontal cloud and precipitation patters of most fronts are not recognizable above 15,000 to 20,000 feet
 * The most significant frontal weather occurs in the lower layers of the atmospheres
 * Temperature contrast between the air masses can extend up to the tropopause
 * The polar front is the zone separating the warm tropical air masses and the cold polar air masses in the middle latitudes
 * The polar front is not stationary
 * Differences in the various properties of adjacent air masses, such as temperature, moisture (indicated by the dew point), wind, and pressure are used to locate and classify fronts
 * A front’s slope is determined largely by surface friction acting on an air mass below 2,000 feet and by the varying velocities of the air masses involved
 * Shallow frontal slopes produce extensive cloudiness
 * Steep frontal slopes produce narrow bands of cloudiness
 * The speed of a frontal movement affects the weather associated with it
 * Faster moving fronts are accompanied by poor weather
 * Slower moving fronts have less severe weather
 * The degree of stability of the air s lifted determines whether the cloudiness will be predominantly stratiform or cumuliform
 * Stratiform gives mostly steady precipitation and little or no turbulence
 * Cumuliform gives showers and turbulence
 * Moisture is necessary for the formation of clouds and weather hazards
 * With no water vapor present in the air, flight conditions would be perfect and there would be no worries about weather or clouds
 * The upward motion often produces violent unstable conditions including cumulonimbus clouds, strong thunderstorms, and severe turbulence
 * Rain showers or snow showers are present
 * Barometric pressure decreases
 * Cold frontal slopes range from 1/50 to 1/150 and average about 1/80
 * A squall is a nonfrontal line of violent thunderstorms, or cumulonimbus clouds
 * Most occur in the warm air mass
 * Develop 50 to 300 miles in ahead of the front and parallel to it
 * Contain severe weather conditions including turbulence, hail, icing, lightning, heavy rain, and/or tornadoes
 * Slower moving than a cold front
 * Not as defined as cold fronts
 * Warm frontal slopes range between 1/50 and 1/200 with an average of 1/100
 * Showery precipitation accompanies warm fronts
 * Neither air mass replaces the other
 * Surface winds tend to blow parallel on both sides of the front rather than against and/or away from it
 * Similar weather as warm fronts, just less intense
 * May persist in one area for days
 * Form when a warm and cold front meet
 * Three air masses are present
 * Cold (most dense) air mass
 * Cool (less dense) air mass
 * Warm (least dense) air mass
 * Warm is located in between the other two
 * Forms when the cold front gradually overtakes the warm front
 * Type of occlusion depends on which front is in contact with the ground
 * Generally align themselves in a north south direction
 * Exhibits weather characteristics from both warm and cold fronts
 * Will move northeast at the speed of the front maintaining contact with the ground
 * Cold front occlusion
 * Cold front remains in contact with the ground
 * Occurs when the air mass behind the cold front is colder and more dense than the cool air mass in advance of the warm front
 * Situation resembles a typical cold front
 * Warm front occlusion
 * Warm front remains in contact with the ground
 * Occurs when the air mass ahead of the warm front is colder and more dense than both the cold air mass behind the cold front and the warm air mass
 * Situation resembles a typical warm front
 * Occurs primarily in the winter
 * Cold front moves over an even colder air mass lying in the lower layers of the atmosphere
 * Clouds and precipitation do not accompany inactive fronts
 * Warm air mass may be too dry for clouds to form even after the air mass has lifted
 * Often referred to as dry fronts

THUNDERSTORMS
ELO 2.62 Describe the requirements for thunderstorm formation. ELO 2.63 Describe the thunderstorm life cycle and the characteristics of each stage, including pressure variations. ELO 2.64 Describe the two types of thunderstorms. FRONTAL THUNDERSTORMS ELO 2.65 Identify the hazards associated with thunderstorms. ELO 2.66 Define microburst. ELO 2.67 Identify the characteristics of a microburst ELO 2.68 Describe the formations and conditions associated with tornado activity. ELO 2.69 Explain how radar can aid a pilot when flying in the vicinity of thunderstorms. ELO 2.70 Describe the recommended techniques for flight in or near thunderstorms.
 * The requirements for thunderstorm (cumulonimbus cloud) formation are as follows:
 * Lifting Action
 * Necessary to bring warm air near a point where it will rise continuously
 * Normally provided by orographic effects, fronts, thermals, or convergence
 * Unstable Air
 * Created when lifted air becomes high enough that it is warmer than the surrounding air (e.g. steep lapse rate)
 * Also provided by convective instability
 * Moisture
 * Formed when air is lifted to the point where water vapor condenses
 * Dew point temperatures of 80 degrees or higher are excellent indicators of thunderstorms activity
 * Building Through The Freezing Level
 * Causes cloud droplets to freeze
 * Collisions cause a separation of charge released in the form of lightning
 * Thunderstorms progress through three stages during their life cycle; the cumulus stage, the mature stage, and the dissipating stage
 * Cumulus Stage
 * Initial stage of a thunderstorm is always a cumulus cloud
 * Main feature of this stage is the updraft which may extend from near the earth’s surface to several thousand feet above the visible cloud top
 * Strongest updrafts occur at higher altitudes late in the stage and they may be greater than 3,000 feet per minute
 * Stage has no precipitation due to moisture being carried upward in the updrafts but severe turbulence exists
 * As the cloud forms, water vapor changes to liquid and/or ice particles providing a source of energy for the developing cloud
 * Mature Stage
 * Reached when rain and ice become too heavy to be supported by the cloud and begin to fall
 * Average cell grows to a height of 25,000 feet during this stage
 * Updrafts continue to increase in speed and may exceed up to 6,000 feet per minute
 * Cold air accelerates creating downdrafts that may reach a velocity of up to 2,500 feet per minute
 * Produces a sharp temperature drop, and strong, gusty surface winds
 * Leading edge of this is called the gust front
 * Updrafts and downdrafts result in wind shear that produces severe turbulence
 * Thunderstorms reach their most intense time in this stage and are located in the upper 2/3 of the cell
 * Dissipating Stage
 * Downdrafts continue to develop while updrafts continue to weaken
 * Eventually the entire thunderstorm becomes an area of downdrafts with precipitation in the dissipating stage
 * The thunderstorm dissipates when there are no updrafts present
 * Storms can dissipate without the entire loss of updrafts
 * Pressure Changes
 * A rapid fall in pressure as the storm approaches
 * An abrupt rise in pressure with the onset of the first gust and arrival of rain showers
 * A gradual return to normal pressure as the storm passes and the rain ceases
 * Caused by the lifting of warm, moist, unstable air over a frontal surface
 * Normally form in lines
 * Warm-frontal thunderstorms
 * Least intense
 * Not a strong lifting action
 * Cold-frontal thunderstorms
 * Most intense
 * Form in a continuous line and typically in the afternoon
 * Stationary-frontal thunderstorms
 * Normally widely scattered
 * Occluded-frontal thunderstorms
 * Dangerous because they can be embedded in stratiform clouds and therefore difficult to see
 * The hazards associated with thunderstorms are extreme turbulence, hail, microburst, icing, lightning, and tornadoes
 * A microburst is an intense highly localized downward atmospheric flow with velocities of 2,000 to over 6,000 feet per minute
 * May emanate from any convective cloud
 * Dangerous during takeoff, approach, and go-around phases of flight
 * May develop in families of two or more
 * Visual indicators include virga, localized dust blowing, rain shafts with rain diverging away from the core of the cell, roll clouds, and an indication of vivid lightning or tornado-like activity
 * Likely with gusty winds, heavy rain, or thunderstorms
 * Form out of the top of a cumulonimbus cloud
 * Winds range from 10-300 mph
 * Land speed is 25-40 mph
 * High winds are the primary destructive force
 * Flying debris is the second force
 * Third force is falling buildings
 * The fourth is the explosive force associated with the rapid drop in outside pressure in relation to the higher pressure inside of buildings and houses
 * Requirements for formation are:
 * Warm and moist air near the earth’s surface
 * Cold and dry air in the middle atmosphere
 * Strong upper level winds
 * Presence of cumulonimbus clouds
 * Conditions indicating tornado activity
 * Pronounced horizontal wind shear
 * Rapidly moving cold front or squall
 * Strong convergence
 * Marked convective instability
 * Dry air mass superimposed on a moist air mass, abrupt change in moisture content, usually below 10,000 feet
 * Marked convection to the –10 degrees Celsius isotherm
 * Let pilot know where thunderstorm is as it usually contains turbulence
 * Pilot can circumnavigate the storms
 * Most helpful when there are several thunderstorms present which are obscured by multiple cloud layers
 * Airborne weather radar should be used as an avoidance rather than a penetration tool
 * If at all possible avoid thunderstorms
 * Do not venture closer than 20 miles to any mature visible storm cloud with overhanging anvils because of the possibility of encountering hail
 * Do not attempt to fly under orographic thunderstorms even if the area on the other side of the mountain can be seen
 * Avoid flying under thunderstorms because updrafts and downdrafts can exceed the performance of the aircraft
 * If circumnavigation is impossible, the next best thing is to fly over the top

TURBULENCE
ELO 2.71 List the intensities used to describe turbulence. ELO 2.72 Define the terms used to report turbulence with respect to time. ELO 2.73 Describe how thermal turbulence develops. ELO 2.74 Describe the cloud formations associated with thermal turbulence ELO 2.75 Describe how mechanical turbulence develops. ELO 2.76 Describe the cloud formations and conditions associated with mountain wave turbulence. ELO 2.77 Describe the rules for flight in the vicinity of mountain waves. ELO 2.78 Describe how frontal lifting creates turbulence. ELO 2.79 Describe how large scale wind shear creates turbulence. ELO 2.80 Describe the flight techniques for turbulence avoidance.
 * The intensities used to describe turbulence are light, moderate, severe, and extreme
 * Occasional Less than 1/3 of the time
 * Intermittent 1/3 to 2/3 of the time
 * Continuous More than 2/3 of the time
 * Thermal turbulence occurs when cold air moves over warmer ground and is heated, or by localized convective currents due to surface heating
 * Cumulus clouds form when the air is moist and are convective-type clouds
 * Mechanical turbulence occurs from wind flowing over or around irregular terrain or other obstructions
 * Lenticular Clouds
 * Smooth in contour but may be quite ragged
 * May occur singularly or in layers at heights usually above 20,000 feet
 * Stationary in position
 * Rotor Clouds
 * Forms at a lower level and is generally found at about the same height as the mountain ridge
 * Cap Cloud
 * Usually obscures both sides of the mountain peak
 * Must be avoided due to turbulence and obscuring the mountain peak
 * Turbulence
 * Severe turbulence can frequently be found from the surface to the tropopause and 150 miles downwind when the winds are greater than 50 knots at the mountaintop
 * Extreme turbulence can often be found at low levels on the leeward side of the mountain in or near the rotor and cap clouds when the winds are 50 knots or greater at the mountaintop
 * Moderate turbulence often can be experienced out to 300 miles under the previously stated conditions
 * The following rules should be applied when mountain wave turbulence has been forecast:
 * 1) Avoid turbulence if possible by flying around the areas, if it is impossible to avoid fly at a level that is at least 50% higher than the height of the nearest mountain range along your flight path
 * 2) Avoid the rotor, lenticular, and the cap clouds since they contain intense turbulence and strong updrafts and downdrafts
 * 3) Approach the mountain range at a 45 degree angle so that a quick turn can be made to avoid the ridge in the event of a downdraft
 * 4) Do not place too much confidence in your pressure altimeter reading near mountain peaks, they may include altitudes that are more than 2,500 feet higher than your true altitude
 * 5) Penetrate turbulent areas at air speeds recommended for your aircraft
 * The lifting of warm air by a frontal surface leading to the instability and/or wind shear between the warm and cold air masses causes frontal turbulence
 * The most severe cases of frontal turbulence are generally associated with fast moving cold fronts
 * Frequently found around jet streams where large shears in both the horizontal and vertical planes are found as well as in association with land and sea breezes, fronts, inversions and thunderstorms
 * A narrow zone of wind shear, with its accompanying turbulence, will sometimes be encountered in flight by aircrews as they climb or descent through a temperature inversion
 * Always avoid turbulence whenever possible and avoid areas of changing winds and wind shear
 * If it cannot be avoided follow the following techniques for turbulence avoidance:
 * Trim the aircraft for level flight at the recommended turbulence air penetration airspeed
 * Severe turbulence may cause changes in indicated airspeed, do not chase airspeed
 * The key to flying through turbulence is proper attitude control, both pitch and bank should be controlled by reference to attitude indicator
 * Establish and maintain thrust settings consistent with turbulent air penetration airspeed and aircraft attitude
 * Severe vertical gusts may cause appreciable altitude deviations, allow altitude to vary
 * Sacrifice altitude to maintain desired attitude, do not chase altimeter

ICING
ELO 2.81 Identify the effects and hazards of aircraft icing. ELO 2.82 Describe supercooled water. ELO 2.83 Describe wet snow and avoidance techniques. ELO 2.84 State the requirements for the formation of structural freezing. ELO 2.85 State the temperature range most conducive to structural icing. ELO 2.86 Describe the factors affecting the accumulation of structural icing. ELO 2.87 Describe the different types of anti-icing and deicing equipment. DEICING EQUIPMENT ANTI-ICING EQUIPMENT ELO 2.88 Describe the types of structural icing. CLEAR ICE RIME ICE MIXED ICE FROST ELO 2.88A Describe the hazards of structural icing. ELO 2.89 Describe induction icing, compressor icing, and fuel systems icing. INDUCTION ICING COMPRESSOR ICING FUEL SYSTEMS ICING ELO 2.90 Describe the ground icing hazards. ELO 2.91 Identify icing conditions associated with air masses, fronts and thunderstorms. AIR MASS ICING FRONTAL ICING THUNDERSTORM ICING ELO 2.92 Identify the procedures to minimize or avoid effects of icing. ELO 2.93 Identify the types and intensity of icing. TYPES - Rime Ice - Mixed Ice INTENSITIES ELO 2.94 Describe the importance of Pilot Reports (PIREPS).
 * The presence of ice on an aircraft increases weight and drag and decreases lift and thrust, thereby decreasing performance
 * Icing disrupts the smooth flow of air over airfoils, thereby decreasing lift and thrust, increasing drag, and increasing stall speed
 * Icing can cause vibration that can cause damage to the aircraft
 * Engines, fuel, and other instruments can also malfunction due to icing
 * Supercool water is liquid found at air temperatures below freezing
 * Supercool water droplets are numerous in clouds at temperatures between 0 and –15 degrees Celsius
 * As supercooled water strikes a wing it forms ice resulting in icing
 * Wet snow in its true state forms as the result of deposition in the upper limits of clouds
 * Occurs at temperatures just below freezing
 * The pilot can climb to increasing altitudes where moisture is not present and snow flakes will not cause flaking or he can drop to altitudes well above freezing if terrain and lapse rate permit
 * The three requirements for structural freezing are outside air temperature below freezing, aircraft skin temperature below freezing, and visible moisture
 * The most severe icing is encountered between 0 and –10 degrees Celsius
 * Dangerous conditions can be encountered below –10 degrees Celsius
 * The rate of ice accumulation on an aircraft is affected by the following items:
 * The size and number of water drops in a given volume of air
 * Small drops follow the airflow, large drops resist the airflow and strike the airfoil more readily than small drops
 * Airfoil thickness
 * Thick airfoils have a larger deflective force so they collect ice more slowly than thinner air foils which have a smaller deflective force
 * Airspeed
 * As airspeed is increased more water is encountered and thus buildup is increased
 * Eliminates or removes ice that has already accumulated on the aircraft
 * Rubber boots on leading edges of lift producing surfaces inflate and deflate to crack ice and allow the air stream to peal it off
 * Heat, fluid, and mechanical techniques are also used to de-ice
 * Anti-icing fluids are freezing point depressants and are pumped through small holes in the wing’s leading edge
 * Critical areas can be heated electrically in newer aircraft
 * Clear ice forms at temperatures between 0 and –10 degrees Celsius, but my occur at up to –25 degrees Celsius
 * Occurs in cumuliform clouds with appropriate temperatures where vertical currents can large drops
 * Rime ice is a milky white, opaque and granular deposit of ice formed through the rapid freezing of small supercooled water droplets
 * Most likely to occur at temperatures from –10 to –20 degrees Celsius
 * Rime ice can be expected in stratiform clouds since vertical currents are not strong enough to support large droplets
 * Mixed ice is a combination of clear ice and rime ice
 * Most frequent type encountered
 * Frost is a thin layer of crystalline ice that forms on exposed surfaces when the temperature of the exposed surface is below freezing and the dew point of the air is below freezing
 * Also occur when both the temperature and the dew point are below freezing and they are within 5 degrees of each other, the night skies are clear, and the winds are calm
 * May form when the free air temperature is slightly above freezing
 * The most hazardous aspect of structural icing is its aerodynamic effects
 * Ice can alter the shape of an airfoil
 * Ice thickness, along with location, roughness, and shape all determine the effect of icing
 * Roll upset is an uncommanded and uncontrolled roll phenomenon resulting from airflow separation that causes self deflection of the ailerons
 * A tailplane (empennage) stall occurs when, as with the wing, the critical angle of attack is exceeded
 * Application of flaps can aggravate or initiate the stall in two situations, when the flaps are approaching the fully extended position or during flight through wind gusts
 * Occurs at the air intake duct
 * Similar to wing icing when below freezing
 * When above freezing, induction icing can occur when the reduced pressure that exists at the intake lowers the temperature to the point that condensation and/or deposition take place, resulting in the formation of ice
 * Occurs on compressor inlet screens and compressor inlet guide vanes
 * Restricts the flow of inlet air
 * Causes thrust and a rapid rise in exhaust gas temperature
 * Ice build-up on inlet screens sufficient enough to cause turbine failure can occur in less than one minute in severe conditions
 * As an aircraft is refueled in the rain or in high humidity, the fuel absorbs water and can cause frozen fuel lines under cold outside air conditions
 * Results in an engine flameout
 * Water or slush that is blown onto the aircraft can form an ice cover on the under side of flaps, control surfaces, and the landing gear mechanism
 * Ice and snow on runways can cause problems breaking
 * Stable air masses often produce stratus-type clouds with extensive areas of rime icing conditions
 * Unstable air masses generally produce cumulous clouds with limited horizontal extent of icing conditions
 * Pilots can tend to expect more icing while flying over mountainous terrain under icing conditions, than over other types of terrain with the same atmospheric conditions
 * Cold fronts and squall lines generally have a narrow weather and icing band
 * Associated clouds will be cumuliform
 * Icing will be predominantly clear
 * Warm fronts and stationary fronts generally have a wide weather and icing band with stratiform clouds
 * Icing will be predominantly rime
 * Rain or drizzle falling from warm air above to cold air below causes severe clear icing and evasive action is to climb to an altitude where the temperature is above freezing
 * Occluded fronts often produce a wide weather and icing band with both stratiform and cumuliform-type clouds
 * Icing will be clear, mixed, and rime
 * Worst conditions encountered at or above the freezing level
 * Cumulus cloud
 * Icing is clear from 0 to –5 degrees Celsius
 * Icing is mixed from –5 to –10 degrees Celsius
 * Icing is rime from –10 degrees Celsius and below
 * Mature cloud
 * Icing temperatures same as for cumulus cloud
 * No icing in downdrafts, only in updrafts
 * Dissipating
 * Icing is clear and mixed from 0 to –5 degrees Celsius
 * No icing below –5 degrees Celsius due to downdrafts
 * Do not fly parallel to a front while encountering icing conditions
 * Avoid the area below 4,000 or 5,000 feet above ridges when flying on instruments through clouds at indicated air temperatures less than 0 degrees Celsius
 * Do not make steep turns with ice on the airplane due to increased stall speeds
 * Do not land with reduced power, use higher airspeeds when the potential for ice on the wings or other exposed surfaces exists
 * Avoid high angles of attack when ice has formed on the aircraft since stalling speeds are increased
 * Do not forget when flying under icing conditions, that fuel consumption is greater, due to increased drag and the additional power required
 * Avoid icing conditions as much as possible in the terminal phase of flight due to reduced airspeeds
 * Always remove ice or frost from airfoils before attempting to take off
 * In stratiform clouds, you can likely alleviate icing by changing to a flight level with above-freezing temperatures or to one colder than –10 degrees Celsius; an altitude change may also take you out of the clouds
 * Clear Ice
 * Clear ice forms at temperatures between 0 and –10 degrees Celsius, but my occur at up to –25 degrees Celsius
 * Occurs in cumuliform clouds with appropriate temperatures where vertical currents can large drops
 * Rime ice is a milky white, opaque and granular deposit of ice formed through the rapid freezing of small supercooled water droplets
 * Most likely to occur at temperatures from –10 to –20 degrees Celsius
 * Rime ice can be expected in stratiform clouds since vertical currents are not strong enough to support large droplets
 * Mixed ice is a combination of clear ice and rime ice
 * Most frequent type encountered
 * Trace
 * Ice becomes perceptible
 * Rate of accumulation slightly greater than that of sublimation
 * Not hazardous
 * Light
 * Over one hour in this environment can create a problem
 * Occasional use of anti-icing/deicing equipment needed to maintain no hazards
 * Moderate
 * Rate of accumulation is such that even short encounters are dangerous
 * Use of anti-icing/deicing equipment is necessary
 * Heavy
 * Rate of accumulation is such that anti-icing/deicing equipment fails to reduce or control the hazard
 * Immediate diversion is necessary
 * PIREPS are the only form of knowledge the pilots have in regards to the icing conditions ahead.
 * Accurate reports from other pilots can be vital to the safety of another aircraft

CEILINGS AND VISIBILITY
ELO 2.95 Define the following terms: visibility, flight visibility, prevailing visibility, slant range visibility, and runway visual range. VISIBILITY FLIGHT VISIBILITY PREVAILING VISIBILITY SLANT RANGE VISIBILITY RUNWAY VISUAL RANGE ELO 2.96 Identify the amount of sky coverage associated with the following terms: sky clear, few, scattered, broken, overcast, and vertical visibility. CLASSIFICATION	MEANING	SKY COVERAGE SKC	Sky Clear	0/8 ths FEW	Trace	0/8 – 2/8 ths SCT	Scattered	3/8 – 4/8 ths BKN	Broken	5/8 – 7/8 ths OVC	Overcast	8/8 ths VV	Vertical Visibility	8/8 ths ELO 2.97 Define and identify obscuring phenomena. ELO 2.98 Define ceiling and vertical visibility. CEILING VERTICAL VISIBILITY ELO 2.99 Describe how the vertical visibility and obscuring phenomena may constitute a ceiling. ELO 2.100 Define fog. ELO 2.101 Identify the four requirements for fog formation. ELO 2.102 Describe how winds aid in the formation and dissipation of fog. ELO 2.103 Identify the specific types of fog. ELO 2.104 Identify how specific types of fog form and dissipate. RADIATION FOG ADVECTION FOG UPSLOPE FOG STEAM FOG ICE FOG
 * Visibility is the ability to see and identify prominent unlighted objects by day and prominent lighted objects by night, and is expressed in statute miles, hundreds of feet, or meters
 * Flight visibility is the average forward horizontal distance, measured in statute miles from the cockpit of an aircraft in flight, at which prominent unlighted objects may be seen and identified by day and prominent lighted objects may be seen and identified by night
 * Prevailing visibility is the greatest horizontal visibility, measured in statute miles, equaled or exceeded throughout at least half the horizon circle, which need to be continuous
 * Slant visibility is the distance on final approach when you can see the runway
 * Runway visual range is the horizontal distance, expressed in hundreds of feet or meters, a pilot will see by looking down the runway from the approach end
 * Obscuring phenomena are any collection of particles, such as haze, fog, smoke, volcanic ash and blowing spray to name a few which reduce horizontal visibility to less than seven miles
 * They may be either surface based or aloft
 * A ceiling is the height above the ground (AGL) ascribed to the lowest broken or overcast layer; or the vertical visibility into an obscuring phenomena
 * Vertical visibility is the distance that can be seen directly upward into an obscuring phenomena
 * If the celestial dome is totally hidden from view (8/8’s) by some upward as seen from the ground
 * The obscuring phenomenon reduces the slant range visibility in the case of vertical visibility
 * Due to this, the pilot will have difficulty seeing the runway or approach lights clearly even after descending below the level of the reported vertical stability
 * Fog is a visible aggregate of minute water particles (droplets) which are based at or within 50 feet of the surface, greater than 20 feet in depth, and reduces the prevailing visibility to less than 5/8 of a statute mile
 * Reduces horizontal and vertical visibility and may extend over a large area
 * The four conditions are as follows:
 * The air must have a high water content
 * The temperature and dew point temperature must be equal (or nearly so)
 * Condensation nuclei must be present in the air
 * Light surface winds must be present, calm winds (zero knots) will not produce fog
 * Winds of 1 to 5 knots will produce eddy currents and a layer of fog with bases between 2 and 10 feet
 * Winds of 5 to 10 knots will produce eddy currents and a layer of fog with bases up to 50 feet
 * Higher wind speeds normally will cause the fog to lift and become a stratus type cloud or dissipate altogether
 * Fogs are classified as either air mass or frontal and the specific types of fog are: radiation, advection, upslope, and frontal, steam and ice
 * Radiation fog occurs because of a reduction in air temperature as a result of nocturnal cooling
 * Nocturnal cooling of air is defined as the night-time radiational cooling that occurs over land areas
 * An increase in the surface air temperature increases the ability of the air to hold more water vapor, and the fog particles tendevaporate
 * Advection fog occurs when warm, moist air moves over a cold surface and the air cools to below its dew point
 * Common in coastal areas, often referred to as sea fog
 * Dissipation is caused by a "wind shift"
 * Upslope fog forms when orographic lifting causes enough adiabatic cooling to reduce the air temperature to the dew point temperature
 * Dissipation generally occurs when a wind shift pushes the air down the slope and causes adiabatic warming
 * Steam fog is an evaporation fog forming when cold air moves over warmer water
 * Occurs frequently in the winter over open bodies of water in polar regions
 * Steam fog rises from the surface like smoke
 * Steam fog dissipates by heating the air through conduction
 * Ice fog is a form of radiation fog that forms in moist air during extremely cold, calm conditions
 * Occurs mostly in the arctic

=WEATHER=

General Structure of the Atmosphere
2.1 Characteristics of the troposphere, tropopause, and stratosphere & 2.2 The flight characteristics associated with the troposphere, tropopause, and stratosphere. Troposphere: the layer adjacent to the earth’s surface; varying in height from 55,000’ at the equator to 28,000’ at the polls. Atmosphere becomes less dense with altitude and roughly 50% of it, by weight lies below 18,000’ and 90% below 53,000’. Tropopause: the transition zone between the troposphere and stratosphere Stratosphere: has increasing temperature with altitude due to the ozone layer which plays a major part in heating the air 2.3 Identify the six weather elements that a pilot may encounter Memorize as TAW PRECH 2.4 Identify the six primary hazards of flight
 * The temperature decreases with altitude.
 * An abrupt change in the lapse rate signals the start of the tropopause.
 * Large amounts of moisture and condensation nuclei are found.
 * Most weather systems are within this boundary
 * Temperature is constant with altitude.
 * Winds normally increase in speed with altitude below the tropopause.
 * Contrails form and persist since it is normally the coldest areas within the lower atmosphere at –57° C
 * Water vapor and large scale vertical currents do no exist to any extent
 * Flying in the stratosphere is generally smooth with excellent visibility.
 * The air is thin and offers very little resistance to flight.
 * Above these are the Mesosphere and the Thermosphere
 * Temperature
 * Atmospheric Pressure
 * Wind
 * Humidity
 * Clouds
 * Precipitation
 * Turbulence
 * Thunderstorms
 * Wind Shear
 * Icing
 * Low Ceilings
 * Low Visibility

Atmospheric Temperature and Pressure
2.5 Define specific heat and how it effects the warming of the earth 2.6 State the primary source for all weather 2.7 Define Lapse Rate and 2.8 State the average lapse rate in degrees Celsius 2.9 List and define lapse rates: steep, shallow, isothermal, and inversion relative to the standard lapse rate 2.10 Define atmospheric pressure 2.11 State the standard units of pressure measurement 2.12 Differentiate between sea level pressure and station pressure 2.13 Define the Standard Atmosphere to include temperature and pressure 2.14 List the major items found on the surface pressure/analysis chart 2.15 Explain Pressure Gradient 2.16 Define Indicated Altitude, Calibrated Altitude, Mean Sea Level, Altitude, Above Level Ground Altitude, Pressure Altitude, Density Altitude 2.17 Describe the effects of pressure changes on aircraft altimeters 2.18 State the effects temperature deviations from the standard lapse rate on aircraft altimeters 2.19 Calculate MSL altitude, AGL altitude, and the altimeter error resulting from a change in atmospheric pressure IF you fly at 5000’ from a station that is 500’ and 30.2 in-HG to a station that is 800’ and 30.0 in-HG… do the following 2.20 Identify the factors in Wind Circulation The recurring movement of air relative tot he earth’s surface. It is created primarily by the large temperature difference between the tropics and the polar regions, and complicated by uneven heating of the land and water areas by the sun. The circulation is caused by: 2.21 Identify the forces affecting wind direction 2.22 Explain Coriolis Force and its apparent effect on wind 2.23 In accordance to the Tri-Cellular Theory describe the location of the semi-permanent high and low pressure centers 2.24 State the three major wind belts in the northern hemispher that result from the Tri-Cellular Theory Read 2.3-9 2.25 Explain and identify gradient winds with respect to the isobars around high and low pressure systems in the Northern Hemisphere See figure 2.3-6 2.26 Explain and identify the surface wind direction with respect to the gradient winds in a high and low pressure system in the Northern Hemisphere 2.27 State the direction of the wind flow associated with high pressure and low pressure systems 2.28 Define Buys Ballot’s Law and describe its effect on an aircraft flying towards the center of a high or low pressure system 2.29 Describe a Jet Stream 2.30 Describe Land and Sea Breezes 2.31 Describe Valley and Mountain Winds
 * Is the amount of heat required to raise the temperature of one gram of a substance one degree Celsius. The specific heat of a substance is constant and can be thought of as its heat capacity.
 * During the day a land surface will heat faster and to a much greater extent than will a water surface. It will also cool at night much faster and to a greater extent than water. The specific heat of water is about four times that of most land surfaces
 * The sun heats the earth during the day. Insolation is the total radiation reaching the earth’s surface and it is the primary source for all weather phenomena on earth.
 * Lapse rate is the change in atmospheric temperature with the increasing altitude. It is 2° C / 1000’
 * STEEP 3° C / 1000’
 * SHALLOW 1.5-3° C/1000’
 * ISOTHERMAL no change with altitude
 * INVERSION temperature increases with altitude
 * The pressure exerted on a surface by the atmosphere due to the weight of a column of air directly above that surface. It always decreases with altitude. The higher you are the faster it decreases.
 * Inches of Mercury and millibars. It varies from 28 in-HG to 31 in-HG.
 * In the lower altitude, 1000’ increases in altitude will result in a pressure decrease of 1 in-HG (34 mb)
 * SLP is the pressure at mean seal level (MSL) measured directly at sea level or calculated if the station is not at sea level
 * Station Pressure is the atmospheric pressure at the airfield or station
 * MSL is used as a reference level for all surface pressure observations
 * 29.92 in-HG at 59° F
 * 1013.2 mb at 15° C
 * Isobars – lines of equal barometric pressure
 * Highs- where the pressure in the center is higher than surrounding areas
 * Lows – where the pressure in the center is lower than surrounding areas
 * Ridge – is an extension of high pressure area
 * Trough – is an extension of low pressure area
 * The rate of pressure change in a direction perpendicular to the isobars and can be steep (strong) or shallow (weak) depending on the distance the isobars are apart. It is the initiating force for all winds!
 * Indicated Altitude – the altitude read on the altimeter when the current local altimeter setting is displayed in the Kohlsman window
 * Calibrated Altitude – the indicated altitude corrected for instrumental error
 * Mean Sea Level, Altitude – the actual distance above mean sea level and is found by correcting calibrated altitude for temperature deviations from the standard atmosphere
 * Above Level Ground Altitude – the aircraft’s height above the terrain directly beneath the aircraft and is measured in feat above ground level
 * Pressure Altitude – the height above the standard datum plane where barometric pressure is 29.92 in-Hg
 * Density Altitude – the altitude in the standard atmosphere that has the same density as the local air. It is found by correcting the pressure altitude for non standard temperature deviations (gives an idea of engines performance)
 * A change of .1 in-Hg will change the altimeter reading by 100’
 * If going from H to L, the aircraft will be lower than altimeter indicates.
 * If going from L to H, the aircraft will be higher than altimeter indicates.
 * If the air is colder than standard atmosphere (H to L temps), the aircraft will be lower than altimeter indicates, and if the air is warmer than standard (L to H), the aircraft will be higher than the altimeter reading. For every 11° C that the temperature varies, the altimeter will be in error by about 4%.
 * Moving from high to low pressure so look out below!
 * 30.2 – 30.0 = .2 in-Hg
 * .2 * (1" = 1000’) = 200’
 * Actual MSL will be 5000’-200’ = 4800’
 * The airport would indicate at the current settings on the altimeter as 800’ + 200’ = 1000’
 * And the AGL is 4800 – 800 or 4000’
 * Irregular distribution of oceans and continents
 * The relative effectiveness of differing surfaces in transferring heat to the atmosphere
 * Irregular terrain
 * Daily variations in temperature
 * The changes of seasons
 * Other factors
 * Isobars determine the direction of wind. Wind wants to move from High to Low pressure systems. As the distance increase, the forces are affected by the Coriolis Force, friction, gravity and the pressure gradient force.
 * If a pocket of air moves northward from a lower latitude to a higher latitude, because of its greater speed, it will move to the right of the point directly north of its initial starting point. This affects any migrating pocket of air moving North or South. A pocket of air moving south would encounter lag because it is entering a plane with a greater rim speed than the plane it left. Because of the lag, it would encounter the effect of a relative deflection to the right.
 * As wind speed increases, so does the strength of the Coriolis force.
 * The atmosphere is a large heat engine. It takes heat from the sun and converts the air about the surface causing wind. With the addition of the Coriolis Force, a single hemispheric cell breaks down into three cells: the tropical, the polar, and the less distinctive temperate or midlatitude cell.
 * Polar Easterlies – the cold dense high pressure system forms on the North Pole. This air spreads from the pole towards the equator and is deflected to the right resulting in a shallow layer of wind and form a belt of low pressure at 60° N
 * Prevailing Westerlies – the norther moving component of wing from the 30° N Lat is deflected to the right. It is one of westerly winds throughout the troposphere.
 * NE Tradewinds – The southerly moving component is deflected west becoming the very persistent NE widns from 30° N to the Equator
 * Air flows clockwise around High Pressure systems (anti-cyclonic) and counter-clockwise around Low Pressure systems (cyclonic)
 * Surface friction reduces the speed of the wind. Within 2000’ of the ground, the wind is force to go across the isobars from high pressure to low pressure.
 * If the wind is at your back, the area of lower pressure will be to your left. When standing on the earth’s surface the low will be slightly forward of directly left because the winds flow across the isobar
 * If you are facing toward a low, the wind will blow from your left to your right. So if you’re flying towards a low, you will drift you your right!
 * A narrow band of strong winds found most often in the vicinity of the tropopause. These winds average about 100-150 knots and may reach up to 250 knots. It must be 50 knots or greater to be a jet stream and core area must extend over considerable length.
 * Breezes created by the constant temperature surface of water’s body and the changing temperature of the land. During the day, the land is hot… causing uplift and pulling colder air off the ocean (Sea Breeze). During the night, the land is cooler causing an uplift of air in the ocean and the air moving from land to sea (Land Breeze)
 * During the day, mountain slopes heat through conduction. The air becomes warm and rises up to the colder slopes with higher altitude causing valley winds. At night, the air in contact with the slop is cooled and becomes denser than surrounding air and sinks causing Mountain winds.

Frontal Systems
2.50 Front and Frontogenesis 2.51 Front Characteristics 2.52 Polar Front 2.53 Atmospheric Discontinuities Across Fronts 2.54 Frontal Weather Factors 2.55 Cold Front Characteristics 2.56 Squall Lines 2.57 Warm Fronts 2.58 Stationary Fronts 2.59 Occluded Fronts 2.60 Upper Fronts 2.61 Inactive Fronts
 * Front – An area of discontinuity that forms between two contrasting air masses with sufficiently different temperature and moisture properties.
 * Frontogenesis – The formation of a new front or the regeneration of a decaying front that occurs when a relatively sharp frontal zone develops between two air masses whose properties contrast more and more over time.
 * Frontal cloud and precipitation patterns of most fronts are not recognizable above 15,000 feet. However, temperature and pressure gradients often extend into the troposphere. Winds usually shift 90° from one side of the front to the other. Speeds of warm fronts are usually 15 knots, and cold fronts move about 20 knots.
 * The polar front is the zone separating the warm tropical air masses and the cold polar air masses.
 * The four major properties that distinguish a front are the changing temperature, varying dew points, wind shifts and pressure gradients.
 * The five major factors that influence weather are the slope of the front, the spread of the frontal movement, the degree of stability of the lifted air, the amount of moisture available, and the temperature and moisture gradient.
 * A cold front is the leading edge of an advancing cold air mass. A cold front overtakes and uplifts the warm air mass creating violent unstable conditions, cumulonimbus clouds, thunderstorms and severe turbulence. Ahead of the front, the SW winds increase, the barometric pressure decreases and altocumulus clouds appear on the horizon. The cumulonimbus clouds move in and develop rain or snow showers, increasing in intensity as the front approaches. As the front passes, the pressure rises sharply, the wind shifts to the NE and the clouds clear rapidly. The temperature and the dew point decrease, and colder drier weather begins. Cold fronts generally move southeast at 20 knots.
 * A squall line is a nonfrontal line of violent thunderstorms. They usually develop 50 to 300 miles ahead of the cold front and run parallel to it. Squalls contain severe weather conditions such as thunderstorms, heavy rain, lighting, icing, heavy turbulence and hail or tornadoes. Squall lines are considered to be frontal weather.
 * A warm front is the leading edge of the advancing warm air mass that is overtaking and replacing a colder air mass. A warm front typically moves slower (15 knots) in a NE direction and tends to glide over the top of the colder air. The front is gradual and characterized by a sequence of clouds, beginning with cirrus, cirrostratus, then altostratus, nimbostratus, and then the low-lying stratus, with rain and fog. With the passage of a warm front, the winds change from the SE to the SW, and are followed by an increase of pressure and temperature.
 * A front that has no movement from one air mass toward the other. It is characterized by a pressure gradient and by a 180° shift in winds. The weather patterns of a stationary front are often very similar to the weather patterns of a warm front, but are usually less intense.
 * Occluded fronts occur when three fronts meet. It occurs when a cold front overtakes a warm front that is behind a cold front. The type of occlusion that develops depends on which front remains in contact with the earth. Occluded fronts generally align themselves to the north and south and move to the northeast at the speed of the front that is near the earth. The weather associated with the occlusion will be a combination of both types of frontal-weather. A cold front is an occlusion where the colder of the two cold fronts is the one overtaking the warm front. A warm front occlusion is an occlusion where the warmer of the two cold fronts is overtaking the warm front, and rising over the other cold front.
 * An upper front is a cold front aloft that moves over an even colder air lying in the lower layers of the atmosphere.
 * Inactive fronts do not create clouds or precipitation. This occurs when the fronts are too dry to form clouds. The front only has a shift in wind direction and pressure.

Thunderstorms
2.62 Requirements for Thunderstorm Formation 2.63 Thunderstorm Life Cycle Characteristics and Pressure 2.64 Types of Thunderstorms 2.65 Thunderstorm Hazards 2.66 Microburst 2.67 Microburst Characteristics 2.68 Tornadoes 2.69 Radar Assistance 2.70 Flying Near Thunderstorms
 * Lifting action, unstable air, high moisture content, and a cloud building through the freezing level.
 * Cumulus Stage – The initial stage is always a cumulus cloud. Updrafts extend the cloud upward, and snow and ice particles begin to develop and are carried upward into the cloud. High pressure exists throughout the cloud.
 * Mature Stage – The mature stage is reached when the raindrops and ice particles begin to fall. Downdrafts occur, expelling ice and rain. Strong vertical wind shears occur from simultaneous updrafts and downdrafts. Pressure varies throughout the cloud.
 * Dissipating Stage – The Dissipating stage occurs as updrafts begin to dissipate and the entire cell becomes an area of downdrafts with decreasing precipitation. Strong winds aloft may create the anvil seen in many thunderstorms. Wind and pressure are still greatly varied.
 * Frontal Thunderstorms – These are a result of the lifting of warm, moist, unstable air over a frontal surface. They normally form in lines and may contain stratus clouds with warm fronts, Cumulus clouds with Cold fronts, and both cumulus and stratus with occluded fronts.
 * Air Mass/Convective Thunderstorms – These are isolated thunderstorms that occur in warm, moist, unstable air and are not associated with fronts. They receive the necessary lifting through, thermal, convergence or orographic lifting.
 * Extreme turbulence, hail, microbursts, icing, lightning, and tornadoes.
 * A microburst is an intense highly localized downward atmospheric flow that emanates from a convective cloud, usually in the mid-afternoon of summer months.
 * Microbursts usually begin at the base of a cloud and spread out to areas over a two-mile expanse. They usually last 5 to 10 minutes and may develop in groups. The winds can be as low as 20 knots or exceed 200 knots. They may create vortex rings, or swirling areas of winds along the ground. Dry microbursts may occur under higher clouds that are providing no precipitation. High wind shear is associated with these phenomena.
 * An intense rotating column of air that protrudes from a cumulonimbus cloud in the shape of a funnel, rotating over the earth’s surface for anywhere from a few feet to hundreds of miles, travelling from 25 to 40 mph. Tornadoes are a little known about phenomenon and are very destructive. To form, they must have warm moist air near the earth’s surface, cold and dry air in the middle of the atmosphere, strong upper level winds, and the presence of Cumulonimbus clouds. The possible indications for the onset of a tornado are pronounced wind shear, rapidly moving cold front or squall line, strong convergence, marked convective instability, an abrupt change in moisture content and marked convection.
 * Radar can help to detect thunderstorm activity by bouncing radar waves off of the down falling precipitation to measure intensity.
 * Avoid them if possible and do not venture closer than 20 miles of mature storm clouds or anvils. If not possible, attempt to fly around the storm. If not possible, try to fly over the top, If not possible fly below the storm. If not possible fly through the lower 1/3 of the storm.

Turbulence
2.71 Intensities of Turbulence 2.72 Types of Turbulence 2.73 Thermal Turbulence 2.74 Cloud Formations and Thermal Turbulence 2.75 Mechanical Turbulence 2.76 Mountain Wave Turbulence 2.77 Flight in the Vicinity of Mountain Waves 2.78 Frontal Turbulence 2.79 Large Scale Wind Shear 2.80 Turbulence Avoidance
 * Light – Slight erratic changes in altitude.
 * Moderate – Greater intensity, but no loss of control.
 * Severe – Large abrupt changes in altitude, possible momentary loss of control of aircraft.
 * Extreme – Violent tossing and aircraft is nearly impossible to control. May cause structural damage.
 * Thermal (Convective) – Localized vertical convective currents due to surface heating or cold air moving over warmer ground.
 * Mechanical – Wind flowing over or around irregular terrain or other obstructions.
 * Frontal – Local lifting of warm air by cold air masses or the abrupt wind shift associated with most clod fronts.
 * Wind Shear – Resulting from a relatively steep gradient in wind velocity or direction producing eddies.
 * Vertical air movements resulting from convective currents develop in air that is heated by contact with a warm surface. This heating from below occurs when either cold air is moved over a warmer surface, or the ground is strongly heated by solar radiation.
 * The upper limits of the convective currents are often marked by haze lines or by the tops of cumulus clouds that form when the air is moist.
 * Movement of wind over an obstacle creates wakes or eddies on either side of the obstacle that can extend for miles beyond the surface that caused the turbulence.
 * When the air is stable, large waves form on the lee side of the mountain peaks and extend up into the stratosphere for up to 100 miles and downwind for up to 150 miles. Mountain wave turbulence is caused by the oscillation of the wind as it tries to return to the level that it was before it was lifted. Rotor clouds form at a lower level and are generally found at the same height as the mountain ridge. The cap cloud obscures both sides of the mountain peak. The lenticular clouds are stationary and above the height of the mountaintop.
 * Avoid turbulence by flying around the turbulence, or fly 50% higher than the height of the highest mountain range.
 * Avoid rotor, lenticular and the cap clouds.
 * Approach the mountain range at a 45° angle so that a quick turn can be made if a downdraft occurs.
 * Do not trust the altimeter; it may indicate altitudes 2,500 feet higher than your true altitude.
 * Penetrate turbulent areas at air speeds recommended for your aircraft.
 * Frontal turbulence is caused by lifting of warm air by a frontal surface leading to instability and/or wind shear between the warm and cold air masses.
 * Turbulent wind shear flight conditions are frequently found in the vicinity of the jet stream where large shears in both the horizontal and vertical planes are found as well as in association with land and sea breezes, fronts, inversions and thunderstorms.
 * Choose a cruising altitude away from the jet stream, avoid areas of rapidly shifting wind direction, and observe pilot and weather reports prior to flight.

Icing
2.81 Effects and hazards of Aircraft Icing 2.82 Supercooled water 2.83 Wet Snow avoidance 2.84 Requirements for the Formation of Structural Icing 2.85 Temperature Range for Structural Icing 2.86 Factors for Accumulation of Structural Icing 2.87 Anti-icing/Deicing equipment 2.88 Types of Structural Icing 2.89 Induction Icing, Compressor Icing and Fuel System Icing 2.90 Ground Icing Hazards 2.91 Conditions Associated with Air Masses, Fronts and Thunderstorms 2.92 Procedures to Minimize the Effects of Icing 2.93 Types and Intensities of Icing 2.94 PIREPS
 * It increases weight and drag, decreases lift and thrust and decreases performance. It disrupts the smooth flow of air over airfoils, decreasing lift and thrust and increasing drag and stall speed.
 * Liquid found at air temperatures below freezing. Usually found in clouds between 0 ° C an –15 ° C.
 * Climb to colder temperatures until encountering dry snow or descend to an altitude where temperatures are well above freezing.
 * Outside air temperature below freezing, aircraft skin temperature below freezing and visible moisture.
 * 0 ° C or colder. The most sever icing is encountered between 0 ° C and -10 ° C.
 * The size and number of water drops in a given volume of air, airfoil thickness, and airspeed. Larger airfoils, smaller drops and decreased airspeed reduce accumulation.
 * Deicing Boots and rubber bladders are installed on the leading edges of lift producing surfaces. They inflate/deflate in cycles, allowing ice to crack and peel off into the air stream. Anti-icing fluids are pumped through holes in the wing’s leading edge. Ground crews also use de-icing fluids.
 * Clear Ice – A transparent form of structural ice that forms through the slow freezing of large, super-cooled water droplets. It usually occurs between 0 ° C and -10 ° C.
 * Rime Ice – A milky white, opaque and granular deposit of ice formed through the rapid freezing of small super-cooled water droplets. It usually occurs between -10 ° C and -20 ° C.
 * Mixed Ice – A combination of rime and clear ice. It is the most common type.
 * Frost – A thin layer of crystalline ice that forms on exposed surfaces when the temperature of the exposed surface is below freezing and the dew point is below freezing. It can occur in flight as well as on the ground.
 * Induction Icing – Ice forming in the intake ducts during flight at temperatures above freezing, due to low pressure inside the ducts.
 * Compressor Icing – Ice forming on compressor inlet screens and compressor inlet guide vanes that restrict the flow of inlet air.
 * Fuel System Icing – Water mixed with jet fuel that freezes in the fuel lines.
 * Frozen precipitation or frost, wet aircraft coming out of hangers, water or slush splashed onto the aircraft, and ice or snow on the runways.
 * Air Mass Icing – Stable air masses produce stratus clouds with rime icing conditions. Unstable air masses produce cumulus clouds with clear icing conditions
 * Frontal Icing – Cold Fronts and squall lines generally have a narrow weather and icing band with cumuliform clouds and clear icing conditions. The most critical area is where water is falling from warm air above to a freezing temperature below causing clear icing conditions. Occluded fronts are the most erratic, causing clear mixed and rime ice.
 * Thunderstorm Icing – The worst icing conditions are encountered at and just above the freezing level, but can be encountered throughout the cloud at different stages of the thunderstorm.
 * Do not fly parallel to a front while encountering icing
 * Avoid the area below 4,000 feet around ridges in temperatures less than 0 ° C.
 * Do not make steep turns and avoid high angles of attack with ice on the airplane due to increased stall speeds.
 * Do not land with reduced power when the potential for ice on the wings and other exposed surfaces exists.
 * Do not forget that fuel consumption is greater under icing conditions, due to increased drag and power required.
 * Avoid icing conditions in the terminal phase of flight sue to reduced airspeeds.
 * Always remove ice and frost before attempting takeoff.
 * In stratiform clouds, you can often alleviate icing by changing altitude.
 * Trace – Perceptible ice formation, but not hazardous. No icing/deicing equipment is used.
 * Light – The rate of accumulation may create a problem if flight is prolonged in this environment. Use of icing/deicing equipment reduces/prevents accumulation.
 * Moderate – The rate of accumulation is potentially hazardous and use of anti-icing/deicing equipment is necessary for flight.
 * Severe – The rate of accumulation is such that deicing/anti-icing equipment fails to reduce or control the hazard.
 * Pilot reports are necessary because weather personnel often can not observe icing.

Ceilings and Visibility
2.95 Visibility Definitions 2.96 Sky Coverage 2.97 Obscuring Phenomena 2.98 Ceiling and Vertical Visibility 2.99 Relationship between Vertical Visibility, Obscuring Phenomena and a Ceiling 2.100 Fog 2.101 Four Requirements for Fog Formation 2.102 Wind and Fog 2.103 Types of Fog and 2.104 How They Dissipate
 * Visibility – The ability to see and identify prominent unlighted objects by day and prominent lighted objects by night. It is expressed in statute miles, hundreds of feet, or meters.
 * Flight Visibility – The average horizontal distance of visibility, as seen from the cockpit of an airplane in flight. It is measured in statute miles.
 * Prevailing Visibility – The greatest forward horizontal visibility equaled or exceeded throughout at least half the horizon circle. It is measured in statute miles.
 * Slant Range Visibility – The distance on final approach when you can see the runway.
 * Runway Visual Range (RVR) – The horizontal distance a pilot will see by looking down the runway from the approach end. It is expressed in hundreds of feet or meters.
 * Any collection of particles, such as haze, fog and smoke which reduce horizontal visibility to less than seven miles.
 * Ceiling – The height above the ground (AGL) with the lowest broken or overcast layer; or the vertical visibility into an obscuring phenomena.
 * Vertical Visibility – The distance that can be seen directly upward into an obscuring phenomena.
 * If the sky is totally hidden from view by a surface based phenomenon, the reported ceiling is determined by the vertical visibility upward as seen from the ground. When surface based obscuring phenomena present a slant range visibility problem they may also be classified as a ceiling.
 * Fog is a visible mix of small water particles that resides within 50 feet of the surface, is greater than 20 feet in depth and reduces vertical and horizontal visibility to less than 5/8 of a statute mile.
 * The air must have a high water content.
 * The temperature and dew point temperature must be equal.
 * Condensation nuclei must be present in the air.
 * Light surface winds must be present.
 * The horizontal motion of air next to the earth’s surface produces friction; friction causes the air near the ground to tumble, resulting in eddy currents. These currents mix the air sufficiently to cause a layer of air near the ground to reach a saturated state and produce fog or low clouds.
 * Ice Fog – A type of radiation fog that forms in moist air during extremely cold, calm conditions.
 * Steam Fog – An evaporation fog forming when cold air moves over warmer water. Steam Fog dissipates by heating the air through conduction.
 * Upslope Fog – Forms when orographic lifting causes enough adiabatic cooling to reduce the air temperature to the dew point temperature. Dissipation occurs when a wind shift pushes the air down the slope and causes adiabatic warming.
 * Radiation Fog – Fog formed due to the reduction of air temperature from nocturnal cooling. Radiation Fog is dissipated through winds of greater than ten knots or through heating of the earth and the consequent conduction.
 * Frontal/Precipitation Fog – Fog forming through the addition of moisture to air through the evaporation of rain or drizzle. Dissipation occurs with the passage of the frontal system of through cessation of precipitation.
 * Advection Fog – Fog forming as warm, moist air travels over a cold surface and the air cools below its dew point. It is dissipated through wind shift.

=Weather Exam Gouge=

1] Know the Tri-Cellular Theory Diagram.

2] Know how to convert gradient wind to surface wind
 * First step is to assign the gradient wind a cardinal point associated number.
 * Second step is to subtract 45 deg from it
 * Next give surface wind a cardinal point on the compass. (N, S, E, W or combo)

3] Define tropopause
 * Transition zone between the troposphere and the stratosphere; temp. is isothermal with altitude; an abrupt change in rate of temp. decrease with increasing altitude marks this boundary; it’s a region not a layer

4] Calculate sea level pressure
 * Example:
 * Given: Station Pressure = 27 inHg and Field Elevation 1500 ft
 * Find RAS
 * Known: 1 inHg decrease per 1000 ft
 * So: 1.5 inHg decrease per 1500 ft
 * Station Pressure is above Sea Level so we add 1.5 in Hg to 27 inHg to get Sea Level Pressure
 * Seal Level Pressure = 28.50 inHg

5] Know all 3 types of math problems Type 1 Average Lapse Rate:
 * Given: Point A ‡ temp = +2 deg C	Altitude = 6000 ft
 * Given: Point B ‡ temp = -8 deg C	Altitude = unknown
 * Find: Altitude at Point B
 * Change in Temp from A to B is –10 deg C
 * Temp decreases 2 deg C / 1000 ft
 * So, 10 deg C will occur in 5000 ft
 * Point B has a lower temp so it is higher
 * Add 5000 ft to Point A altitude of 6000 ft
 * Altitude at Point B is 11000 ft

Type 2 Reported Altimeter Setting
 * Given: Station Pressure = 28.20	Elevation = 4000 ft
 * Find RAS
 * Known: Pressure decreases 1 inHg/1000ft
 * So, Pressure decreases 4 inHg/4000ft
 * Add 4 inHg to station pressure to get RAS
 * RAS = 32.20 inHg

Type 3 Pressure Change vs. Altitude 6] What 3 elements are associated with moisture?
 * Given: Point A ‡ Pressure = 29.50 inHg
 * Given: Point B ‡ Pressure = 31.25 inHg		Elevation 1800 ft
 * Given: Assigned altitude = 4000 ft
 * Find: True Altitude at Point B?
 * Sing ditty: Hi to Low look out below, Low to Hi look up to the sky.
 * Choose appropriate relationship. In this case Low to Hi, so aircraft above altitude.
 * Change in Pressure is 1.75 inHg
 * 1.75 inHg occurs in 1750 ft
 * Known: Assigned altitude = 4000 ft
 * So: since aircraft is above altitude, true altitude is higher
 * Add 1750 ft to 4000 ft
 * True Altitude = 5750 ft
 * Find: AGL altitude over Point B?
 * Known: Elevation = 1800 ft
 * Thus, ground level is 1800 ft
 * Subtract 1800 ft (elevation) from your true altitude
 * AGL altitude = 3950 ft
 * Find: What does altimeter read at landing?
 * Change in Pressure is 1.75 inHg and produces a change of 1750 ft on your altimeter if you do not Kohlsman adjust
 * Known: Aircraft is above altitude
 * Aircraft elevation is 1800 ft
 * Subtract Pressure Change over 1750 ft from 1800 ft
 * Altimeter reads 50 ft.
 * Clouds
 * Humidity
 * Precipitation

7] What kind of drifts are associated with a high pressure area?
 * High pressure area, winds flow clockwise.
 * Fly into a high, you get right cross wind and left drift

8] What two forces cause winds to travel parallel to isobars?
 * Coriolis Force : bends gradient winds to the right, do not affect surface wind because of friction
 * Pressure Gradient Force : initiating force for all winds

9] Humidity definitions
 * Relative Humidity : percent of saturated air
 * Specific Humidity : Ratio of water vapor per unit mass of air. The higher the dew point the higher the specific humidity.

10] Difference between relative humidity and specific humidity 11] Two types of weather conditions that cause icing
 * Relative Humidity measures the percent of saturated air or what percentage of the bucket is filled with water
 * Specific humidity measures how much water vapor is contained per unit mass of air or how much water is in the bucket.
 * Supercooled water (freezing rain)
 * Wet snow

12] Know all 4 lifting actions and differentiate b/w them
 * Convergence : winds meet, cause air to move vertically
 * Orographic : wind runs into terrain, can’t go through, so it lifts air
 * Frontal : front moves in, so air has to move up
 * Thermal : sun heats land, land gives off heat, warm air rises

13] What are the three types of stability?
 * Stable : Air is pushed up until lifting action is removed, air is colder than the surrounding air, so it falls to its original position
 * Unstable : Air is pushed up until lifting action is removed, air is warmer than the surrounding air, so it is pushed up and continues to rise
 * Neutral : Air is pushed up until lifting action is removed, air is the same temp as the surrounding air and therefore it remains in place

14] Given lapse rate, state flight conditions or vice versa

15] What are the two types of shallow lapse rates?
 * Dry : temp. decreases 3 deg C / 1000 ft altitude increase
 * Moist : temp. decreases 1.5 deg C / 1000 ft altitude increase

16] Define air mass
 * A large body of air that has essentially uniform temp. and moisture conditions in a horizontal plan.
 * Source region never changes

17] Maritime vs. Continental
 * Maritime source region is most likely to produce clouds

18] Temp. in relationship with air and land
 * Air temp is relative to surface below it
 * Summer time, air masses are cold
 * Winter air masses are warm

19] Three parts of air mass classification
 * First is source region. A, P, T, E (Arctic, Polar, Tropical, Equatorial)
 * Second is surface of their source region. m or c (Maritime or Continental)
 * Third is temp. k (cold) or w (warm)

20] How to you get from Maritime to Continental?
 * m to c let out moisture
 * c to m need precipitation

21] Describe the two types of occlusions
 * Occlusions have three airmasses and two fronts

22]What are the general conditions of occlusions?
 * Combination of warm and cold fronts

23] Define Squall Line
 * A non frontal line of violent thunderstorms
 * Indicated by purple, dotted, dashed line

24] What is the worst hazard of squall line or thunderstorm?
 * Turbulence

25] What are the worst hazards of squall lines or thunderstorms?
 * Primary : turbulence
 * Secondary: hail

26] Know requirements for thunderstorm development
 * L		Lifting : most likely convergence
 * U		Unstable air
 * M		Moisture content in the air
 * B		Building clouds through the freezing level

27] Order of precedence when flying around thunderstorm
 * Go around
 * Fly over the top
 * Fly below
 * Fly through the lower 1/3

28] What weather conditions form tornadoes?
 * Marked convective instability
 * Pronounced horizontal wind shear
 * Rapid moving cold fronts or squall lines
 * Strong convergence

29] What is convective instability?
 * Dry air over Moist
 * Moist air over Dry

30] Everything about microburst
 * Definition: intense highly localized downdraft

4 Main Characteristics:
 * May emanate from any convective cloud
 * 2000 ft to 6000 ft per min downdraft
 * Occur mid-afternoon in the summer months
 * Last 5 to 10 minutes

Detection Sequential Effects: what the aircraft will feel/do as it enters/leaves microburst Entering: Leaving:
 * Visual cues : virga, dust, rain shafts w/ rain diverging from the core of the cell, roll clouds, lightning, torrential heavy rain showers
 * Wind Shear Alert Systems : NEXRAD, DOPPLAR, LLWAS (low level wind shear alert sys)
 * PIREPS : pilot reports
 * Departure / Arrival Weather Reports
 * First: Increase in Headwind
 * Second : Increase in AOA
 * Third : Increase in IAS
 * Fourth : Increase in Tailwind
 * Fifth : Decrease in AOA
 * Sixth : Decrease in IAS

31] What is mechanical turbulence?
 * Any irregular terrain. Could be mountains, buildings, whatever

32] Know everything that forms CAT and define CAT
 * Clear Air Turbulence: a non-convective form of windshear turbulence
 * Formed by jet streams
 * Formed by surface inversion                 ** all three are not required to form a CAT
 * Formed by mountain wave

33] Classifications of Turbulence
 * Light
 * Moderate
 * Severe
 * Extreme

34] Classifications of Icing
 * Trace
 * Light
 * Moderate
 * Severe

35] Define wind shear
 * Sudden change in wind direction and or speed over a short distance

36] What weather conditions form frost?
 * L	Little or no wind
 * L	Lack of clouds
 * A	AOT below freezing (temp)
 * D	Dew point within 5 deg C of air temp

37] At what temp does structural icing occur?
 * Below 0 deg C

38] What kind of ice does freezing rain cause?
 * Clear

39] What causes greatest change in Altimeter, Air Speed, and Rate of Climb?
 * Icing is greater than pressure
 * Affects are due to Pitot-Static clogs

40] Two types of fog and how to get it or get rid of it Get it by: 	Nocturnal or radiation cooling beginning around 1530 Get rid of it: 	Sunrise-Winds greater than 10 knots
 * Radiation Fog

Get it by:	Cold air over warm water Get rid of it:	Dissipates by heating the air through conduction-Winds greater than 10 knots
 * Steam Fog

41] Visibility Definitions
 * Visibility: the ability to see prominent unlighted objects by day and prominent lighted objects by night, expressed in statute miles.


 * Flight visibility: average forward horizontal distance measured in SM from the cockpit in flight


 * Prevailing visibility: greatest forward horizontal visibility, SM, equal or exceeded throughout at least half of the horizon circle, which need not be continuous


 * Runway Visual Range: horizontal distance a pilot will see by looking down the runway from the approach end


 * Slant Range visibility: distance on final approach when you can see the runway


 * Obscuring Phenomena: any collection of particles which will reduce horizontal visibility to less than 7 SM


 * Ceiling: height AGL to the lowest broken or overcast layer, or the vertical visibility into an obscuring phenomena


 * Vertical visibility: distance seen directly upward from the ground level into an obscuring phenomena

42] What causes saturation?
 * Cooling temp to dew point
 * Evaporations brings dew point to temp (adds moisture to air)

43] Sky coverage chart

=Coastie WX Questions=

Chapter 1 General Atmospheric Structure

 * Atmosphere
 * Atmospheric Composition
 * Atmospheric Layers
 * Where is there an abrupt change in the rate of temperature change?
 * Weather Elements
 * Weather Elements associated with moisture
 * Flight Hazards

Chapter 2 Atmospheric Temperature and Pressure
A/C is 1,000 ft lower than your Altimeter is actually reading or Your Altimeter reading will be 1,000 ft higher than where you are A/C really is? 1. What does your Altimeter indicate upon landing at Station B? 2. What is your true Altitude over Station B? 3. What is your AGL over station B?
 * Heat
 * Specific Heat
 * Insolation
 * Heat Transfer
 * Lapse Rates
 * Atmospheric Pressure
 * Standard Pressure
 * Sea Level Pressure, how do you calculate SLP?
 * Station Pressure
 * If station pressure is 26.00”Hg and field elevation is 1,700ft, then what is the RAS/LAS?
 * If you RAS/LAS is 28.50”Hg and field elevation is 1,500ft, then what is the station pressure?
 * If temperature at 10,000ft is *10 degrees C, using the SLR, what is your altitude if the outside air temperature is at +2 degrees C?
 * If your outside air temperature is at +4 degrees C at sea level, using the SLR, what is the altitude at *2 degrees C?
 * 1” decrease in pressure will mean what in relation to your aircraft?
 * Station A = 5,000ft at *11 degrees C, Station B = *5 degrees C, what is the change in altitude over station B? What is the Altitude over B?
 * Station A = RAS 30.5”Hg, A/C is at 15,000ft, Station B = RAS 29.00”Hg, Field Elevation is 4,000ft MSL
 * Isobars
 * Pressure Gradient
 * Isobar Spacing
 * Altitude
 * RAS or LAS
 * Rule of Thumb for transiting pressure and/or temperature regions
 * Types of Altitudes

Chapter 3 Winds and Their Circulation

 * Circulation
 * Influencing Factors
 * What causes winds to travel parallel to the Isobars?
 * Coriolis Force
 * Tri*Cellular Theory Diagram
 * Pressure Gradient Force
 * Gradient Winds and forces
 * Surface Winds
 * Buy’s Ballott Law and Application (drift/cross wind)
 * Gradient Wind Formula
 * If you have pressure gradient winds from the South what direction are the surface winds? Pressure gradient winds from the West?
 * If you have surface winds from the North what direction are the pressure gradient winds? Surface winds from the East?
 * Jet Stream
 * Breezes
 * Katabatic (downhill winds) Types

Chapter 4 Clouds and Moisture

 * What is saturation and how does it happen?
 * Dew Point Temperature (DPT)
 * Saturation
 * Relative Humidity
 * When does RH = 100%
 * What is Specific Humidity and how is it effected by dew point?
 * What is the difference between RH and SH?
 * Dew Pt Depression
 * Cloud Type * Cloud Description * Precipitation
 * Characteristics of Precipitation, Cloud, Description
 * Types of Precipitation
 * Cloud Formation

Chapter 5 Atmospheric Stability

 * Conditions of Stability
 * Free Convection
 * Adiabatic Process
 * What causes adiabatic cooling
 * Dry Adiabatic Lapse Rate
 * Moist Adiabatic Lapse Rate
 * Methods of Lifting and Examples
 * Environmental Lapse Rates(ELR) * Stability
 * If you have an Isothermal LR, what kind of clouds would you see?
 * If you have a Shallow LR, what kind of icing would have?
 * If you have poor visibility, what kind of Shallow Lapse rate would you have?
 * If you have gusty winds, what kind of laps rates could you have?
 * Conditional Instability
 * Convective Instability
 * Flight Conditions vs. Atmospheric Stability Chart

Chapter 6 Air Masses
a. cTw		b. mTk		c.cTk 		d. mTw
 * Air Mass
 * How do you classify of Air Masses
 * Describe each classification of Air Masses
 * How are Air Masses related to the surface beneath it?
 * How can an air mass change from c to m? m to c?
 * Maritime Polar Cold, Maritime Tropic Cold, Maritime Tropic Warm
 * Which air mass would be stable and most likely to produce stratform clouds and why?

Chapter 7 Frontal Systems

 * Front
 * Frontal Discontinuities
 * Frontogenesis
 * Influencing Front Factors
 * *Squall Line
 * What is another name for squall line?
 * What is the worst hazard for a squall line?
 * Stationary Fronts
 * Occlusion Diagrams
 * What type of icing would you get as you approached a WFO from the East/CFO from the West?
 * Frontolysis
 * Properties of Fronts Chart

Chapter 8 Thunderstorms

 * *Requirements for a thunderstorm formation
 * Stages or life cycle of a thunderstorm
 * Why can a thunderstorm go straight from Cumulus to Dissipating stage?
 * Gust Front/First Front
 * How do thunderstorms or squall lines effect the Barometer?
 * Types of Thunderstorms
 * Thunderstorm and Squall Line Hazards, 2 most important Hazards
 * *What are the main characteristics of microbursts?
 * How are microbursts detected?
 * Effects of an aircraft as it enters and leaves a microburst
 * Indications of tornado activity
 * Methods of detecting tornadoes
 * Which instruments are effected in thunderstorms and why?
 * What is considered the only reliable instrument in a thunderstorm?
 * Thunderstorm Flight Techniques

Chapter 9 Turbulence

 * Turbulence Classification
 * How is turbulence reported/explain the frequency?
 * Types of Turbulence
 * What type of land/type of turbulence produces the worst turbulence?
 * *What causes Mechanical Turbulence?
 * What effects the strength and magnitude of mechanical turbulence
 * What type of clouds form from mountain wave turbulence?
 * Condition and location of mountain wave turbulence
 * Mountain Wave Flight Rules
 * What causes frontal turbulence?
 * *Wind shear and causes?
 * *What is CAT?

Chapter 10 Icing

 * Structural icing and main consequences?
 * Super*cooled water, examples, and another name
 * Icing Temperature
 * Icing Requirements
 * Factors affecting rapid Accumulation
 * Types and most severe icing
 * *Frost and how does it occur?
 * Common Methods of Anti*Icing and De*icing Equipment
 * Which instruments does icing effect?
 * How do you detect icing?
 * Frontal Icing and cloud types/ice type
 * Thunderstorm Icing/Rime Ice
 * Reporting Icing

Chapter 11 Ceilings and Visibility

 * Visibility
 * Flight Visibility
 * Prevailing Visibility
 * Classification/Meaning/Sky Coverage
 * Obscuring Phenomena
 * Ceiling
 * Vertical Visibility
 * Fog Formation
 * Surface Winds
 * Radiation Fog appear/disappear
 * Steam Fog appear/disappear
 * Causes of Saturation