2Thunderstorms Conditions Stages Unstable air Lifting action High moisture contentStagesCumulus stage Mature stageDissipating stage
3Hazards Embedded thunderstorms may be obscured by cloud layers Wind shear can be found on all sides as well as directly under itGreatest intensity during mature stage, which is signaled by precipitation at the surface
4Types of Thunderstorms Airmass thunderstorms are usually isolated or scattered over a large areaFrontal thunderstorms associated with frontal activitySquall line is a narrow band of active thunderstorms normally containing severe weather
5Hazards Lightning is always associated with thunderstorms Hail is often associated with cumulonimbus clouds but can be found in clear area several miles from the cloudFunnel clouds - tornado or waterspout
6Thunderstorm Avoidance Use weather radar to avoid thunderstormsAvoid echoes by at least 20 miles - Do not fly between if less than 40 miles apartWeather radar does not pick up fog or clouds
8Mechanical Turbulence Wind forms eddies as it blows around hanger, stands of trees or other obstructions
9Convective Turbulence Thermal Turbulence is a daytime phenomena which occurs over land in fair weatherCapping stable layer begins at the top of the convective layer. It can be identified by a layer of cumulus clouds, haze or dust
10Frontal TurbulenceOccurs in the narrow zone just ahead of a fast-moving cold front
11Wake TurbulenceWingtip vortices occurs when an airplane generates liftThey can exceed the roll rate of an aircraftGreatest when an aircraft is heavy, slow and clean
12Wingtip VorticesTend to sink below the flight path of the generating aircraftMost hazardous during light, quartering tailwindsLand beyond where a large aircraft has touched down
13Wingtip VorticesLift off before the point a large aircraft departing in from of you lifted off climb out above his flight path or turn upwindHelicopters in forward flight produce wingtip vortices like circulation of air
14Clear Air TurbulenceTurbulence above 15,000 feet AGL not associated with cumuliform cloudiness is reported as CATCAT is common in a upper trough on the polar side of the jet stream
15Jet StreamA curving jet stream associated with a deep low pressure trough can be expected to cause great turbulenceJet stream can sometime be identified by long streaks of cirrus clouds
16Mountain Wave Turbulence Greatest turbulence occurs approaching the lee side of a mountain range in strong headwindsStanding lenticular and rotor clouds indicate the possibility of strong turbulence
17Reporting TurbulenceLight - slight erratic changes in altitude or attitudeModerate - aircraft remains in positive controlSevere - large abrupt changes in altitude and attitude and may be momentarily out of control
18Wind ShearSudden, drastic shift in wind speed and/or direction over a short distanceMay be associated with a strong low-level temperature inversion, a jet stream, a thunderstorm or a frontal zone
19MicroburstsIntense, localized downdrafts seldom lasting longer than 15 minutesDowndrafts can be as strong as 6,000 feet per minutePerformance changes drastically as an aircraft flies through a microburst
20Low-Level Wind Shear Systems LLWAS - system of anemometers compares wind speed at several locations around the airportTerminal Doppler Weather Radar provide a clearer, more detailed picture of a thunderstormVisual - Virga
21Restrictions to Visibility Fog, haze, smoke, smog and dustFog requires moisture and condensation nucleiIndustrial areas produce much fog since they have more condensation nuclei
22FogRadiation Fog - ground fog - forms over fairly flat land on clear, calm nightsAdvection fog- forms near coastal areas when moist air moves over colder ground or water
23FogUpslope fog forms when moist stable air is forced up a sloping land massSteam fog occurs as cool air moves over warmer waterPrecipitation-induced fog forms when warm rain falls through a layer of cooler air near the surface
24FogIce fog occurs in cold weather when the temperature is much below freezing and water vapor sublimates directly as ice crystals
25IcingFreezing rain is most likely to have the highest rate of accumulationIce, snow or frost having the thickness and roughness of sandpaper and reduce lift by 30% and increase drag by 40%
26Cold Weather Operations Preheat the cabin as well as the engine, but not at KSUWarm crankcase breather lines since they may be clogged by ice from vapors that have condensed and subsequently frozen
27I COMFog produced by frontal activity is a result of saturation due toA. evaporation of precipitation.B. adiabatic cooling.C. nocturnal cooling.
28I COMFog produced by frontal activity is a result of saturation due toA. evaporation of precipitation.
29I COMA situation most conducive to the formation of advection fog isA. a light breeze moving colder air over a water surface.B. an air mass moving inland from the coastline during the winter.C. a warm, moist air mass settling over a cool surface under no-wind conditions.
30I COMA situation most conducive to the formation of advection fog isB. an air mass moving inland from the coastline during the winter.
31I COMAdvection fog has drifted over a coastal airport during the day. What may tend to dissipate or lift this fog into low stratus clouds?A. Wind 15 knots or stronger.B. Nighttime cooling.C. Surface radiation.
32I COMAdvection fog has drifted over a coastal airport during the day. What may tend to dissipate or lift this fog into low stratus clouds?A. Wind 15 knots or stronger.
33I COMIn what ways do advection fog, radiation fog, and steam fog differ in their formation or location?A. Steam fog forms from moist air moving over a colder surface; advection fog requires cold air over a warmer surface; radiation fog is produced by radiational cooling of the ground.B. Advection fog deepens as windspeed increases up to 20 knots; steam fog requires calm or very light wind; radiation fog forms when the ground or water cools the air by radiation.C. Radiation fog is restricted to land areas; advection fog is most common along coastal areas; steam fog forms over a water surface.
34I COMIn what ways do advection fog, radiation fog, and steam fog differ in their formation or location?C. Radiation fog is restricted to land areas; advection fog is most common along coastal areas; steam fog forms over a water surface.
35I COMWith respect to advection fog, which statement is true?A. It can appear suddenly during day or night, and it is more persistent than radiation fog.B. It forms almost exclusively at night or near daybreak.C. It is slow to develop, and dissipates quite rapidly.
36I COMWith respect to advection fog, which statement is true?A. It can appear suddenly during day or night, and it is more persistent than radiation fog.