Aviation Weather Flashcards
Six basic elements of weather are the following:
- Temperature (warm or cold).
- Pressure.
- Wind (a vector with speed and direction).
- Moisture (or humidity).
- Clouds.
- Precipitation.
What is the composition percentage of dry air?
78% Nitrogen
21% Oxygen
1% Other Gases
What two additional ingredients does natural air have that dry air does not?
Condensation nuclei
Water vapor
Between the 30°- 60°N latitude is primarily where the U.S. is located. What is the prevailing wind
direction?
From the West
In which layer of the atmosphere does weather occur?
Troposphere
What is a cP?
c: Continental Air Mass (Dry Air)
P:Polar Air Mass (40-60)
(cold dry)
What are the characteristics of a cP?
Cold, dry air moving from the polar regions generally in southeast direction
Explain the difference between convection and advection.
Convection is the transfer of heat by way of gas (VERTICAL exchange of heat energy)
Advection is the HORIZONTAL transfer of heat by wind. (transfer of heat is greater than vertical transfer of heat)
In late evening, a thick layer of clouds have moved over your airfield.
WIll a (radiation) nocturnal inversion happen this evening? Why or why not?
No, the clouds will prevent an inversion from happening by keeping the warmer air near the surface
Define sea level pressure in two units of measurement.
29.92”
Hg (Inches of mercury)
1013.2
mb (millibars) or hP (hectopascals)
How is change in pressure depicted on a weather chart?
Isobars: Lines connecting points of equal pressure corrected to sea level, usually spaced 4mb apart.
What determines wind speed?
Pressure Gradient Force (PGF): Force exerted by a change in pressure per unit of horizontal distance.
Describe the wind speed at Location A and B.
Location A is strong winds
Location B is light winds
Isobars closely spaced – strong or steep pressure gradient, moderate to strong wind
Isobars widely spaced – weak or flat pressure gradient, calm or light wind
You’re on a true course of 010° and wind is from 280°. What type of weather conditions
should you expect?
Moving toward low pressure, lifting air, vertical clouds, turbulence, and possible storms.
Buys Ballot’ Law: Standing with your back to the wind, the low pressure will be to your __________________. Flying with a tailwind, the low pressure is on the _______ side of the aircraft.
Buys Ballot’ Law: Standing with your back to the wind, the low pressure will be to your left (Northern Hemisphere). Flying with a tailwind, the low pressure is on the left side of the aircraft.
(Classroom Left low door, right high door)
You’re departing Denver with an altimeter setting of 30.22. You arrive at New Orleans with an
altimeter setting of 30.00. You failed to reset your altimeter. Is your true altitude higher or lower than indicated?
Lower
How is flight performance affected by moisture in the atmosphere?
Less air density = higher density altitude = reduction in lift and reduction in engine performance
Which 3 atmospheric conditions provide for best lift?
High pressure
Low temperature
Low humidity
What kind of cloud would you expect at low altitude in unstable environment?
Cumuliform Clouds (Horizontal)
-Showery Precipitation
-Rough Air, Turbulence
-Good Visibility
What kind of cloud would you expect at low altitude in a stable environment?
Stratiform Clouds and Fog (Vertical)
-Continuous Precipitation
-Smooth Air
-Fair to Poor Visibility
During stagefield training and frontal passage, what would you expect to happen to wind
direction and speed?
What happens as warm air is lifted over a cold air mass?
Over the past several hours the altimeter setting at KOZR has been decreasing. Now, after
listening to ATIS, you notice the setting has increased. The wind is now blowing from the
NW and the OAT is showing a lower temperature. What has happened at KOZR?
Abbreviations or the following Low Level Cloud Bases within 6500’ AGL
Cumulus:
Stratus:
Stratocumulus:
Cumulonimbus:
Cumulus: CU
Stratus: ST
Stratocumulus: SC
Cumulonimbus: CB
CU: Cumulus
Low Level Cloud
ST: Stratus
Low Level Cloud
SC: Stratocumulus
Low Level Cloud
CB: Cumulonimbus
Low Level Cloud
Abbreviations for the following Middle Level Cloud bases between 6500’ and 20,000’ AGL.
Altostratus:
Altocumulus:
Nimbostratus:
Altostratus: AS
Altocumulus: AC
Nimbostratus: NS
AS: Altostratus
Middle Level Clouds
AC: Altocumulus
Middle Level Clouds
NS: Nimbostratus
Middle Level Clouds
Abbreviations for the following High Level Cloud bases between 16,000’ and 45,000’ AGL.
Cirrus:
Cirrostratus:
Cirrocumulus:
Cirrus: CI
Cirrostratus: CS
Cirrocumulus: CC
CS: Cirrostratus
High Level Clouds
CC: Cirrocumulus
High Level Clouds
In addition to the gases present in dry air, natural air contains a variable amount of ________ ________ and ________ __________
Condensation Nuclei
Water Vapor
The most important element of weather , usually not found above the troposphere, is _______ ________.
Water Vapor
Atomspheric curculation occurs in a three-cell pattern because of uneven heating of the Earth’s surface, the 23.5* tilt of the Earth, and ________ __________.
Coriolis Force
The prevailing wind direction between the 30* and 60* latitudes moves FROM which direction?
a. North
b. East
c. South
d. West
West
Which of the following would be a source region for a warm, moist air mass?
a. North Pacific Ocean
b. Northern Mexico
c. Siberia
d. Gulf of Mexico
Gulf of Mexico
What classification would describe a cold, dry air mass?
a. cP
b. mP
c. mT
d. cT
cP
List the four types of heat transfer.
Radiation
Convection
Conduction
Advection
How is heat transferred through the process of radiation?
Electromagnetic Waves
Describe the difference between convection and advection.
Convection is VERTICAL heat transfer
Advection is HORIZONTAL heat transfer
The standard temp. lapse rate is ____ C per 1000’.
2*
A layer of air, characterized by an increase in temperature with altitude, is referred to as a ________ __________.
Temperature Inversion
Cold, dense air lifting warmer, less dense air is an example of what type of temperature inversion?
a. Conduction
b. Frontal
c. Advection
d. Nocturnal
Frontal
What is the standard MSL pressure in inches of mercury and millibars?
a. 29.62 Hg and 1012.3 hP/mb
b. 20.72 Hg and 1013.1 hP/mb
c. 29.82 Hg and 1013.0 hP/mb
d. 29.92 Hg and 1013.2 hP/mb
d. 29.92 Hg and 1013.2 hP/mb
Sky conditions associated with low pressure areas are normally produced by?
a. sinking and warming of the air
b. sinking and cooling of the air
c. rising and warming of the air
d. rising and cooling of the air
d. rising and cooling of the air
What is an isobar?
Lines connecting point of equal pressure corrected to sea level, spaced 4mb apart.
While flying parallel to the isobars above 2000’ ft AGL, the wind is approximately a head wind or tail wind and the pressure remains relatively constant.
True or False?
True
The wind aloft or gradient wind curculation around a high pressure are is?
a. clockwise and perpendicular to the isobars
b. clockwise and parallel to the isobars
c. counter clockwise and parallel to the isobars
d. counter clockwise and perpendicular to the isobars
b. clockwise and parallel to the isobars
Surface wind that converges to the center is associated with (high / low) pressure areas, and surface wind that diverges from the center is associated with (high / low) pressure areas. What causes this shift in wind, flowing across the isobars rather than parallel the isobars?
Surface Friction
You are flying a course of 045* with steady crosswind from 135*. Based upon the wind direction, what kind of pressure and general weather conditions would you expect ahead?
a. High pressure are with low clouds, poor visibility and heavy rainfall
b. High pressure area with clear skies and weak pressure gradient force
c. Low pressure area with low clouds, poor visibility, and possible frontal activity
d. Low pressure area with clear skies and less pressure gradient force
b. High pressure area with clear skies and weak pressure gradient force
Flying on an easterly heading, you observe the aircraft drifting to the right. If you do not reset your altimeter as the flight progresses, you can expect the aircraft to be (higher / lower) than the indicated altitude
Lower
During stagefield training and frontal passage, what would you expect to happen to wind direction and speed?
Wind shift of 90* and wind speed will be affected by Gradient Force
What happens as warm air is lifted over a cold air mass?
It lifts, cools with altitude, condenses, creates clouds, and “makes weather”
Over the past several hours the altimeter setting at KOZR has been decreasing. Now, after listening to ATIS, you notice the setting has increased, the wind is now blowing from the NW, and the OAT is showing a lower temperature. What has happened at KOZR?
A cold front has already passed
The cold front is moving faster than previously forecast. What type of weather would you expect ahead of the front?
Squall Line Formation
The entire local flying area is covered in ST, NS, and AS clouds. What type of front is occurring?
Stable Warm Front
You are approaching the clouds in the following order: CS, AS, and NS. What changes in ceiling, visibility, and chance of precipitation can you expect?
Ceiling and visibility start to decrease and precipitation will increase
Which term belongs with the definition “A direction change in moisture from vapor to a solid”?
a. Condensation
b. Deposition
c. Evaporation
d. Sublimation
b. Deposition
A large temp/dewpoint spread indicates (high / low) relative humidity.
Low
Air being lifted over a mountain range will cool on the windward side and heat up as it moves downslope on the leeward side. This temp change is a result of the…
a. thermal currents
b. cold and warm air advection
c. cold mountaintops
d. adiabatic process
d. adiabatic process
The Lifted Condensation Level (LCL) would occur where?
a. Air rising up a mountainside
b. The valleys beyond the mountains
c. Air descending from the mountain top
d. Air undergoing adiabatic warming
a. Air rising up a mountainside
The two basic types of clouds are?
a. stratus and stratocumulus
b. cumulus and cumulonimbus
c. stratiform and cumuliform
d. altocumulus and cirrostratus
c. stratiform and cumuliform
What type of cloud would indicte an unstable atmosphere?
Cumuliform
Clouds associated with the nocturnal cooling process would be?
a. cirrus
b. cumulus
c. low stratus and fog
d. altocumulus
c. low stratus and fog
What do the symbols at A, B, and C represent?
A. Warm Occlusion
b. Warm Front
c. Cold Front
Why is the occluded front considered more complex than the others?
It is a combination of both cold and warm front weather
When the word nimbus is added to the names of a cloud, it means that…
a. some form of precipitation is associated with the cloud
b. the cloud system had its base above 6,5000ft
c. th cloud was caused by local convective currents
d. the cloud has vertical development and ice crystals at the top
a. some form of precipitation is associated with the cloud
What is the flight procedure in the vicinity of image A and B?
Circumnavigate or land
What type of cloud is described?
Middle altitude, stable, horizontal cloud producing rain.
NS: Nimbostratus
What type of cloud is described?
Low altitude, unstable, vertical cloud without precipitation.
CU: Cumulus
What type of clouds are described?
Low altitude, unstable, vertical cloud producing rain, possible hail, icing and LTG.
CU: Cumulonimbus
What type of cloud is described?
Low altitude, stable, horizontal cloud without rain.
ST: Stratus
The primary cause of all frontal weather is…
a. the lifting of cold air by warmer air
b. the lifting of warm air by colder air
a. the lifting of cold air by warmer air
All fronts have temperature inversions.
True/False
True
What four discontinuities (differences) must be present for the frontal symbol to be drawn on the weather chart?
-Temperature
-Moisture Content
-Pressure
-Windshift
The average speed of a cold front is about _________ knot and the average slope is (steep with a ratio of 1:80 / shallow with a ratio of 1:200).
25-35 kts
steep with a ratio of 1:80
Cold fronts are usually associated with (cumuliform / stratiform) clouds which tends to produce a (narrow-band / wide-spread area) of clouds and precipitation.
Cumuliform
Narrow-band
In which direction does a cold front move? (Frontal movement is always reported TO a direction)
South East
The surface wind behind the cold front is generally _____ (from which direction) and the surface wind ahead of the cold front is typically _____ (direction). (Wind is always reported FROM a direction.
NW
SW
A severe line of thunderstorms, with destructive winds, possible hail and CB (Cumulonimbus) clouds, are called _______ ________. They may form ahead of (slow / fast) moving cold fronts.
Squall Line
fast
What is the flight procedure in the vicinity of a cold front?
Fly around by 50NM E/S/W and 200NM North
The average slope of the warm front has a ratio of 1:200, and always slopes over the (cold / warm) air mass.
1:200
cold
Warm fronts normally move TO the ____ (in which direction).
NE
The surface wind behind a warm front generally blows FROM the ___ (direction) and the surface wind ahead of the warm front is usually FROM the ____ (direction).
SW
SE
What type of weather is usually associated with a stable warm front?
a. narrow band of CU and CB clouds along with severe thunderstorms
b. squall line thunderstorms forming ahead of the slow moving warm front
c. a large area of ST, NS, AS clouds with rain and possible fog
d. a large area of CI, AS, and CU clouds with light snow and ice
c. a large area of ST, NS, AS clouds with rain and possible fog
According to the cloud sequence below, indicating a shallow slope, you are approaching a stable (warm / cold) front from the (warm / cold) air side.
warm
cold
Where would the weather, associated with a stable warm front, occur?
a. ahead of the warm front
b. behind the warm front
c. 80 miles behind the warm front, with a break of weather possible in between
a. ahead of the warm front
What weather hazard should a pilot be aware of if the warm air being lifted by a warm front is unstable?
Embedded thunderstorms
The weather associated with a stationary front will normally be similar to that of a (cold / warm) front, but usually less intense.
warm
What is the average speed of a stationary front?
0-5knts
Wind associated with a stationary front usually flows (parallel / perpendicular) to the frontal symbol.
parallel
Stationary fronts may develop into frontal waves. Frontal waves (sometimes called open waves) may develop into (cold / warm / occluded) fronts.
occluded
What type of front develops when the faster moving cold front of a frontal wave catches up with the slower moving warm front of the wave?
Occluded front
Which front is considered to have the most violent weather?
Why?
Occlusions
They combine weather from warm and cold fronts
If an occluded front symbol on a weather map is an extension of the cold front symbol, it is a ____ type occlusion. If an occluded front symbol is an extension of the warm front symbol, it is a _____ type occlusion.
cold
warm
What is the procedure for flying in the vicinity of an occluded front?
Circumnavigate or Land
Describe the formation of advection fog?
Warm, moist air flowing over a cooler surface
Prevailing wind blowing from a large body of water over a colder land surface
What type of fog would be expected as air is lifted on the windward side of a mountain?
Upslope Fog
Name three hazards of icing.
-Loss of ability to autorotate
-Reduces lift
-Increases drag and weight
-Reduces the speed at which the rotorblade will stall
-Reduces visibility when ice forms on windshield
-Reduces airflow to engines when ice forms on screens
-Pitot and/or static source icing results in instrument error
Where would be a likely frontal location to find freezing rain?
Near warm fronts
What altitudes would be affected by severe clear ice?
AGL or MSL?
10,000-18,000’ MSL
A flight has been planned for 4000’ from KOZR to KTOI in late November. Just before going to the aircraft, a PIREP from another aircraft shows they experienced severe clear icing at 3,500’ near KTOI. Does this affect your planned flight?
Yes, so you can change the altitude to avoid the known icing
An OWS Turbulence Chart shows “moderate” turbulence in your flying area. If you were flying a Category I aircraft, would the turbulence be greater or less than “moderate”?
Greater than moderate
List the conditions conducive to a wet microburst.
Cumulus clouds with heavy rain
What are the four types of fronts shown below?
Cold front
Warm front
Stationary front
Occluded front
List the four conditions necessary for the formation of radiation (and most other) types of fog.
a. High moisture content
b. Abundant Condensation Nuclei
c. Light surface wind
d. Cooling land surface w/warm air above
What are the dissipation factors for most types of fog?
a. Heating
b. Strong wind
c. Greenhouse effect/overcast sky
Discribe the formation of radiation fog.
At night, terrestrial radiation cools the surface of the earth. The surface cools lower layers of air to the dew point.
Describe the formation and typical location of precipitation-induced fog.
When warm air forced aloft until precipitation falls. Ahead of warm front and behind cold front.
The 2400L forecast report (TAF) for your destination airport predicts the sky CLR, wind at 4 knts, temps of 17, and dew point 15. You will arrive at this destination shortly after midnight. What weather (by METAR coding) would you expect to encounter upon arrival?
a. CLR
b. FG
c. TSRA
d. FZRA
b. FG
The ground is cold. Warm, moist air is flowing inland at 3-9kts from the Gulf of Mexico. What type of fog would you expect to form?
____________
Would it cover a large or small area?
_____________
Advection
Large
Moist, stable air is being forced up an incline, expanding and cooling as it is lifted with wind speed greater than 10kts. What tpe of fog will occur when this air reaches the saturation point?
Upslope Fog
For has formed during the late evening hours. Before sunrise, a thick overcast layer of clouds moves in over the fog. What effect will this have on the dissipation of this fog?
It will slow the dissipation of fog
What term descibes the type of icing, which is milky in color, granular in shape, and formed fro small super cooled water droplets?
Rime Ice
Clear icing will typically occur in cumulus clouds at temps between 0C and -16C where supercooled water droplets are (larger / smaller) than those in stratiform clouds.
larger
What intensity of icing would require immediate diversion from the affected altitudes?
Severe
Where is a common frontal location to find freezing rain (during the winter months)?
Warm fronts
In addition to being a hazed to vision by covering windshields, ice can cause a loss of vital airspeed readings by covering the _______________
Pitot/Static Source
What type of weather would you expect near the High Pressure system 1033?
a. Lifting air, OVC skies, strong pressure gradient force
b. Sinking air, CLR skies, weak pressure gradient force
c. Sinking air, OVC skies, strong pressure gradient force
d. Lifting air, CLR skies, weak pressure gradient force
b. Sinking air, CLR skies, weak pressure gradient force
From which direction would you expect the wind at the High Pressure system 1033?
North west
Choose the factors needed for a thunderstorm to form.
a. Conditionally unstable air, strong wind, large temp/dep point spread
b. Unstable air, light wind, OVC cloud layer
c. Unstable air, large temp/dew spread, frontal lifting
d. Unstable air, small temp/dew point spread, lifting action
d. Unstable air, small temp/dew point spread, lifting action
What type of frontal thunderstorm would match the definition of “a severe line of thunderstorms that form ahead of fast moving cold front”?
Squall Line
A summertime thunderstorm is building over your stage field, just as it has done every day for the past week about 1500. What type of thunderstorm is forming?
Air mass thunderstorm
The windward side of the mountain range has vertical clouds developing into a thunderstorm. What type of thunderstorm is forming?
Orographic Thunderstorm
The three stages of a thunderstorm, in the order of development, are _______________, ______________, and ________________.
Cumulus Stage
Mature Stage
Dissipating Stage
The most turbulent weather would occur in which stage of a thunderstorm?
Mature stage
How do you know the cumulus stage has ended and the mature stage has begun?
When precipitation has started and downdrafts
What is the recommended flight procedure in the vicinity of an air mass thunderstorm cause by thermal convective activity?
Avoid by circumnavigated by at least 20NM or land
The OWS turbulence chart is drawn for what category of aircraft?
CAT II
If your aircraft is rated as CAT III (for turbulance purposes), the actual turbulance to be expected is less than what the OWS turbulance chart has forecasted.
True or False
True
A microburst occurring in the heavy rain shaft of a thunderstorm would be classified as a 9wet / dry) microburst.
wet
A microburst with virga from under vertical clouds would be classified as a (wet / dry) microburst.
dry
