Weather_Test_deck Flashcards
(135 cards)
1
Q
Dry air consists of percentages of what three ingredients?
A
78% Nitrogen21% Oxygen1% Other gases
2
Q
In addition to the gases present in dry air, natural air contains a variable amount of ___ and ___.
A
Condensation NucleiWater Vapor
3
Q
Atmospheric circulation occurs in a three-cell pattern because of ___, ___, and ___.
A
uneven heating of the Earth’s surfacethe 23.5 degree tilt of the EarthCoriolis Force
4
Q
What is the Coriolis Force?
A
An apparent force developed by the unequal speed of rotation of Earth’s surface.
5
Q
The prevailing wind direction between the 30 and 60 degree latitudes moves FROM which direction?
A
The West
6
Q
The group of wind which moves our weather from west to the east are known as ___.
A
The prevailing westerlies
7
Q
What classification would describe a cold, dry air mass?
A
cP - continental Polar
8
Q
List the 4 types of heat transfer.
A
RadiationConductionConvectionAdvection
9
Q
How is heat transferred through the process of radiation?
A
by Electromagnetic Waves
10
Q
Describe the difference between Convection and Advection.
A
Convection - transfer of heat by way of gas (vertically)Advection - Horizontal transfer of heat by wind
11
Q
The standard temperature lapse rate is ___.
A
2 degrees per 1000’
12
Q
A layer of air, characterized by an increase in temperature with altitude, is referred to as a ___.
A
Temperature inversion
13
Q
What would prevent a radiation (nocturnal) temperature inversion?
A
Overcast skies (greenhouse effect)
14
Q
Cold, dense air lifting warmer, less dense air is an example of what type of temperature inversion?
A
Frontal
15
Q
What is the standard MSL pressure in inches of mercury and millibars?
A
29.92 Hg1013.2 hP/mb
16
Q
Sky conditions associated with low-pressure areas are normally produced by ___.
A
rising and cooling of the air
17
Q
What is an isobar?
A
Lines connection points of equal pressure corrected to sea level, usually spaced 4 mb apart.
18
Q
TRUE or FALSE. While flying parallel to the isobars above 2000’ AGL, the wind is approximately a head wind or tail wind and the pressure remains relatively constant.
A
TRUE
19
Q
The winds aloft or gradient wind circulation around a high pressure area is ___.
A
clockwise and parallel to the isobars
20
Q
Surface wind that converges to the center is associated with ___ areas, and the surface wind that diverges from the center is associated with ___ areas.What causes this shift in wind, flowing across the isobars rather than parallel the isobars?
A
low pressurehigh pressureSurface Friction
21
Q
You are flying a course of 045 with a steady crosswind from 135. Based upon the wind direction, what kind of pressure and general weather conditions would you expect ahead?
A
High pressure area with clear skies and weak pressure gradient force
22
Q
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 ___ than the indicated altitude.
A
lower
23
Q
Define Deposistion.
A
A direct change in moisture from a vapor to a solid
24
Q
A large temperature / dew point spread indicates ___ humidity.
A
low
25
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 temperature change is a result of the ___.
Adiabatic process
26
The level of Condensation (LCL) would occur where?
Air rising up a mountainside
27
The two basic types of clouds are ___.
Stratiform and Cumuliform
28
What type of cloud would indicate an unstable atmosphere?
Cumuliform
29
Clouds associated with the nocturnal cooling process would be ___.
low stratus and fog.
30
When the word nimbus is added to the names of a cloud, it means that ___.
some form of precipitation is associated with the cloud.
31
The primary cause of frontal weather is ___.
the lifting of warm air by colder air.
32
The frontal inversion of any front always slopes over the ___ air and the precipitation associated with it normally occurs in the ___ air.
coldcold
33
The type of air masses most often associated with fronts in the USA are ___ and ___.
Polar and Tropical
34
TRUE or FALSE. All fronts have temperature inversions.
TRUE
35
What four discontinuities (differences) must be present for the frontal symbol to be drawn on the weather chart?
TemperatureMoisture chart (dew point)Pressure change(fall then rise)Wind shift (approx. 90 degrees)
36
Define a cold front.
The leading edge of an advancing mass of cold air
37
The average speed of a cold front is about ___ knots and the average slope is ___.
25 to 35steep with an average ratio of 1:80
38
Cold fronts are usually associated with ___ clouds which tend to produce a ___ of clouds and pecipitation.
CumuliformNarrow-band
39
In which direction does a cold front move?
To the SE
40
The surface wind behind the cold front is generally ___ and the surface wind ahead of the cold front is typically ___.
NWSW
41
A severe line of thunderstorms, with destructive winds, possible hail and CB clouds, are called ___. They may form ahead of ___ moving cold fronts.
Squall LineFast
42
What is the flight procedure in the vicinity of a cold front?
Land and wait for the narrow band of weather to pass
43
Define a warm front.
The trailing edge of a retreating air mass of cold air, with warm air moving in behind the frontal symbol
44
The average slop of the warm front has a ratio of ___, and always slopes over the ___ air mass.
1:200cold
45
Warm fronts normally move to the ___.
NE
46
The surface wind behind a warm front generally blows from the ___ and the surface wind ahead of the warm front is usually from the ___.
SWSE
47
What type of weather is usually associated with a stable warm front?
a large area of ST, NS, AS clouds with rain and possible fog
48
Where would the weather, associated with a stable warm front, occur?
ahead of the warm front
49
What weather hazard should a pilot be aware of if the warm air being lifted by a warm front is unstable?
embedded thunderstorms and/or CB clouds
50
What are two important elements of preflight planning if your flight is in the vicinity of a warm front?
an alternate airport and proper fuel requirements (sufficient fuel)
51
The weather associated with a stationary front will normally be similar to that of a ___ front, but usually less intense.
warm
52
What is the average speed of a stationary front?
less than 5 knots
53
Wind associated with a stationary front usually flows ___ to the frontal symbol.
parallel
54
Stationary fronts may develop into ___.
frontal waves or open waves
55
Frontal waves (or open waves) may develop into ___.
Occluded fronts
56
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
57
Which front is considered to have the most violent weather?Why?
Occluded front (cold or warm) - The occluded front has both the cold and warm front weather occurring at the same location
58
If an occluded front symbol on a weather map is n 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.
ColdWarm
59
What is the procedure for flying in the vicinity of an occluded front?
Circumnavigate or land
60
List the four conditions necessary for the formation of radiation (and most other) types of fog.
Small temp/Dew point spreadAbundant Condensation NucleiLight surface windCooling land surfaces w/ warm air above
61
What are the dissipation factors for most types of fog?
HeatingStrong windGreenhouse effect (overcast skies)
62
Describe 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. This process is called radiation cooling.
63
Describe the formation and typical location of precipitation-induced fog.
Results from precipitation falling through cool, unsaturated air. Warm air is forced aloft until precipitation falls. Common ahead of warm front.Created as rain falls through a frontal inversion and saturates the cooler air below. It is typically found ahead of a warm front or behind a cold front.
64
The 2400L forecast report (TAF) for your destination airport predicts the sky CLR, wind at 4 knots, temperature of 17 degrees, and a dew point of 15 degrees. You will arrive at this destination shortly after midnight. What weather (by METAR coding) would you expect to encounter upon arrival?Assume the same conditions exist, but there were 12-15 knot winds. What kind of weather would you expect?
FGCLR, strong winds dissipate fog
65
Your December mission is taking you to Tyndall AFB, KPAM, along the Florida Gulf Coast. The ground is cold. Warm, moist air is flowing inland (at 3-9 knots) from the Gulf of Mexico. What type of fog would you expect to form? Would it cover a large or small area?
AdvectionLarge
66
Moist, stable air is being forced up an incline, expanding and cooling as it is lifted with wind speed greater than 10 knots. What type of fog will occur when this air reaches the saturation point?
Upslope Fog
67
Fog 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?
Greenhouse effect will slow the dissipation of fog by preventing insolation to heat the temperatures
68
What term describes the type of icing which is milky in color, granular in shape, and formed from small super-cooled water droplets?
Rime Ice
69
Clear icing will typically occur in cumulus clouds at temperatures between 0 - 16 deg. C where supercooled water droplets are ___ than those in stratiform clouds.
Larger
70
What intensity of icing would require immediate diversion from the affected altitudes?
Severe
71
Where is a common location to find freezing rain (during the winter months)?
Near warm fronts because of the shallow slope of the air mass
72
In addition to being a hazard to vision by covering windshields, ice can cause a loss of vital airspeed readings by covering the ___.
Pitot tubes
73
What 3 development factors are needed for a thunderstorm to form?
Unstable airHigh moisture content (small temp/dew point spread)Lifting actions (convections, orographic, and frontal)
74
What type of frontal thunderstorm would match the definition of "a severe line of thunderstorms that form ahead of a fast moving cold front"?
Squall Line
75
A summertime thunderstorm is building over your stage-field, just as it has done every day for the pas week about 3 pm. What type of thunderstorm is forming?
Air Mass thunderstorm
76
The windward side of the mountain range has vertical clouds developing into a thunderstorm. What type of thunderstorm is forming?
Orographic
77
The three stages of a thunderstorm, in the order of development are ___.
Cumulus, Mature, and Dissipating
78
The most turbulent weather would occur in which stage of a thunderstorm?
Mature
79
How do you know the cumulus stage as ended and the mature stage has begun?
Precipitation has started
80
What is the recommended flight procedure in the vicinity of an air mass thunderstorm caused by thermal convective activity?
Circumnavigate or land
81
The OWS Turbulence Chart is drawn for what category of turbulence?
Category II
82
TRUE or FALSE. If your aircraft is rated as a Category III (for turbulence purposes), the actual turbulence to be expected is less than what the OWS Turbulence Chart has forcasted.
TRUE
83
A microburst occurring in the heavy rain shaft of a thunderstorm would be classified as a ___ microburst.
Wet
84
A microburst with virga from under vertical clouds would be classified as a ___ microburst.
Dry
85
You receive an emergency mission to fly on Sunday afternoon, when your local military weather briefing office is closed. Who should you attempt to contact next for an official weather briefing?
The military Operational Weather Squadron (OWS) covering your area
86
How does relative humidity affect aircraft performance?
The lower RH indicates a small percentage of moisture in the air, fewer clouds, and better aircraft performance
87
What is the Dry air composition?
78% nitrogen21% oxygen1% other gases
88
What is the Natural air composition?
Dry air ingredients + condensation nuclei + water vapor
89
What does condensation nuclei consist of?
dust, smoke, and salt (hygroscopic)salt particles attract water vapor
90
In what layer of the atmosphere does weather occur?
The troposphere, where water vapor and nuclei are present
91
What are the three conditions affecting atmosphere circulation (the Three-Cell Theory)?
Uneven heating of the Earth's surfaceRotating Earth causing Coriolis ForceTilt of the Earth on its axis: causing seasonal changes
92
Define Air masses.
A large body of air whose physical properties (temperature and moisture) are horizontally uniform
93
Most air masses are designated as ___ systems and follow a path called air mass trajectory.
High pressure
94
Air masses are classified by Water Vapor Content and Temperature. What are the classifications?
c - Continentalm - MaritimeA - Artic (70 - 90 deg)P - Polar (40 - 60 deg)T - Tropical (10 - 30 deg)E - Equatorial (0 - 10 deg)
95
Define Temperature.
a measurement of heat energy. It describes the degree of molecular activity within a substance
96
Define Radiation (method of heat transfer) and the two types.
Transfer of heat by electromagnetic wavesInsolation - Incoming from the sun (short wave)Terrestrial - Outgoing from the earth (long wave)
97
Define Conduction (method of heat transfer).
transfer of heat by physical contact
98
Define Temperature Inversions.
When a layer within the troposphere increases in temperature with altitude (warmer air over colder air)
99
What are the two types of temperature inversions?
Radiation (nocturnal) inversions - happen on a cool, clear night as the ground releases the heat stored from throughout the dayFrontal inversions - happen when two air masses of different densities meet. The warm air is lifted by the cold air.
100
Define Atmospheric Pressure and what is the Standard MSL Pressure?
The force exerted by the weight of a column of air per unit area29.92" HG or 1013.2 mb/hP
101
Define Pressure Gradient Force.
Force exerted by a change in pressure per unit of horizontal distancealways acts from high to low pressure, perpendicular to the isobars
102
What is the difference between a strong and a weak pressure gradient force?
Strong - indicated by closely spaced isobars, called steep gradient force, results in strong winds, associated with low pressureWeak - indicated by widely spaced isobars, called flat pressure gradient force, results in light or calm wind, associated with high pressure
103
What are winds called above the friction level (2000' AGL)?Below the friction level?
Gradient Wind or Wind AloftSurface Wind
104
Define Buys Ballot's 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
105
What are the states of moisture?
Gas/Vapor - invisibleLiquid - visibleSolid - Visible, with structure
106
___ is exchanged as moisture changes from state to state.
Latent heat (hidden heat)
107
Define Evaporation.
Liquid changes to water vapor. The evaporating water vapor carries heat with it. This is known as the latent heat of evaporation.
108
Define Condensation.
Water vapor changes to liquid water. Occurs when air is saturated and impurities are present. Releases the latent heat of condensation.
109
Define Fusion (freezing)
The change of state from liquid to solid (releases heat)
110
Define Deposition
Process when vapor changes directly to solid. Vapor to solid releases heat. This process takes place below freezing temperatures.SKIPS LIQUID PHASE
111
Define Sublimation.
Process when solid changes directly to a vapor.SKIPS LIQUID PHASE
112
Define Melting.
Solid water (ice) changes to liquid.
113
What is the difference between Saturation and Dew Point?
Saturation - the air has all the water vapor that it can "hold" at that temperatureDew Point - the temperature to which the air must be cooled for it to become saturated and for a cloud to form
114
Define Relative Humidity.
The amount of water vapor in the air expressed as a percent, compared to what it could hold at that temperature.
115
The higher amount of moisture in the atmosphere would indicate a ___ air density (___ density altitude). A ___ relative humidity would decrease the performance of the rotor system.
lesserhighhigh
116
Define Adiabatic Process.
A process in which the temperature of a gas (air) is changed without the addition or deletion of heat energy.
117
Define Level of Condensation.
an altitude to which the air must be lifted for condensation to take place. Clouds will form at this altitude. Temperature and dew point are the same.
118
Define the following atmospheric stabilities:Stable - ___Unstable - ___Conditionally Unstable - ___
air that resists vertical movementair that starts moving vertically and will continue without any outside forceair that may be stable under one set of conditions and unstable under another
119
Cool, dry air is very stable and resists vertical movement. Air with ___ tends to be more unstable that dry air, if lifting action occurs.
high moisture content
120
Define Clouds.
extremely small condensed water vapor droplets suspended in the atmosphere
121
What are the 4 types of low clouds and what are their characteristics.
Cumulus - CU - flat bases, vertical building, indicate instabilityStratus - ST - low, uniform, sheet-like, horizontally-building, indicate stability,Stratocumulus - SC - large, dirty, gray cotton balls, build horizontally and vertically, indicate conditionally unstable airCumulonimbus - CB - top portion flat (anvil shape), vertical building, indicate unstable conditions.
122
What are the 3 types of middle clouds and what are their characteristics?
Altostratus - AS - sheets covering entire sky, signal arrival of warm front, little to no turbulence but may experience moderate icingAltocumulus - AC - patches "ripples" in sky, often signal change in weather in the next few hours, develops from dissolving altostratus or lifted cumulus, appear as layered cells and encountered at different altitudesNimbostratus - NS - dense and threatening, continuous periods of precipitation, generally extends downward into the low cloud ranges, horizontal building, but can vertically extend into a continuous cloud layer
123
What are the 3 types of high clouds and what are their characteristics?
Cirrus - CI - thin, feathery, whispy, connected with cirrostratus or altostratus may be a sign of approaching bad weather, tail is formed by precipitating ice crystals fallingCirrostratus - CS - Thin, whitish cloud layers appearing as a sheet or veil, usually signals approach of a warm front within 12 to 24 hours, stable layersCirrocumulus - CC - thin, closely spaced individual elements "cotton-balls", result from the lifting of a shallow unstable layer, "mackerel sky", signals upper level instability and can precede thunderstorms by up to 12 hours.
124
What kind of cloud would you expect at low altitude in an unstable environment?
Cumuliform clouds
125
What kind of cloud would you expect at low altitude in a stable environment?
Stratiform clouds
126
Define Fronts.
a boundary between air masses of different densities
127
What is the cause of frontal weather?
The primary cause of frontal weather is the lifting of warm moist air by colder, more dense air.
128
What are the 4 discontinuities which are used to locate and classify frontal locations?
TemperatureDew pointPressureWind shift
129
What is the average speed of a cold front?
25-35 knots
130
A stationary front is similar to what kind of front?
A warm front, but less intense
131
Where does a frontal wave develop (form)?
Most often forms from a stationary front
132
How does an Occluded front develop?
the result of a faster moving cold front overtaking (or catching up to) a slower moving warm front
133
What are the two types of occlusions?
Cold front occlusionWarm front occlusion
134
What are the flight considerations for the following fronts:Cold front / Squall line - ___Warm front - ___Stationary front - ___Frontal (Open) wave - ___Occluded front - ___
"don't go"ensure sufficient fuel for a long instrument flight and possible alternate airfieldsame as a warm fronthandle each individuallycircumnavigate or land
135
How can you recognize frontal passage:On the ground - ___In flight - ___
pronounced wind shift and change in air tempchanges are essentially the same thing
