Weather Theory Flashcards
Air travels which direction around a high pressure system?
Clockwise
In a low pressure system air circles which direction due to the Coriolis Force?
Counter clockwise
What are the three stages of a thunderstorm?
What’s happening in each stage?
Cumulus - lifting action of the air begins
Mature - rain or ice begin falling
Dissipating - top of cloud spreads out, downdrafts spread out and replace updrafts needed to sustain the storm and the cell dies
What is the most violent stage of this thunderstorms life cycle?
Mature stage
A good rule of thumb is to circumnavigate thunderstorms identified as ________ or giving an _________ _______ ______ by at least _____ since _____ may fall for ______ outside of the clouds.
severe
extreme radar echo
20 NM
hail
miles
What are the three conditions required for the formation of thunderstorms?
- Sufficient water vapor
- Unstable lapse rate
- Initial lifting action
Some thunderstorms occur at random in unstable air, last for only an hour or two, and produce only moderate wind gusts and rainfall. These are known as what?
They are generally a result of…
Air mass thunderstorms
surface heating.
This type of thunderstorm is associated with weather systems (fronts, converging winds, troughs aloft) forcing upward motion that often form into squall lines. In the mature stage, updrafts become stronger and last much longer than in air mass thunderstorms, hence their name.
Steady-state thunderstorms
What are the hazards associated with thunderstorms?
THIS LLWS H
- Tornadoes
- Hail
- Icing
- Strong updrafts, downdrafts
- Limited visibility
- Lightning
- Wind shear
- Severe turbulence
- Heavy rain
Cumulus clouds are formed in ________ air and look fluffy or bumpy.
unstable
Stratus clouds are formed in ________ air and look stratified or layered.
stable
Nimbo or nimbus means ______ cloud.
rain
High clouds are found between 16,500 feet and 45,000 feet in the middle latitudes and are called ________ clouds.
Name 3 types.
C
A
S
cirriform
Cirrus
Cirrocumulus
Cirrostratus
Middle clouds exist between 6,500 feet and 23,000 feet in the middle latitudes and are usually prefixed with _____ and include ___________ and ____________.
C
A
S
alto
altostratus
altocumulus
Low clouds extend from the surface to about 6,500 feet and include _______, ______________, and ___________.
C
A
S
stratus
stratocumulus
nimbostratus
Clouds with extensive vertical development may extend from 1,000 feet above the surface to as high as 60,000 feet include ________ and ____________ (thunderstorms) if they contain _____.
cumulus
cumulonimbus
rain
A front is the boundary between two ___ _____ with different ____________.
air masses
temperatures
A cold front occurs when advancing _____ air displaces _____ air.
cold
warm
A warm front occurs when advancing _____ air displaces a _____ air mass.
warm
cold
A stationary front occurs when the frontal movement is less than __ knots.
5
When a fast-moving cold front lifts a warm air mass completely off the ground and overtakes cool air in front of the warm air mass.
Cold front occlusion
When a fast-moving cold front lifts a warm air mass completely off the ground and the cold air mass ahead is the coldest of the three air masses.
Warm front occlusion
What are the types of fog?
Radiation fog
Advection fog
Ice fog
Upslope fog
Steam fog
Precipitation-induced fog
Fog is a ______ that begins within ___ feet of the surface
cloud
50
Radiation fog occurs on _____, _____ nights when the ground ______ rapidly due to the release of ground _____ (radiation).
calm, clear
cools
heat
Advection fog occurs when _____, ______ air moves over a _____ surface. Winds are ________ for advection fog to form.
warm, moist
cold
required
Upslope fog occurs when moist, ______ air is forced up a terrain slope and _______ down to its dew point by adiabatic cooling.
stable
cools
Steam fog occurs when _____, dry air moves over _____ water. __________ is added to the airmass and steam fog forms.
cold
warm
Moisture
Ice fog forms when the temperature is below _________ and water vapor turns directly into ___ crystals.
freezing
ice
What are the 3 types of fog that require wind to form?
Advection fog
Upslope fog
Steam fog
Fog occurs when the air temperature near the ground reaches its ____ point, or when the dew point is ________ to the existing temperature by added _________ to the air.
dew
raised
moisture
Wind shear is a sudden _______ in _____.
Can be horizontal or _________.
Occurs over a short _________ or short period of ______ and ______
change
wind
vertical
distance
time
speed
A microburst is a small-scale intense __________ produced by some thunderstorms. Spreads strong surface winds in all _________ and produces horizontal and vertical _____ ______.
downdraft
directions
wind shear
Virga is rain that does not reach…
the ground
Lenticular clouds are lens-shaped clouds that form at the crest of mountain ______ and can form with stable air and winds of ___ knots or more.
waves
40
What causes turbulence?
Wind shear
Clear air turbulence is defined as turbulence above ______ feet, in clear ___, and not associated with ________ activity.
15,000
air
convective
In what weather condition will you have the highest accumulation rate of aircraft structural ice?
Freezing rain
An elongated area of high pressure is a _______. An elongated area of low pressure is a ________ and indicates potential…
ridge
trough
showers and thunderstorms
Name each type frontal symbol
Warm
Cold
Stationary
Occluded
What are the 3 kinds of structural icing?
Clear
Rime
Mixed
What two conditions are required for the formation of structural icing?
- Visible moisture
- Aircraft surface temperature below freezing
Clear ice forms when large __________ water drops ______ slowly as a ______ sheet of solid ice.
supercooled
freeze
smooth
Rime ice is opaque, ______, _______ ice formed by ______ supercooled water drops freezing quickly.
white, rough
small
What is mixed ice?
Clear ice and rime ice formed simultaneously
What is the most dangerous type of ice?
Clear ice
You can expect stable air to have ________ clouds, ______ visibility, ______ air, and _______ or _________ precipitation.
Unstable air will produce ________ clouds or clouds with ________ development, _____ visibility, _________, and __________ precipitation.
stratiform
good
smooth
steady or continuous
cumuliform
vertical
poor
turbulence
showery
Precipitation-induced fog occurs when relatively ______ rain or drizzle falls through _____ air and _________ from the ___________ saturates the ______ air
warm
cool
evaporation
precipitation
cool
Precipitation-induced fog occurs when relatively ______ rain or drizzle falls through _____ air and _________ from the ___________ saturates the ______ air
warm
cool
evaporation
precipitation
cool
