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Every physical process of weather is accompanied by or is the result of

a heat exchange

Moisture is added to a parcel of air by

evaporation and sublimation

In the Northern Hemisphere, the wind is deflected to the

right by Coriolis force

Why does the wind have a tendency to flow parallel to the isobars above the friction level?

Coriolis force tends to counterbalance the horizontal pressure gradient

With regard to windflow patterns shown on surface analysis charts; when the isobars are

close together, the pressure gradient force is greater and wind velocities are stronger

What causes wind?

Pressure differences

Which is true regarding a cold front occlusion? The air ahead of the warm front

is warmer than the air behind the overtaking cold front

Which is true with respect to a high- or low-pressure system?

A high-pressure area or ridge is an area of descending air

Which is true regarding high- or low-pressure systems?

A low-pressure area or trough is an area of rising air

When flying into a low-pressure area in the Northern Hemisphere, the wind direction and velocity will be from the

left and increasing

While flying cross-country, in the Northern Hemisphere, you experience a continuous left crosswind which is associated with a major wind system. This indicates that you

are flying toward an area of generally unfavorable weather conditions

What prevents air from flowing directly from high-pressure areas to low-pressure areas?

Coriolis force

The general circulation of air associated with a high-pressure area in the Northern Hemisphere is

outward, downward, and clockwise

The wind system associated with a low-pressure area in the Northern Hemisphere is

a cyclone and is caused by Coriolis force

During the winter months in the middle latitudes, the jet stream shifts toward the

south and speed increases

The strength and location of the jet stream is normally

weaker and farther north in the summer

A common location of clear air turbulence is

in an upper trough on the polar side of a jet stream

The jet stream and associated clear air turbulence can sometimes be visually identified in flight by

long streaks of cirrus clouds

A strong wind shear can be expected

on the low-pressure side of a jetstream core where the speed at the core is stronger than 110 knots

Which type of jetstream can be expected to cause the greater turbulence?

A curving jetstream associated with a deep low-pressure trough

Which feature is associated with the tropopause?

Abrupt change in temperature lapse rate

What is the standard temperature at 10,000 feet?

-5°C

What are the standard temperature and pressure values for sea level?

15 °C and 29.92" Hg

What is the standard temperature at 20,000 feet?

-25 °C

Which is true regarding actual air temperature and dew point temperature spread? The temperature spread

decreases as the relative humidity increases

Which cloud types would indicate convective turbulence?

Towering cumulus clouds

Which combination of weather-producing variables would likely result in cumuliform-type clouds, good visibility, and showery rain?

Unstable, moist air and orographic lifting

Which are characteristics of a cold air mass moving over a warm surface?

Cumuliform clouds, turbulence, and good visibility

What is the approximate base of the cumulus clouds if the temperature at 2,000 feet MSL is 10°C and the dew point is 1°C?

6,000 feet MSL

What determines the structure or type of clouds which will form as a result of air being forced to ascend?

The stability of the air before lifting occurs

The presence of standing lenticular altocumulus clouds is a good indication of

very strong turbulence

Virga is best described as

streamers of precipitation trailing beneath clouds which evaporates before reaching the ground

Fog produced by frontal activity is a result of saturation due to

evaporation of precipitation

Which in-flight hazard is most commonly associated with warm fronts?

Precipitation-induced fog

A situation most conducive to the formation of advection fog is

an air mass moving inland from the coastline during the winter

Advection fog has drifted over a coastal airport during the day. What may tend to dissipate or lift this fog into low stratus clouds?

Wind 15 knots or stronger

In what ways do advection fog, radiation fog, and steam fog differ in their formation or location?

Radiation fog is restricted to land areas; advection fog is most common along coastal areas; steam fog forms over a water surface

What lifts advection fog into low stratus clouds?

Surface winds of approximately 15 knots or stronger

Which conditions are favorable for the formation of a surface based temperature inversion?

Clear, cool nights with calm or light wind

With respect to advection fog, which statement is true?

It can appear suddenly during day or night, and it is more persistent than radiation fog

What are the characteristics of stable air?

Poor visibility; steady precipitation; stratus clouds

Which would decrease the stability of an air mass?

Warming from below

Which would increase the stability of an air mass?

Cooling from below

What is a characteristic of stable air?

Stratiform clouds

Which is a characteristic of stable air?

Restricted visibility

Which is a characteristic typical of a stable air mass?

Continuous precipitation

What type weather can one expect from moist, unstable air, and very warm surface temperature?

Strong updrafts and cumulonimbus clouds

A moist, unstable air mass is characterized by

cumuliform clouds and showery precipitation

If clouds form as a result of very stable, moist air being forced to ascend a mountain slope, the clouds will be

stratus type with little vertical development and little or no turbulence

The formation of either predominantly stratiform or predominantly cumuliform clouds is dependent upon the

stability of the air being lifted

When an air mass is stable, which of these conditions are most likely to exist?

Smoke, dust, haze, etc., concentrated at the lower levels with resulting poor visibility

Which is true regarding the development of convective circulation?

Cool air must sink to force the warm air upward

When conditionally unstable air with high-moisture content and very warm surface temperature is forecast, one can expect what type of weather?

Strong updrafts and cumulonimbus clouds

Convective circulation patterns associated with sea breezes are caused by

land absorbing and radiating heat faster than the water

From which measurement of the atmosphere can stability be determined?

The ambient lapse rate

The difference found by subtracting the temperature of a parcel of air theoretically lifted from the surface to 500 millibars and the existing temperature at 500 millibars is called the

lifted index

The conditions necessary for the formation of stratiform clouds are a lifting action and

stable, moist air

What visible signs indicate extreme turbulence in thunderstorms?

Cumulonimbus clouds, very frequent lightning, and roll clouds

What feature is normally associated with the cumulus stage of a thunderstorm?

Continuous updraft

The conditions necessary for the formation of cumulonimbus clouds are a lifting action and

unstable, moist air

The most severe weather conditions, such as destructive winds, heavy hail, and tornadoes, are generally associated with

squall lines

Of the following, which is accurate regarding turbulence associated with thunderstorms?

Outside the cloud, shear turbulence can be encountered 20 miles laterally from a severe storm

Which statement is true concerning squall lines?

They offer the most intense weather hazards to aircraft

Which statement is true regarding squall lines?

They are nonfrontal and often contain severe, steady-state thunderstorms

Select the true statement pertaining to the life cycle of a thunderstorm

The beginning of rain at the Earth's surface indicates the mature stage of the thunderstorm

Which is true regarding the use of airborne weather-avoidance radar for the recognition of certain weather conditions?

The radarscope provides no assurance of avoiding instrument weather conditions

Which weather phenomenon signals the beginning of the mature stage of a thunderstorm?

The start of rain

During the life cycle of a thunderstorm, which stage is characterized predominately by downdrafts?

Dissipating

What minimum distance should exist between intense radar echoes before any attempt is made to fly between these thunderstorms?

40 miles

If airborne radar is indicating an extremely intense thunderstorm echo, this thunderstorm should be avoided by a distance of at least

20 miles

Which situation would most likely result in freezing precipitation? Rain falling from air which has a temperature of

more than 32°F into air having a temperature of 32°F or less

Which statement is true concerning the hazards of hail?

Hailstones may be encountered in clear air several miles from a thunderstorm

Hail is most likely to be associated with

cumulonimbus clouds

Ice pellets encountered during flight normally are evidence that

a warm front is about to pass

Ice pellets encountered during flight are normally evidence that

freezing rain exists at higher altitude

What is indicated if ice pellets are encountered at 8,000 feet?

Freezing rain at higher altitude

A pilot reporting turbulence that momentarily causes slight, erratic changes in altitude and/or attitude should report it as

light turbulence

When turbulence causes changes in altitude and/or attitude, but aircraft control remains positive, that should be reported as

moderate

Turbulence that is encountered above 15,000 feet AGL not associated with cumuliform cloudiness, including thunderstorms, should be reported as

clear air turbulence

The minimum vertical wind shear value critical for probable moderate or greater turbulence is

6 knots per 1,000 feet

One of the most dangerous features of mountain waves is the turbulent areas in and

below rotor clouds

The conditions most favorable to wave formation over mountainous areas are a layer of

stable air at mountaintop altitude and a wind of at least 20 knots blowing across the ridge

When flying low over hilly terrain, ridges, or mountain ranges, the greatest potential danger from turbulent air currents will usually be encountered on the

leeward side when flying into the wind

Convective currents are most active on warm summer afternoons when winds are

light

During departure, under conditions of suspected low-level wind shear, a sudden decrease in headwind will cause

a loss in airspeed equal to the decrease in wind velocity

During an approach, the most important and most easily recognized means of being alerted to possible wind shear is monitoring the

power and vertical velocity required to remain on the proper glidepath

What is an important characteristic of wind shear?

It can be present at any level and can exist in both a horizontal and vertical direction

Low-level wind shear may occur when

there is a low-level temperature inversion with strong winds above the inversion

Hazardous wind shear is commonly encountered

in areas of temperature inversion and near thunderstorms

If a temperature inversion is encountered immediately after takeoff or during an approach to a landing, a potential hazard exists due to

wind shear

The Low Level Wind Shear Alert System (LLWAS) provides wind data and software process to detect the presence of a

change in wind direction and/or speed within a very short distance above the airport

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