Final Exam Aviation meter

The friction layer is the layer of wind closest to the earth's surface whose speed is slowed by contact with the earth's surface, trees, hills, obstructions, etc. The average height of this layer, above which the friction of the earth is no longer a factor in the speed of the wind, is about

3000 - 5000 feet above the ground

The force exerted by a mass of air above a given point over a given surface area, usually expressed in millibars (mb), inches of mercury ("Hg), or hectopascals (hPa), is known as

Air pressure

What month usually produces the most violent tornadoes?

April

An exceptionally dense and vertically developed cloud, associated with thunderstorms, and often with a top shaped like an anvil, is called a ______cloud.

Cumulonimbus

List the 3 stages, in order, of an ordinary cell thunderstorm life cycle.

Cumulus, mature, dissipating

A______is a boundary between a cold downdraft (that comes out of a thunderstorm) and warm, humid, surface air.

Gust front

During the ______stage (initial occlusion), a middle latitude cyclone is usually at its most intense state.

Mature

What month usually has the highest number of tornadoes?

May

A______is a strong, localized downdraft less than 4km (2.5 miles) wide that occurs beneath thunderstorms

Microburst

The______also known as the Norwegian Cyclone Model, gave the world a working model of how a mid-latitude cyclone progresses through the stages of birth, growth, and decay along the polar front.

Polar Front Theory

The force caused by horizontal differences in pressure within the atmosphere that causes air to move and, hence, the wind to blow is called the ______

Pressure Gradient Force

The wind direction most frequently observed during a given period at a given location is known as the ______wind

Prevailing

______thunderstorms (sometimes called "pop-up" thunderstorms) that form in the summer are referred to as "ordinary cell thunderstorms" or "air-mass thunderstorms" because they tend to develop in warm, humid air masses, away from significant weather fronts.

Scattered

A______is a line of thunderstorms that forms along a cold front or out ahead of it.

Squall line

______thunderstorms (consisting of a single, rotating updraft) are usually much larger than the ordinary cell thunderstorm.

Supercell

When upper-level divergence is greater than surface convergence (more air is taken out at the top than is brought in at the bottom) over a particular low pressure area, what happens to the pressure at the surface?

Surface pressure decreases, deepening the low

The area of the United States where the greatest annual average of tornadoes occur is in the central plains from Texas to Nebraska. This area is known as______.

Tornado alley

A______is a series of tornadoes (typically 6 or more) that forms within a particular region that may include several states and is often associated with widespread damage and destruction.

Tornado outbreak

The United States is not a good source region for air masses.

True

Which of the following is the greatest danger to an aircraft that flies into a thunderstorm - heavy rain, lightning, turbulence, or visibility?

Turbulence

Why do hurricanes initially form only in the tropics?

Warm water temperatures are found there

A tornado______is issued when a tornado has been spotted visually or indicated on weather radar.

Warning

A tornado______is issued when atmospheric conditions are favorable for tornadoes to develop in a particular region during a certain time period.

Watch

Match each wind circulation scale with the correct example of each:

__3__ circulation around a low along a front Incorrect Response __2__ seabreezes Incorrect Response __4__ circulation around the Bermuda High __1__ eddies 1. microscale 2. mesoscale 3. synoptic scale 4. planetary (global) scale

Match the air masses with their proper characteristics (must get all correct):

__4__ maritime polar (mP) __5__ maritime tropical (mT) __1__ continental arctic (cA) __3__ continental tropical (cT) __2__ continental polar (cP) 1. extremely cold and dry 2. cold and dry 3. hot and dry 4. cool and humid 5. warm and humid

From the list below, choose all that apply to a low pressure system in the Northern Hemisphere:

air rises air flows inward to the low air flows counterclockwise around a low known as a cyclone

From the list below, choose all that apply to a high pressure system in the Northern Hemisphere:

air sinks air flows clockwise around the high known as an anticyclone air rises air flows outward from the high air flows counterclockwise around a high air flows inward to the high

An extremely large body of air that has similar horizontal temperature and moisture characteristics at any given altitude is called

an air mass

What is the instrument used to measure astmospheric air pressure ?

barometer

Hurricanes and mid-latitude cyclones are similar in that

both are areas of low pressure

_____is an apparent force, resulting from the earth's rotation, that is responsible for the apparent deflection of the wind to right of its path in the Northern Hemisphere and to the left of its path in the Southern hemisphere.

coriolis effect

The development or strengthening of a mid-latitude cyclone is known as

cyclogenesis

Middle latitude cyclones are also called (check ALL that apply but NO incorrect answers):

depression extratropical cyclone low hurricane

The transition zone (or boundary) between two distinct air masses is called a

front

In the Northern Hemisphere, the polar jetstream is typically

further south and stronger in the winter

Very closely spaced isobars on a weather chart indicate

high winds

Relatively strong winds concentrated within a narrow band in the atmosphere are called

jet stream

Which air mass generally has warm temperatures and a high moisture content?

mT

From the list below, select the two air masses have the most influence on the weather in the midwestern United States? (must choose the correct 2 choices with no wrong answers for credit - this is an all or nothing question)

mT cT cP cA

Eddy motions created by obstructions such as buildings, hangars, etc. create ______turbulence.

mechanical

A cyclonic storm (a low) that most often forms along a front in the middle and high latitudes, outside of the tropics, is known as a wave cyclone or ________

middle latitude, midlatitude, mid-latitude, middle-latitude)cyclone.

What is considered standard sea-level atmospheric pressure in millibars(mb), inches of mercury("Hg), hectopascals (hPa),and pounds per square inch (psi)?

millibars 1013.35 inches of mercury 29.32

Which is a characteristic of the dissipating stage in an ordinary thunderstorm life cycle?

mostly downdrafts

The rate of decrease of air pressure per unit of horizontal difference is known as the ______.

pressure gradient

Four scales of wind circulations (microscale, mesoscale, synoptic scale, planetary scale) are ranked by their relative ______

size

Regions where air masses originate and acquire their properties of temperature and moisture characteristics are called

source regions

Which is a characteristic of the cumulus stage in an ordinary thunderstorm life cycle?

strong updrafts

What 3 ingredients are needed for a thunderstorm to develop and grow?

sufficient moisture, initial lifting mechanism, unstable air

Of the thunderstorm types listed below, choose the one that is usually the most severe and lasts the longest?

supercell

The boundary zone separating the northeast trade winds of the Northern Hemisphere from the southeast trade winds of the Southern Hemisphere is known as

the Intertropical Convergence Zone (ITCZ)

Which is a characteristic of the beginning of the mature stage in an ordinary thunderstorm life cycle?

the beginning of precipitation

A mid-latitude cyclone begins to gradually dissipate during the advanced occlusion because:

the energy supply of warm, moist air from the "warm sector" has been cut-off.. the low is now surrounded by cool/cold air

what is the meaning of the term "air pressure" as it relates to meteorology?

the force of the air above a given area or level.

Many, if not most, Atlantic hurricanes can be traced back to

tropical waves that form over Africa

In the United States, most thunderstorms occur in the southeast where the air is usually moist and unstable in the hot summertime.

true

A wind direction given as "270 degrees" means the wind is coming from the

west

A sudden change in direction and/or speed of the wind in a short distance is called ____

wind shear