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