MEA 130 Exam 3 Questions with Correct Answers Latest Update 2025-2026
aerovane - Answers A device that resembles a wind vane with a propeller at one end. Used to indicate
wind speed and direction.
air pressure - Answers The force exerted by the weight of a column of air above a given point.
aneroid barometer - Answers An instrument for measuring air pressure; it consists of evacuated metal
chambers that are very sensitive to variations in air pressure.
anticyclone - Answers An area of high atmospheric pressure characterized by diverging and rotating
winds and subsiding air aloft.
anticyclonic flow - Answers Winds blow out and flow clockwise about an anticyclone (high) in the
Northern Hemisphere, and they blow out and flow counterclockwise about an anticyclone in the
Southern Hemisphere.
barograph - Answers A recording barometer.
barometric tendency - Answers The nature of change in atmospheric pressure over the past several
hours. It can be a useful aid in short-range weather prediction.
Buys Ballot's law - Answers The law that states that with your back to the wind in the Northern
Hemisphere, low pressure will be to your left and high pressure to your right. The reverse is true in the
Southern Hemisphere.
convergence - Answers The condition that exists when the wind distribution within a given region results
in a net horizontal inflow of air into the area. Because, at lower levels, it is associated with an upward
movement of air, areas of these types of winds are regions favorable to cloud formation and
precipitation.
Coriolis force - Answers The deflective effect of Earth's rotation on all free-moving objects, including the
atmosphere and oceans. Deflection is to the right in the Northern Hemisphere and to the left in the
Southern Hemisphere.
cup anemometer - Answers An instrument used to determine wind speed.
cyclone - Answers An area of low atmospheric pressure characterized by rotating and converging winds
and ascending air.
cyclonic flow - Answers Winds that blow in and counterclockwise about a cyclone (low) in the Northern
Hemisphere and in and clockwise about a cyclone in the Southern Hemisphere.
divergence - Answers The condition that exists when the distribution of winds within a given area results
in a net horizontal outflow of air from the region. At lower levels, the resulting deficit is compensated for
by a downward movement of air from the aloft; hence, areas of divergent winds are unfavorable to
cloud formation and precipitation.
, geostrophic wind - Answers A wind, usually above a height of 600 meters, that blows parallel to the
isobars.
high - Answers High barometric pressure.
isobar - Answers A line drawn on a map connecting points of equal barometric pressure, usually
corrected to sea level.
low - Answers Low barometric pressure.
mercury barometer - Answers A mercury-filled glass tube in which the height of the column of mercury
is a measure of air pressure.
millibar - Answers The standard unit of pressure measurement used by the National Weather Service.
One of these equals 100 newtons per square meter.
pressure gradient - Answers The amount of pressure change occurring over a given distance.
pressure tendency - Answers The nature of the change in atmospheric pressure over the past several
hours. It can be a useful air in short-range weather prediction.
prevailing wind - Answers A wind that consistently blows from one direction more than from any other.
standard atmosphere - Answers The idealized vertical distribution of atmospheric pressure (as well as
temperature and density), which is taken to represent average conditions in the real atmosphere.
wind - Answers Air flowing horizontally with respect to Earth's surface.
wind vane - Answers An instrument used to determine wind direction.
air mass - Answers A large body of air, usually 1600 kilometers or more across, that is characterized by
homogeneous physical properties at any given altitude.
air-mass weather - Answers The conditions experienced in an area as an air mass passes over it. Because
air masses are large and relatively homogeneous, air-mass weather will be fairly constant and may last
for several days.
arctic (A) air mass - Answers A bitterly cold air mass that forms over the frozen Arctic Ocean.
continental (c) air mass - Answers An air mass that forms over land; it is normally relatively dry.
lake-effect snow - Answers Snow showers associated with a cP air mass to which moisture and heat are
added from below as it traverses a large and relatively warm lake, rendering the air mass humid and
unstable.
maritime (m) air mass - Answers An air mass that originates over the ocean. These air masses are
relatively humid.
aerovane - Answers A device that resembles a wind vane with a propeller at one end. Used to indicate
wind speed and direction.
air pressure - Answers The force exerted by the weight of a column of air above a given point.
aneroid barometer - Answers An instrument for measuring air pressure; it consists of evacuated metal
chambers that are very sensitive to variations in air pressure.
anticyclone - Answers An area of high atmospheric pressure characterized by diverging and rotating
winds and subsiding air aloft.
anticyclonic flow - Answers Winds blow out and flow clockwise about an anticyclone (high) in the
Northern Hemisphere, and they blow out and flow counterclockwise about an anticyclone in the
Southern Hemisphere.
barograph - Answers A recording barometer.
barometric tendency - Answers The nature of change in atmospheric pressure over the past several
hours. It can be a useful aid in short-range weather prediction.
Buys Ballot's law - Answers The law that states that with your back to the wind in the Northern
Hemisphere, low pressure will be to your left and high pressure to your right. The reverse is true in the
Southern Hemisphere.
convergence - Answers The condition that exists when the wind distribution within a given region results
in a net horizontal inflow of air into the area. Because, at lower levels, it is associated with an upward
movement of air, areas of these types of winds are regions favorable to cloud formation and
precipitation.
Coriolis force - Answers The deflective effect of Earth's rotation on all free-moving objects, including the
atmosphere and oceans. Deflection is to the right in the Northern Hemisphere and to the left in the
Southern Hemisphere.
cup anemometer - Answers An instrument used to determine wind speed.
cyclone - Answers An area of low atmospheric pressure characterized by rotating and converging winds
and ascending air.
cyclonic flow - Answers Winds that blow in and counterclockwise about a cyclone (low) in the Northern
Hemisphere and in and clockwise about a cyclone in the Southern Hemisphere.
divergence - Answers The condition that exists when the distribution of winds within a given area results
in a net horizontal outflow of air from the region. At lower levels, the resulting deficit is compensated for
by a downward movement of air from the aloft; hence, areas of divergent winds are unfavorable to
cloud formation and precipitation.
, geostrophic wind - Answers A wind, usually above a height of 600 meters, that blows parallel to the
isobars.
high - Answers High barometric pressure.
isobar - Answers A line drawn on a map connecting points of equal barometric pressure, usually
corrected to sea level.
low - Answers Low barometric pressure.
mercury barometer - Answers A mercury-filled glass tube in which the height of the column of mercury
is a measure of air pressure.
millibar - Answers The standard unit of pressure measurement used by the National Weather Service.
One of these equals 100 newtons per square meter.
pressure gradient - Answers The amount of pressure change occurring over a given distance.
pressure tendency - Answers The nature of the change in atmospheric pressure over the past several
hours. It can be a useful air in short-range weather prediction.
prevailing wind - Answers A wind that consistently blows from one direction more than from any other.
standard atmosphere - Answers The idealized vertical distribution of atmospheric pressure (as well as
temperature and density), which is taken to represent average conditions in the real atmosphere.
wind - Answers Air flowing horizontally with respect to Earth's surface.
wind vane - Answers An instrument used to determine wind direction.
air mass - Answers A large body of air, usually 1600 kilometers or more across, that is characterized by
homogeneous physical properties at any given altitude.
air-mass weather - Answers The conditions experienced in an area as an air mass passes over it. Because
air masses are large and relatively homogeneous, air-mass weather will be fairly constant and may last
for several days.
arctic (A) air mass - Answers A bitterly cold air mass that forms over the frozen Arctic Ocean.
continental (c) air mass - Answers An air mass that forms over land; it is normally relatively dry.
lake-effect snow - Answers Snow showers associated with a cP air mass to which moisture and heat are
added from below as it traverses a large and relatively warm lake, rendering the air mass humid and
unstable.
maritime (m) air mass - Answers An air mass that originates over the ocean. These air masses are
relatively humid.
