CHAPTER 8- Air mass Flashcards
What is a Canadian Air Mass?
South bound frigid air mass that clashes with north bound tropical air from Gulf of Mexico. As it advances, it modifies and becomes warmer.
What is an air mass?
A large body of air usually 1600KM or more across, that is characterized by homogenous physical properties at any given altitude. It modifies the area it covers with its temperature and moisture.
What is a source region?
Areas where air masses originate. They need an extensive and uniform area and an an of general stagnation or low atmospheric circulation.
The air mass type most likely to form thunderstorms is?
mT
An air mass from the Gulf of Mexico that moves northward over the U.S. In winter would be labeled
mT
An ideal source region of air masses should be
Physically uniform and have general stagnation of atmospheric circulation.
The cP air-mass in North America originates in
Interior Alaska and Canada
Most of the precipitation for the region east of the Rocky Mountains comes from
mT air masses
When an area is experiencing several consecutive days of rather constant weather, it is experiencing
Air-mass weather
Characteristics of an air mass source region include
Uniformity of temperature and moisture
In North America, the only air mass that forms only in the summer is
cT
The air masses that have the greatest influence on weather conditions in the Midwestern US are
cP and mT
An mP air mass is
Humid and cold
An air mass is often modified as it moves over the Earth’s surface. This modifications is largely due to
Contact with the ground below
The coldest and driest winter air-mass in North America is the
cA
Why are the cT air masses of minor importance for the US?
No large source region is near the U.S.
Why are maritime air masses from the North Atlantic of only limited concern for weather in the U.S.?
Prevailing winds move them away from the U.S.
A cT air mass is
Warm and dry
Lake-effect snow is associated with which type of air mass?
cP
The air mass that provides much of the moisture for precipitation in the central and eastern United States
mT
This air mass may produce an occasional northeaster in the winter
mP
Which of these is not a process by which air masses are modified?
Calm winds. Processes that contribute to air modification is cooling from below, heating from below, evaporation of water, and limiting over mountains.
An air mass is a body of air with
Similar values of temperature and moisture in the horizontal
