: an extensive region of the earth’s surface where large masses of air having uniform temperature and humidity conditions characteristic of the region originate.
What is a source region?
Parts of the Earth’s surface where the air can stagnate and gradually gain properties of the underlying surface are called source regions. The main source regions are the high pressure belts in the subtropics (giving rise to tropical air masses) and around the poles (the source for polar air masses).
What makes a good source region?
Source Regions A source region must have certain temperature and humidity properties that can remain fixed for a substantial length of time to affect air masses above it. Air mass source regions occur only in the high or low latitudes; middle latitudes are too variable.
What is the source region of cP?
Continental polar (cP) or continental arctic (cA) air masses are cold, dry, and stable. These air masses originate over northern Canada and Alaska as a result of radiational cooling. They move southward, east of Rockies into the Plains, then eastward.What is the source region of maritime tropical?
Maritime tropical air masses originate over the warm waters of the tropics and Gulf of Mexico, where heat and moisture are transferred to the overlying air from the waters below. The northward movement of tropical air masses transports warm moist air into the United States, increasing the potential for precipitation.
What are the source regions for each of the five air masses?
Air masses are commonly classified according to four basic source regions with respect to latitude. These are Polar (cold), Arctic (very cold), Equatorial (warm and very moist), and Tropical (warm).
What is the source of cold air?
Air plunging from Polar (Arctic) origins This air usually originates from northern Canada and often contains air from north of the Arctic Circle. Sometimes air from the North Pacific may settle over northern Canada and transform by means of extended darkness into a polar air mass.
Which area is a source region for mT air masses?
21. Off the southwestern coast of the United States and Mexico is a large maritime tropical (mT) air mass source region. Air masses generated in this area often bring heavy downpours of rain to the southwestern United States.What is the source region for a mP air mass?
MARITIME POLAR AIR MASS. The source region for mP air is over cold ocean currents or high latitude ocean waters. This air does not have as much moisture content as mT air. Since mP air is always near saturation, orographic lifting of the air mass can produce widespread rain or snow.
How does a source region influence an air mass?Where an air mass receives it’s characteristics of temperature and humidity is called the source region. Air masses are slowly pushed along by high-level winds, when an air mass moves over a new region, it shares its temperature and humidity with that region.
Article first time published onHow will you identify an ideal source area?
An ideal source region must meet two criteria. First, it must be an extensive and physically uniform area. The second criterion is that the area is characterized by a general stagnation of atmospheric circulation so that air will stay over the region long enough to come to some measure of equilibrium with the surface.
What are the characteristics of a good air mass source region?
If an area is described as a “good air mass source region,” what information can you give about it? That the area is long, flat, and uniform for air masses to originate and retain similar properties with the surface below it, such as arctic plains and warm oceans. You just studied 18 terms!
What is the best source region for an air mass quizlet?
A good source region for an air mass would be: generally flat areas of uniform composition with light surface winds. The origin of cP and cA air masses that enter the United States is: Northern Canada and Alaska.
Why is the United States not a good source region?
The central United States is not a good air-mass source region because it is located in the middle latitudes where westerly winds constantly stir the air. Such mixing of air causes constant fluctuation of temperature and pressure.
What is tropical maritime air?
Tropical maritime air is warm and moist in its lowest layers and, although unstable over its source region, during its passage over cooler waters becomes stable and the air becomes saturated.
Where does warm air come from?
The warm air rises as these air masses come together. Occluded fronts usually form around areas of low atmospheric pressure. There is often precipitation along an occluded front from cumulonimbus or nimbostratus clouds. Wind changes direction as the front passes and the temperature either warms or cools.
What is the zone between two air masses with different temperatures called?
front, in meteorology, interface or transition zone between two air masses of different density and temperature; the sporadic flareups of weather along this zone, with occasional thunderstorms and electrical activity, was, to the Norwegian meteorologists who gave it its name during World War I, analogous to the …
What is continental air mass?
continental air mass, vast body of air that forms over the interior of a continent, excluding mountainous areas. See air mass.
What is the main source region of cT air in North America?
Continental Tropical (cT) Air Their air is carried from Mexico and the southwestern U.S., and only impacts U.S. weather during the summertime. While cT air is unstable, it tends to remain cloudless due to its extremely low humidity content.
What are the 6 types of air masses?
This gives us six total types of air masses on Earth: maritime arctic (mA), maritime polar (mP), maritime tropical (mT); and continental arctic (cA), continental polar (cP) and continental tropical (cT).
What are the 4 types of air masses?
There are four categories for air masses: arctic, tropical, polar and equatorial. Arctic air masses form in the Arctic region and are very cold. Tropical air masses form in low-latitude areas and are moderately warm. Polar air masses take shape in high-latitude regions and are cold.
Where does rain occur in a warm front?
Rain occurs on the leading edge of a warm front. Since warm air is less dense than cold air, it gradually advances over the cold air in a process called gradual frontal lifting and allows for precipitation to develop ahead of the frontal boundary.
Where are the primary air mass source regions in North America?
In the north are found the Arctic air mass, over Greenland and the Canadian Arctic Archipelago; the polar continental, over northern central Canada; the maritime polar Pacific, over the Gulf of Alaska and the northern Pacific shores; and the maritime polar Atlantic, off the Atlantic provinces of Canada and New England.
What governs the temperature and humidity of an air mass?
Fronts govern the temperature and humidity of an air mass. 6.
What happens to an air mass as it moves away from its source region?
Air masses modify once they move out of their source region. … As a cold air mass builds, the temperature gradient between the cold air mass and the warmer air outside the air mass will increase. This in turn, increases the upper level winds which in turn helps steer an air mass away from its source region.
What is the difference between weather and climate?
Weather refers to short term atmospheric conditions while climate is the weather of a specific region averaged over a long period of time. Climate change refers to long-term changes.
What is the difference between a warm air and a cold air?
Cold air is more dense than warm air causing what is called high pressure. Warm air which is lighter cause low pressure. In the area of higher pressure the air molecules are closer together than they are in an area of lower pressure. … Cold air is denser and heavier and pushes the warmer, lighter air upward.
What is air masses and fronts?
An air mass is a body of air with a relatively constant temperature and moisture content over a significant altitude. Air masses typically cover hundreds, thousands, or millions of square kilometers. A front is the boundary at which two air masses of different temperature and moisture content meet.
What are conditions like after a warm air mass passes over a region?
The air mass behind a warm front is likely to be warmer and more moist than the one before the front. If a warm front is approaching, light rain or light winter precipitation is possible before and as the front passes. Behind the front, expect clearing skies, warmer temperatures and higher relative humdities.
Which location is only a significant source region during the summer?
Continental Tropical—Summer The only source regions for continental tropical air in North America are Mexico and the Southwestern United States. This air mass is hot, dry, and unstable, and causes droughts and heat waves when it persists for any length of time.
Which is colder polar or arctic?
Arctic air tends to be colder than polar air. In the air mass source regions, the temperatures of arctic air can reach far below 0 F, such as in the -30’s to -40’s below zero. Polar air tends to not start out as cold as this.
