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Arctic air is deeply cold, colder than polar air masses. Arctic air can be shallow in the summer, and rapidly modify as it moves equatorward. [8] Polar air masses develop over higher latitudes over the land or ocean, are very stable, and generally shallower than arctic air. Polar air over the ocean (maritime) loses its stability as it gains ...
A cold front is the leading edge of a cooler mass of air at ground level that replaces a warmer mass of air and lies within a pronounced surface trough of low pressure.It often forms behind an extratropical cyclone (to the west in the Northern Hemisphere, to the east in the Southern), at the leading edge of its cold air advection pattern—known as the cyclone's dry "conveyor belt" flow.
A cold-air pool is an accumulation of cold air in a topographic depression, such as a valley or basin. The cold air is produced by radiative cooling at night along the slopes and sinks down, as it is denser than the surrounding air, settling at the bottom of the depression.
At the 60th parallel, the air rises to the tropopause (about 8 km at this latitude) and moves poleward. As it does so, the upper-level air mass deviates toward the east. When the air reaches the polar areas, it has cooled by radiation to space and is considerably denser than the underlying air. It descends, creating a cold, dry high-pressure area.
On weather maps, the surface position of the cold front is marked by a blue line with triangles pointing in the direction where cold air travels and it is placed at the leading edge of the cooler air mass. [2] Cold fronts often bring rain, and sometimes heavy thunderstorms as well. Cold fronts can produce sharper and more intense changes in ...
Occluded fronts usually form around mature low pressure areas.There are two types of front occlusions, warm and cold, depending on the temperature contrast: . In a cold occlusion, the cold air mass that overtakes the warm air mass ahead is colder than the cool air at the very front and plows under both air masses, and often has the characteristics of a cold front.
Continental climates exist where cold air masses infiltrate during the winter from shorter days and warm air masses form in summer under conditions of high sun and longer days. Places with continental climates are as a rule either far from any moderating effect of oceans or are so situated that prevailing winds tend to head offshore. [6]
Horizontal deformation in mid-latitude cyclones concentrates temperature gradients—cold air from the poles and warm air from the equator.. Horizontal shear has two effects on an air parcel; it tends to rotate the parcel (think of placing a wheel at a point in space and as the wind blows, the wheel rotates) and deform the parcel through stretching and shrinking.