Where is maritime polar air found

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Arctic air masses move about as a shallow area of high pressure , commonly known as an "Arctic High". Northerly winds associated with a cyclone and trailing anticyclone, the center of the arctic air mass , transport the colder air southward.

Since the terrain is generally flat and free of any significant topographical features, arctic air masses entering the United States and can easily slide all the way to Texas and Florida.

These usually originate north of the Arctic Circle, where days of 24 hour darkness allow the air to cool to sometimes record-breaking low temperatures. Such air masses often plunge southward across Canada and the USA during winter, but very rarely form during the summer because the sun warms the Arctic. Continental polar cP : Cold and dry, but not as cold as Arctic air masses.

These usually form farther to the south and often dominate the weather picture across the USA during winter. Continental polar masses do form during the summer, but usually influence only the northern USA. These air masses are the ones responsible for bringing clear and pleasant weather during the summer to the North. Maritime polar mP : Cool and moist. They usually bring cloudy, damp weather to the USA.

The latter air mass generally is colder and drier than the mP off of the Pacific. Some maritime tropical air masses originate in the subtropical Pacific Ocean, where it is warm and air must travel a long distance over water. These rarely extend north or east of southern California. Some maritime tropical air masses originate over the Gulf of Mexico and Caribbean Sea. They can be associated with fog and low clouds as they moves northward. In the spring and summer, this air mass accounts for the thunderstorms in the Great Plains and elsewhere.

Continental tropical air masses originate in northern Mexico. They are characterized by clear skies and negligible rainfall. If one moves into the Great Plains and stagnates, a severe drought can result.

Topography can play a crucial role in the modification of air masses.