Maritime polar air mass
Also called: mP · Topic: Air Masses, Fronts, Cyclones and Thunderstorms · NCERT: Class 11, Ch 9 "Atmospheric Circulation and Weather Systems"
Meaning
A maritime polar (mP) air mass is cool and moist. It forms over cold oceans in high latitudes, such as the North Pacific and the North Atlantic. The cold sea keeps the air cool, and water evaporating from the sea makes it moist. When mP air moves onto land, it brings cool, cloudy and showery weather, mostly to west coasts in the middle latitudes.
Example
mP air from the North Pacific often reaches the west coast of Canada, for example British Columbia. It brings grey skies and frequent showers there for much of the year.
Don't confuse with
- Continental polar (cP) air mass: cP air is also cold, but it forms over snow-covered land. So it is dry and stable, while mP air is moist.
Related concepts
- Air mass
- Source region
- Maritime tropical air mass
- Continental tropical air mass
- Continental polar air mass
- Continental arctic air mass