Air Masses

An air mass is a large volume of air in the atmosphere that is mostly uniform in temperature and moisture

They can be classified by their latitude e.g. Polar (P) or Tropical (T) and the surface they develop over e.g. Maritime (m) or continental (c).

The latitude determines the temperature of the air and the surface affects the humidity and the moisture

Continental = Over sea

Maritime = Over land

Polar = North

Tropical = South

There are five main air masses which affect the British Isles:

Polar Maritime (Pm)

It is a very common air mass over Britain

It gives cool conditions throughout the year

Warms slightly as it crosses the Atlantic to become unstable in its lower layers

Gives heavy showers as it crosses highlands

It is a very common air mass over Britain

It gives cool conditions throughout the year

Warms slightly as it crosses the Atlantic Ocean to become unstable in its lower layers.

This can often give heavy showers as it crosses highlands, separated by bright intervals

It is associated with cumuloform clouds

Gives good visibility

Often strong winds and gales occur…