Science of the skies: Air masses

Discover the different air masses that affect the weather over the British Isles.

What are air masses and where do they come from

The weather over the British Isles comes from both the Ocean (maritime air masses) and from the continent (continental air masses).

An air mass is a body of air which is fairly uniform in temperature and humidity.

Air Masses by Met OfficeMet Office

Air Masses

There are six different air masses which affect the weather over the British Isles.

Tropical Maritime

The source of this air mass is Atlantic.

Warm, moist air brings cloud, rain and mild weather.

Polar Maritime

The source of this airmass is Greenland or Arctic Sea.

Wet, cold air brings cold showery weather.

Returning Polar Maritime

The source of this air mass is Greeland or Arctic and comes via North Atlantic.

Moist, mild and unstable air bringing cloud and rain showers.

Arctic Maritime

The source of this airmass is Arctic.

Wet, cold air brings snow in winter.

Polar low-pressure systems forming in this air mass can sometimes lead to widespread and heavy snowfall.

Polar Contintental

The source of this air mass is Central Europe.

Hot air brings dry summers.
Cold air brings snow in winter.

This air mass brought low temperatures and snowfall to many areas in February and March 2018 and got the phrase 'beast from the east'.

Tropical Continental

The source of this air mass is North Africa.

Hot, dry air brings hot weather in summer.

This air mass was responsible for bringing temperatures over 40 deg C to England for the first time on 19 July 2022.

Forecasting weather

Using these air masses you can roughly work out what the likely weather will be over British Isles. 

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