Air masses affecting the UK

An air mass is a large volume of air which travels from one area to another. An air mass is a large body of air - usually thousands of kilometres wide.

It will remain over a place for a period of time and will pick up the key temperature and moisture characteristics of that area.

It will then start to move bringing those characteristics with it.

Air masses never mix. Our weather is determined by which air mass is most dominant at that time. This is one of the reasons why our weather can be so different from one day to the next.

The weather an air mass brings is determined by the region it has come from and the type of surface it has moved over.

There are five main air masses which affect the UK as detailed by the map below.

Air masses affecting the UK

To understand the weather an air mass brings, it is important to remember three things:

  • Where has it come from?
  • Has it travelled over land or sea?
  • Is the air hot or cold?

Continental air masses travel over land so bring dry.

Maritime air masses travel over the sea which makes them wet. (Maritime is another word for sea.)

Polar air masses come from polar regions which makes them cold.

The Arctic air masses travels from the Arctic circle. This make the air mass cold.

Tropical air masses travel from closer to the Equator, from Northern Africa and the Mediterranean. This makes them hot.

Question

An air mass which moves over land from the Tropics is called _____ _____ and brings with it _____ _____ weather?

An air mass which moves over land from the Tropics. is called Tropical Continental and brings with it warm, dry weather.

Question

An air mass which comes from the Tropic of Cancer, over the Atlantic Ocean, is called _____ _____ and brings with it _____ ______ weather?

An air mass which comes from the Tropic of Cancer, over the Atlantic Ocean, is called Tropical Maritime and brings with it warm, wet weather.

Question

An air mass which comes from the north of the UK, in the ______, is called _____ _____ and brings with it _____ ______?

An air mass which comes from the north of the UK, in the Arctic, is called Arctic Maritime and brings with it heavy snow?