Air masses

An air mass is a large volume of air which travels from one area to another. 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

The following questions help to describe and explain the weather that brings air masses together.

  1. Where has the air mass come from - is it the Arctic Circle, the North Pole or the Tropics?
  2. Has the air mass passed over sea or land?

These two pieces of information will help you name the air mass and describe its characteristics. The basic ideas are shown in the table below.

Source areaCharacteristics
LandDry
OceansWet
TropicsWarm
ArcticCold

Weather characteristics

You should memorise the information in the table below to make sure that you can correctly identify the weather characteristics of air masses from each source area.

NameSource areaWeather characteristics
Tropical Maritime (mT)Atlantic OceanWarm and wet
Tropical Continental (cT)Southern Europe and North AfricaWarm and dry
Polar Maritime (mP)North AtlanticCold and wet
Polar Continental (cP)Northern EuropeCold and dry
Arctic Maritime (mA)Arctic OceanVery cold. Not always wet due to low humidity.

The temperature of an air mass is also determined by seasonal changes. Temperatures in the summer months are always higher than in winter months.

The air mass known as the Arctic Maritime does not occur very often, but when it does it brings with it heavy snow.

Questions

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.