Which air masses affect the UK?
Quick version
Air masses are large volumes of air.
Five main air masses affect the UK
- Tropical Maritime (mT) - brings warm, wet weather from the Atlantic Ocean
- Tropical Continental (cT) - brings warm, dry weather from North Africa
- Polar Maritime (mP) - brings cold, wet weather from the North Atlantic
- Polar Continental (cP) - brings cold, dry weather from Siberia
- Arctic Maritime (mA) - brings very cold (sometimes wet) weather from the Arctic Ocean
Video - How do air masses affect the UK?
Watch this video to find out which air masses affect the UK, where they come from, and the weather they bring.
Find out more about how air masses affect UK weather
Learn in more depth
What is an air mass?
An air mass is a large volume 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.
The weather an air mass brings is determined by:
- the region it has come from, eg the Arctic Circle
- the type of surface it has moved over, eg over sea
How do air masses develop their characteristics?
To understand the weather an air mass brings, it is important to remember two things:
- What How far north or south somewhere is. Latitude is measured in degrees. The lowest latitude is on the Equator (0掳). High latitudes are at the North Pole (90掳 north) and South Pole (90掳 south) has it come from?
- What surface has it travelled over?
These two pieces of information will help you to:
- name the air mass
- describe its characteristics
The general features of different air masses are shown in the table below.
| Source latitude | Characteristics |
|---|---|
| Tropics | Warm |
| Arctic/Polar | Cold |
| Source surface | Characteristics |
|---|---|
| Land (Continental) | Dry |
| Oceans (Maritime) | Wet |
What are the five main UK air masses?
There are five main air masses which affect the UK, shown in the map below.
- Tropical Maritime
- Tropical Continental
- Polar Maritime
- Polar Continental
- Arctic Maritime
What are the weather characteristics of the five main UK air masses?
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.
| Name | Source area | Weather characteristics | Wind |
|---|---|---|---|
| Tropical Maritime (mT) | Atlantic Ocean | Warm and wet | Strong south-westerly |
| Tropical Continental (cT) | Southern Europe and North Africa | Warm and dry | Light breezes |
| Polar Maritime (mP) | North Atlantic | Cool and wet | Strong westerly/north-westerly |
| Polar Continental (cP) | Northern Central Europe and Siberia | Cold and dry | Little wind |
| Arctic Maritime (mA) | Arctic Ocean | Very cold. Not always wet due to low humidity. | Strong northerly |
Seasonal changes
The weather air masses bring changes depending on seasonal changes.
Temperatures in the summer months are always higher than in winter months.
- Tropical Maritime brings warm weather in summer, and mild weather in winter
- Polar Continental brings warm summers and cold winters
- Arctic Maritime does not occur very often, but can bring heavy snow in winter and (infrequently) light showers in summer.
- Tropical Continental can bring heatwaves and droughts, particularly in summer
Test what you have learned
Fill in the blanks to complete these sentences about air masses.
Question 1
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 2
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.
Quiz
Recap what you have learned
Air masses are large volumes of air that bring different weather conditions.
Tropical air masses from the tropics bring warmer weather
Arctic and polar air masses from the Arctic and poles bring colder weather
Continental air masses from over land bring drier weather
Maritime air masses from over the ocean bring wetter weather
Five main air masses affect the UK
- Tropical Maritime (mT) - brings warm, wet weather from the Atlantic Ocean
- Tropical Continental (cT) - brings warm, dry weather from North Africa
- Polar Maritime (mP) - brings cold, wet weather from the North Atlantic
- Polar Continental (cP) - brings cold, dry weather from Siberia
- Arctic Maritime (mA) - brings very cold (sometimes wet) weather from the Arctic Ocean
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