5.1.8

Frontal Precipitation

Test yourself

Frontal Precipitation

Air can rise in one of three main ways: convection precipitation, frontal precipitation, relief or orographic precipitation.

Illustrative background for Ocean air masses Illustrative background for Ocean air masses  ?? "content

Ocean air masses

  • If a large area (i.e. an area of many hundreds or thousands of square kilometres) remains above a uniform land or sea surface for a sufficiently long time, it will acquire the temperature and moisture of that area.
Illustrative background for Air masses Illustrative background for Air masses  ?? "content

Air masses

  • An air mass will be cold or warm, humid or dry depending on its origin and its path.
  • The British Isles are located where six main air masses meet.
Illustrative background for Air masses in Britain Illustrative background for Air masses in Britain  ?? "content

Air masses in Britain

  • The five main air masses affecting the British Isles are:

    • Tropical continental
    • Tropical maritime
    • Polar continental
    • Polar maritime
    • Arctic maritime
  • The sixth one is Returning Polar maritime

Illustrative background for Air frontsIllustrative background for Air fronts ?? "content

Air fronts

  • When two air masses meet, (e.g. a cold polar air mass meets a warm tropical air mass) the boundary is a front and the air does not mix immediately.
  • There are three types of front:
    • Warm fronts
    • Cold fronts
    • Occluded fronts.
Illustrative background for Air fronts cont.Illustrative background for Air fronts cont. ?? "content

Air fronts cont.

  • At a front, the colder air is heavier than the warmer air.
  • The lighter warmer air will rise above the other colder air.
  • The lighter warmer air expands and cools as it rises.
  • Cooler air cannot hold as much water vapour as a gas as warmer air.
Illustrative background for Water vapourIllustrative background for Water vapour ?? "content

Water vapour

  • The air becomes saturated with gaseous water vapour.
  • The gaseous water vapour condenses to liquid water droplets.
  • Eventually the weight of the liquid water droplets or ice is enough for gravity to return these water droplets / ice to the surface as precipitation.
Illustrative background for Depressions Illustrative background for Depressions  ?? "content

Depressions

  • Depressions form along a front between two air masses.
  • They affect the UK. They form in the Atlantic at the boundary of colder polar air and warmer tropical air.
  • They move across the UK from west to east.
  • In a depression, the air between the warm and cold fronts (the warm sector) is forced to rise, and it expands and cools and precipitation occurs.

Jump to other topics

1Geography Skills

2Geology of the UK

3Geography of the World

4Development

5Weather & Climate

6The World of Work

7Natural Resources

8Rivers

9Coasts

10Glaciers

11Tectonics

12Climate Change

13Global Population & Inequality

14Urbanisation

15Ecosystems

16Life in an Emerging Country

17Analysis of Africa

18Analysis of India

19Analysis of the Middle East

20Analysis of Bangladesh

21Analysis of Russia

Go student ad image

Unlock your full potential with GoStudent tutoring

  • Affordable 1:1 tutoring from the comfort of your home

  • Tutors are matched to your specific learning needs

  • 30+ school subjects covered

Book a free trial lesson