THE CLIMATE OF THE BRITISH ISLES

The British Isles

The main influences on the climate of the British isles are its latitude and itsmaritime position.

It lies within the cool temperate western maritime (CTWM) climate belt.

It does not experience extremes of temperature and it receives precipitationthroughout the year.

One of the most striking features of the weather in the British Isles is itsunpredictability.

Cool wet winters

warm wet summers

Precipitation is experience throughout the year.

Cool Temperate Western Maritime Climate

Temperature of CTWM

In the summer mean temperature in the UK are lower than average for the latitude.

Although daily maximum temperature can reach 30oC, average monthlytemperatures seldom exceed 18oC. This is due to the cooling influence of the Atlanticocean.

In the winter mean temperatures are above freezing between 2oC and 7oC. In somecoastal areas, such as Cornwall and the western isles of Scotland, relatively highaverage winter temperatures of 6oC result from the warming influence of the sea.

The mean average temperature range within the CTWM is relatively small butincreases with distance from the west coast.

Cambridge in East Anglia has an annual temperature range of 14oC compared with10oC for Plymouth in Devon

Precipitation of CTWM

Precipitation is experience throughout the year but varies with relief.

In upland areas, in particular those close to western coast, rainfall totals canexceed 2,500 mm.

A short distance further east, on lowland in the shadow of the mountains,annual totals can be as little as 500mm.

Most of the rainfall is brought by frontal systems moving from west to east.

In general summer is the driest season, followed by the winter.

This is because high pressure weather systems are more likely to becomeestablished in these seasons and block the approaching fronts deflecting themto the north or south of the British Isles

Wind of CTWM

The prevailing wind direction is southwest and this is governed by the generalatmospheric circulation system.

However, although the British Isles receives most air streams from the west,easterly winds do occur. They generally bring spells of dry weather.

Know the characteristics of the climate and British air masses

Discuss the relative importance of the physical factors that influence the climate of Britain.

40 marks

Essay style question – make notes, plan and write.

Use the essay generic mark scheme on the P:drive