1. THE CLIMATE OF THE BRITISH ISLES

4. The British Isles
The main influences on the climate of the British isles are its latitude and its
maritime position.
It lies within the cool temperate western maritime (CTWM) climate belt.
It does not experience extremes of temperature and it receives precipitation
throughout the year.
One of the most striking features of the weather in the British Isles is its
unpredictability.

5. Cool Temperate Western Maritime Climate
Cool wet winters
warm wet summers
Precipitation is experience throughout the year.

6. 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 monthly
temperatures seldom exceed 18oC. This is due to the cooling influence of the Atlantic
ocean.
In the winter mean temperatures are above freezing between 2oC and 7oC. In some
coastal areas, such as Cornwall and the western isles of Scotland, relatively high
average winter temperatures of 6oC result from the warming influence of the sea.
The mean average temperature range within the CTWM is relatively small but
increases with distance from the west coast.
Cambridge in East Anglia has an annual temperature range of 14oC compared with
10oC for Plymouth in Devon

7. 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 can
exceed 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 become
established in these seasons and block the approaching fronts deflecting them
to the north or south of the British Isles

12. Wind of CTWM
The prevailing wind direction is southwest and this is governed by the general
atmospheric 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.

16. 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
Use the essay generic mark scheme on the P:drive
Essay style question – make notes, plan and write.