1. 1 Frontal weather systems.

2. 2 Relief Rainfall. Wind direction. Cooler air. Warmer air.

3. 3 Convectional Rainfall Cooler air. Ground warms up and, in turn, warms air. Warm air rises, taking water vapour with it.

4. 4 Frontal Rainfall Cold Air Mass Cold Front Warm Air Mass

5. 5 Frontal Rainfall. Triangles, sometimes coloured blue = a cold front. Semi-circles, sometimes coloured red = a warm front. A mix of symbols, = an occluded front. This is when a cold front pushes under a warm front. More on this later.

6. 6 Fronts from the Atlantic pass over the UK every few days. Britain's weather is dominated by the passing of these depressions. These form when warm, moist air meets colder, drier air. They are areas of low pressure which bring cloud, rain and wind to the British Isles.

7. 7 Weather fronts change weather...

8. 8 As fronts from the Atlantic pass over us the weather changes.

9. 9 So, as fronts pass over the UK they change the weather as they go. Using what you know describe the changes in temperature and rainfall for the South-eastern corner of the UK as the frontal systems pass over. Now in your books copy the notes on the next slide.

10. 10 Characteristics of a typical Western Maritime Temperate Climate (Case study - the UK) Prevailing winds are from the west or south-west. Mixing of warm equatorial air masses and cold polar air masses create areas of turbulence. These can be seen as swirling masses of cloud on satellite photos. Each one represents a low pressure system with fronts and they tend to move from west to east. Successions of low pressure systems and their fronts bring ‘pulses’ of rainfall for much of the year. Rainfall is fairly constant all year around Temperatures are stabilised by the large areas of ocean. In Western Europe the North Atlantic Drift ocean current (Gulf Stream) keeps temperatures higher than would be expected.