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Weather in the UK Image courtesy of NERC Satellite Receiving Station, Dundee University, Scotland These icons indicate that teacher’s notes or useful web.

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Presentation on theme: "Weather in the UK Image courtesy of NERC Satellite Receiving Station, Dundee University, Scotland These icons indicate that teacher’s notes or useful web."— Presentation transcript:

1 Weather in the UK Image courtesy of NERC Satellite Receiving Station, Dundee University, Scotland These icons indicate that teacher’s notes or useful web addresses are available in the Notes Page. This icon indicates the slide contains activities created in Flash. These activities are not editable. For more detailed instructions, see the Getting Started presentation. 1 of 30 © Boardworks Ltd 2005

2 The British Climate The British Isles has a temperate climate.
This means that it is not too hot, not too cold, not too dry and not too wet!

3 Learning objectives Why is the South of Britain warmer than the North?
Why are temperatures in January warmer on the West coast? Why is there more rainfall in the West? What is high and low pressure? Why is the weather in the UK so changeable? Learning objectives

4 July temperatures Isotherms are lines joining areas of equal temperature. ‘Iso’ means ‘the same’.

5 July temperatures What is the temperature at A?
16ºC, 15ºC, between 15ºC and 16ºC 2) What is the temperature at B? B 3) Which area is the hottest? Look at your atlas and name this area. A 4) Which of the following statements is true? a) The North is warmer than the South. b) The East is warmer than the West. c) The South is warmer than the North. Answers: 16ºC Between 14ºC and 15ºC. London conurbation The South is warmer than the North.

6 Why is the South of Britain warmer than the North?
Therefore, the sun’s rays are more concentrated in the South rather than the North of Britain.

7 Learning objectives Why is the South of Britain warmer than the North?
Why are temperatures in January warmer on the West coast? Why is there more rainfall in the West? What is high and low pressure? Why is the weather in the UK so changeable? Learning objectives

8 January temperatures Match the letter with the correct temperature. A
between 5ºC and 6ºC B 4ºC C between 4ºC and 5ºC Why is B colder than C, even though B is further south?

9 Why is it warmer in the West in January?
The North Atlantic Drift is a warm ocean current that brings higher temperatures to the west of the UK. The North Atlantic Drift starts its journey in the Gulf of Mexico.

10 Learning objectives Why is the South of Britain warmer than the North?
Why are temperatures in January warmer on the West coast? Why is there more rainfall in the West? What is high and low pressure? Why is the weather in the UK so changeable? Learning objectives

11 Rainfall in the British Isles
Describe the pattern of rainfall in the UK. Why is there more rainfall in the West of the British Isles?

12 Why is there more rainfall in the West?
Many of the mountain ranges in the British Isles occur in the West. The West is therefore more likely to experience relief rainfall. Relief rainfall is explained in the presentation ‘Weather – an introduction’.

13 Why is there more rainfall in the West?
The prevailing wind comes from the SW. This wind blows over the Atlantic, bringing moisture-laden air. The prevailing wind is the most common direction of wind.

14 Can you explain? This is a wet day in February. Explain the following…
1) why C is warmer than B. 2) why it is raining at D. 3) why A is colder than B.

15 Learning objectives Why is the South of Britain warmer than the North?
Why are temperatures in January warmer on the West coast? Why is there more rainfall in the West? What is high and low pressure? Why is the weather in the UK so changeable? Learning objectives

16 Getting practical Students may respond with ‘hot water rises’ and ‘cold water sinks’ – or even start to discuss simple convection currents. Explain why warm water/ warm air rises. It would be also good to use as a starter to air masses/ what happens when a warm air mass meets a cold air mass

17 Low pressure systems When air rises, it creates a low pressure system.
Air rising means clouds form and there is a possibility of rain.

18 High pressure systems When air sinks and warms this causes a high pressure system. There are clear skies and no rain. In Summer, clear skies mean that there are no clouds to stop the sun shining through and so days can be warm. Cloud free Europe At night, however, there are no clouds to stop the heat escaping so nights can be cool.

19 High pressure systems Image courtesy of NERC Satellite Receiving Station, Dundee University, Scotland In Winter, high pressure systems give rise to clear, bright days. However, clear skies also mean that there are no clouds to stop the heat escaping and so ice and frost can form.

20 Learning objectives Why is the South of Britain warmer than the North?
Why are temperatures in January warmer on the West coast? Why is there more rainfall in the West? What is high and low pressure? Why is the weather in the UK so changeable? Learning objectives

21 In the British Isles it can be sunny one minute and raining the next!
Why does the British Isles have unpredictable weather? In the British Isles it can be sunny one minute and raining the next! Why is this?

22 The answer has a lot to do with air masses…
Why does the British Isles have unpredictable weather? The answer has a lot to do with air masses… Air masses are huge blocks of air. They can be damp or dry, warm or cold, depending on where they came from and over what type of surface they have travelled. For example, an air mass that has travelled over the sea will increase its moisture content and be more likely to produce rainy weather. In essence, an air mass that travels over the sea will increase its moisture content, particularly in its lower layers. An air mass with a long land track will remain dry. A cold air mass flowing away from its source region over a warmer surface will be warmed from below making the air more unstable in the lowest layers. A warm air mass moving over a cooler surface is cooled from below and becomes stable in the lowest layers.

23 Air masses affecting the British Isles
Many air masses cross the British Isles, which explains our changeable weather!

24 What happens to the weather when the air masses meet?
Depressions (low pressure system) form when a cold air mass meets a warm air mass. The junction between these two different air masses is called a front. A front is associated with a change in the weather.

25 What happens at fronts? A warm front means that warm air is coming.
At a warm front, warm air is rising over cold air. This usually produces clouds and rain. A cold front means that cold air is coming. At a cold front, cold air pushes under the warm air. This produces strong winds and heavy rain.

26 Passage of a depression
Please Note These animations and exercises would also be suitable for use at KS4 and KS5.

27 Formation of a depression
Click on the red labels find out more! Please Note These animations and exercises would also be suitable for use at KS4 and KS5.

28 Depressions Please Note
These animations and exercises would also be suitable for use at KS4 and KS5.

29 Depressions – the changing weather!
These labels can be dropped above the orange line.

30 Weather definitions


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