weather [appearing pictures with notes] [1]

• The Sun is the source of all forces that causes wind.
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• Energy from the Sun strikes Earth most directly at the Equator [an imaginary centre line].
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• However, Earth has a "tilt" which creates an unequal heating of the Earth’s surface
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• This means in some areas the same amount of energy is spread over a larger area.
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• This "heat" energy turns any water droplets in the air into clouds
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• These water droplets are so light that they rise on the warm air from below.
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• A cycle begins, hot air rises, cools and sinks, replacing the warm air at ground level.
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• As the hot air rises to create clouds, it creates a low pressure area below it.
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• As cold air falls, creating high pressure above. The descending air stops clouds forming.
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• It is these areas of high and low pressure which are so important for our weather........
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• ....high pressure areas rotate clockwise and low pressure areas rotate anticlockwise.
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• Rotation means to go around.
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• Rotation clockwise.
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• Rotation anticlockwise
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• A barometer measures air pressure and predicts the type of weather to expect.
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• Pressure is the physical force exerted on an object, in this case, air on the ground.
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• These are the types of weather you can expect with high and low pressure systems.
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• This is a map of two pressure systems, both high and low, either side of the UK.
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• These air pressure systems or air masses may cover huge areas as seen here.
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• So let's recap what we have covered so far............
  The Sun is the source of the energy that creates wind. Energy from the Sun is unevenly spread across the Earth. Energy in the form of heat causes water droplets in the air to form clouds. Warm clouds of air rise pulling in cooler surrounding air. This creates a cycle of rising warm air [low pressure] and falling cooler air [high pressure]. Low pressure rotates anticlockwise and high pressure rotates clockwise. A barometer measures air pressure and suggests the likely weather. Air pressure systems or air masses can be huge in size.

Read each of the labels in turn. As you hover over each of the labels a picture will appear to help you better understand what the label is saying and explaining what the words in bold mean.