Look at a weather map taken from your local newspaper. You will find a map of your country on which a number of lines are super-imposed. The lines are called isobars . The air pressure at every point on a given isobar is the same.

The L s and the H s stand for low and high pressure systems respectively.

• What sort of weather do you associate with each of these?

• Discuss the various symbols which appear on the above map.

• How would this hurricane appear on the weather map? Would it appear as an H or an L? What would you expect of the surrounding isobars?

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Weather maps



A high pressure zone is associated with fine weather.

A low pressure zone signifies stormy weather.|





A hurricane or cyclone is signified by a low pressure zone of a particular type. In this case, the L zone appears to be relatively small, and the isobars are wrapped tightly around it. This shows that there are great differences in the air pressure, resulting in very strong winds.