In the next Step you’ll be able to consolidate what you’ve learnt so far by reading a weather map. Let’s first summarise what has been covered.
- Weather systems act to even out the pole to equator temperature gradient.
- Winds are trying to even out the pressure gradient.
- The wind blows around the depression in an anticlockwise direction in the Northern Hemisphere, following the pressure contours.
- The three dimensional processes are key – they lead to cloud, rain and energy being released.
The damage caused by a depression is governed by:
- The pressure difference, which in turn determines the wind speed.
- The time of the year, if the trees are in leaf, they offer more resistance to the wind and are more likely to be blown over.
- The preceding weather – if the ground is already waterlogged, flooding is much more likely. Also, trees and walls are more likely to collapse if on waterlogged ground.
- The path of the storm, and whether it passes over land or sea, or highly populated or less developed areas.
- The state of the tide – coastal flooding is much more likely if a storm coincides with a particularly high tide.
- Forecast accuracy – if people have notice to avoid travelling, keep high sided vehicles off roads etc. then the damage and disruption can be reduced.
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