Describe how the depression shown on this chart might produce extreme weather hazards.
What is an extreme weather event?
It is severe or unusual weather conditions e.g. hurricanes which cause severe impacts on the environment, people and economy.
What are the weather conditions shown in this map?
Firstly there is a depression. The pressure is below 1000mb (low pressure) and winds are blowing in an anti-clockwise direction. There is also quite a small gap between isobars showing winds are strong which fits in the model of a depression. There will be a large cloud cover as a depression is when warm air meets could air and this causes the warm air to cool resulting in precipitation. The depression has built up through cold and wet conditions in the Arctic Ocean. The Polar Maritime air mass is the main one associated with this weather system.
There is also a cold front passing through South East of England. Traditionally, in low pressure conditions we see occluded fronts forming on the actual land but even if it is close there will still be torrential rain on land. In this front the cold air advances and force the warm air to rise sharply. The result of a cold front is a rapid period of torrential rain.
So what are the risks with this condition?
- Firstly, temperatures can become extremely low bringing many health risks like hypothermia especially to children and the elderly.
- Torrential rainfall can lead to river flooding which especially with cold fronts lead to flash floods. The can cause many adverse effects for example the Boscastle 2004 flash floods caused injuries, £2 million damage to buildings and roads and coastal pollution as debris and fuel from cars flowed out into the sea.
- In extreme situations could lead to a snowstorm or blizzard which as we saw in February 2009 causes disruptions and deaths.
- It could lead to high waves and surge may be destructive to the coast.
- In the case of flooding if sewage systems failed then they would be a risk of cholera and other disasters.