Thursday 14 January 2010

Can winter anticyclonic conditions be an extreme weather example?




What are the weather conditions shown in this map?


Firstly there is an winter anticyclone. The pressure is over 1000 (high pressure) and winds are blowing in a clockwise direction. There is also quite a large gap between isobars showing winds aren't that high which fits in the model of a winter anticyclone. There will be hardly any clouds allowing the sun to shine through although the temperatures will still be low as there is a lack of clouds which allows heat to escape back into the atmosphere. We can see this through the symbols on the chart. The winter anticyclone has built up through cold and dry condition in Scandinavia and Eastern Europe. The Polar Continental air mass is the main one associated with this weather system.


There is also a cold front passing through North East England and Scotland. Traditionally, in anticyclonic conditions we do not see fronts forming but it just goes to show that real weather is much more complex than what the textbook says. In this front the cold air advances and force the warm air to rise sharply.

When the warm air rises quickly is condenses and causes a short rapid snap of heavy rain. Hence around the front we see symbols of rain.


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.


So what are the risks with this condition?
  1. Firstly, temperatures can become extremely low bringing many health risks like hypothermia especially to children and the elderly.
  2. Many who suffer with breathing difficulties will probably have many problems. This is because first off the air is cold and dry and secondly there is a high risk or fog which is known to making breathing difficulties bigger.
  3. Fog is difficult to forecast in these situations do to cloud cover or the lack of it! This makes forecasting difficult and when extreme anticyclonic conditions are arising it is hard to forecast hence hard to act appropriately.
  4. Some extreme situations see heavy snow of ice falling. As we have seen in the last too months this can cause severe disruption. Many lives are lost, over a million people are not able to reach work and livestock are dying as they are not able to cope with these cold conditions.

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