The Great Storm of 1987
The British Isles weather patterns
Air masses and the British weather.
The five major air masses which affect the British Isles (Arctic maritime, Polar continental, Tropical continental, Tropical maritime and Polar maritime) are which contribute to the weather in the UK. When the air masses mover from their source region they change and are modified from the surface over which they travel, this alters there temperature, humidity and stability. For example, tropical air moving northward is cooled and becomes more stable, while polar air moving south become warmer and increasingly unstable. Each air mass brings its own characteristic weather conditions to the British Isles. When two air masses meet, they do not mix readily, due to differences in temperature and density. The point at which they meet is called a front. There are two different fronts: warm and cold front. Warm fronts are found where warm air is advancing and is forced to override cold air. A cold front occurs when advancing cold air undercuts a body of warm air. The warm air is forced to raise, cool and condense producing rain clouds. The clouds are often followed by precipitation. This is a weather system known as a depression. A depression is what occurred over the south west of England during October 1987. Depression is an area of low pressure. It causes unsettled weather, most famously clouds and precipitation. This is due to the centre of the depression air on the ground is converging and rising, producing clouds and rainfall. Each year about fifty depressions of varying sizes, pass over or close to the UK, brining cold rain, snow or strong winds. The depression the UK witnesses are responsible for the characteristics of the UK weather. Depressions can be devastating but are usually short lived, the great storm only lasted one night and caused so much damage. Depressions however, consist of four different stages; the early stage, open...
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