To what extent is the climate of the British Isles a product of the air masses that affect it? 40 marks
Climate is defined as the weather averaged over a 30 year period, with weather being determined by temperature, humidity, wind and precipitation. The climate in the British Isles is described as cool temperate western maritime climate, although there are regional differences in climate across the British Isles; with average temperatures ranging from -0.2 to 20.9 degrees Celsius. The climate of the British Isles is influenced by the movement of five major air masses. However, it is also influenced by other factors, including its topography, ocean currents, latitude, and weather systems. Firstly, it can be argued that air masses play a large part in the overall climate of the British Isles. Air masses are large bodies of air with reasonably uniform temperature, pressure and humidity throughout. There are five main air masses that influence the climate: tropical maritime(TM), polar maritime (PM), tropical continental (TC), polar continental (PC) and arctic maritime (AM). The direction of the air masses can be seen in the diagram below. Tropical Maritime brings warm moist air from the Atlantic Ocean. This warm air hits areas of high relief in western England and Wales, causing the air to rise, which means clouds form. Areas of high relief in the west of England include Dartmoor and Exmoor. The air is very moist as it is from the ocean, so there is lots of precipitation. This wind is warm, which means that is has a warming affect in the winter, however in the Summer because the land has a lower specific heat capacity, it heats up more than the Atlantic ocean. Therefore it has a cooling affect in summer. Tropical Continental air masses bring hot and dry air in summer. This causes high temperatures with very little precipitation, and is the reason for heat waves in the British Isles. For example the heat wave in July 2013, where temperatures reached 33.5°C . Polar...
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