What is extreme weather?
Usually severe and often unexpected, Extreme weather can bring choas and misery. Flood, droughts, heat waves and forest fires are examples of hazards caused by extreme weather. Too much or too little perciptiation, temperatures which are higher or lower than normal, extreme winds and intense low or high pressure systems create hazards which affect people all over the world.
Anticyclones are high pressure systems which bring periods of dry weather, light winds and clears skies.
The anticyclone in the summer brings cloudless skies meaning that the sun's energy reaches the earths surface, raising ground temperatures dramatically. If the anticyclone remains stationairy, it produces a heat wave like the one in europe 2003.
In winter the anticyclones bring different weather, the cloudless skies allows heat to escape into the atmoshpere, cooling the ground rapidly at night and leading to the formation of frost. Water vapour condenses into droplets, causing fog which can linger into the day until the heat of the sun evaporates it.
Depressions form over the Atlantic ocean when warm air from the tropics meets cold air from polar regions. Most of the UK's rainfall and dramatic storms are the result of depressions.
An Air mass forms when air is stationairy for several days. The air assumes the temperature and humidity of the area where it originated.