Explain the Formation of Low Pressure Systems in an Area You Have Studied.

Essay 12th November 2011

Explain the formation of low pressure systems in an area you have studied.

Tropical cyclones are intense low pressure systems. They are very violent storms which can affect the whole world. There are a number of requirements needed for these devastating disasters to happen, but if they do manage to hit land, its impacts can be very dangerous.

Tropical cyclones, otherwise known as hurricanes, typhoons or willy-willies depending on where they are found around the globe can effect very large areas of the globe. Cyclones can eventually be very deadly; they are unpredictable, fast forming, very large in size with a diameter up to 800km and have enough energy within them, to supply the whole USA with electricity for six months. However, hurricanes do not form easily, there are seven conditions needed, for a severe low pressure system to form. Firstly, warm tropical oceans are needed with a sea temperature of at least 26°C, with a significant amount of water during autumn when sea temperatures are at their peak. Next, a disturbance is needed in the lower atmosphere circulation. Thirdly, a coriolis force created from the earth’s rotation needs to be large enough for it to affect the currently developing low pressure system. Then we need at all levels in the atmosphere which are mainly flowing in the same direction. The low pressure system is then required to have the rapid outflow of air in the troposphere replaced by inflow at ground level. Finally, we need unstable air, with high humidity, and excess heat being transported away from the storm by upper air winds.

These low pressure systems usually form in the westward flowing air to the north and south of the equator, known as the easterly wave. They begin as small scale tropical disturbances or tropical depressions, which cause warm air to rise, these may also develop into tropical storms with wind speeds up to 73 miles per hour. Once the rising air is established it...