Location,+Characteristics+and+Structure+of+hurricanes

__Hurricane Location __ There are many different names for hurricanes depending on where they are situated (typhoons, cyclones). Hurricanes occur in the tropics, a region 23.5 degrees north and south of the equator (tropic of Cancer and Capricorn). In this region the temperature does not vary greatly between each season, but instead is defined by levels of precipitation. Heaviest precipitation occurs during the high sun period when the ITCZ (Inter-tropic convergence zone) moves into the region. Two reasons why a hurricane forms in the tropical region is because the air is warm, and there is a sufficient spin from the earth. The region with the most number of hurricanes is the west part of the north pacific, with an average of 17 a year. North of the equator hurricanes generally occur between August-September, where as south of the equator they occur between January-March.  ﻿[]

__Hurricane Characteristics __ Of all storms, hurricanes are the most powerful, although the wind speed is much less than tornados, hurricanes are bigger and have a longer life span. The average peak wind speed is around 90mph, but the most extreme speed measured was 210mph. Hurricanes form around areas of low sea level pressure, the average sea level pressure in the centre of a hurricane is 950mb, but pressures as low as 870mb have been recorded, and this makes the hurricane much more powerful and thus dangerous. Hurricanes range in size, but the average is 350 miles wide. A hurricanes life span can vary between several days, a week or even longer.

__Hurricane structure __ Hurricanes are a large number of thunderstorms arranged in a pinwheel formation, thick clouds spiral outwards from the storms centre. The pressure gradient, speed of winds and levels of precipitation increase closer towards the eye wall of the storm. The increase is gradual, but towards the eye wall the increase is more rapid. In the upper regions of the storm, ice crystals can form, due to lowered temperatures. These crystals then create a layer of cirrostratus clouds that obscure the structure of the hurricane. __Eye and Eye Wall __ The eye is situated in the centre of the hurricane, it has relatively clear skies and light winds. The average diameter of the eye is 20 miles, but it varies heavily with some as little as 3.5 miles, whilst others as large as 60 miles. The eye changes in size over time, this gives an indication whether the storm is intensifying or weakening, a shrinking eye means that the storm is intensifying. Surrounding the eye is the eye wall, where the storm is at its most intense, with fast winds, deep clouds and heavy precipitation with levels of 2500mm of rainfall per day. The eye wall reaches up to heights of 49,000ft above sea level. Large waves of over 10 meters high are experienced due to extreme winds. There is a huge difference in weather between the eye and its wall. As the centre of the hurricane approaches, wind and precipitation increases in intensity, until the eye is hit when the weather turns calm, this calm lasts between 1-2 hours, until the eye wall is once again reached. Portions of the eye wall contain hot towers, which are parts of the wall which rise to a greater height than the rest of the wall, when this happens it means that the storm will intensify within the next 6 hours. The temperature within the eye is several degrees warmer than outside the rest of the hurricane. The air is also dryer, because the warming of the unsaturated air lowers humidity. Although the weather within the eye is calm it is not cloud free, cumulus clouds are scattered throughout.  __<span style="font-family: 'Comic Sans MS',cursive;">﻿Reference __ <span style="font-family: 'Comic Sans MS',cursive;">﻿-Edward Aguado, James E Burt (2010) Understanding weather and climate, Forth edition <span style="font-family: 'Comic Sans MS',cursive;">-Donald Athrens (2007) Meteorology Today, Eighth edition