of the key elements that influence the forming of hurricanes is
a warm ocean surface.
When moist air
passes over the warm ocean it is driven upwards. Strong winds remove
the heat and encourage more warm air to rise. A chain reaction of
rising and sinking air begins, creating 'convection' currents, and
when the Earth's rotation adds a twist to this motion the hurricane
spiral is formed.
An increase of
2C in the surface ocean temperature of the hurricane zones by 2100
could drive tropical storms into a higher gear. In the 1970's, there
was an average of about 10 category 4 and 5 tropical cyclones per
year globally. Since 1990, the number has almost doubled, averaging
18 per year globally.