A cyclone is an area of closed, circular fluid motion rotating in
the same direction as the Earth. This is usually characterized by inward spiraling winds that
rotate counter-clockwise
The main source of energy for tropical
cyclones is the warm oceans in the tropical regions. To initiate a tropical
cyclone the sea-surface temperature generally needs to be above 26.5°C.
The development of a tropical cyclone
also relies on favorable broad-scale wind regimes and can persist for several
days with many following quite erratic paths.
As the air moves toward the center of
the disturbance, it “curves” or “spirals”, rather than flowing in a
straight line.This spiral effect comes from the rotation of the Earth – as air
moves over large distances, the Earth moves underneath it, producing a spiral
effect.
When the winds in the rotating storm
reach 39 mph (63 kmph), the storm is called a “tropical storm”. And when the
wind speeds reach 74 mph (119 kmph), the storm is officially a “tropical
cyclone” or hurricane. Tropical cyclones usually weaken when they hit land,
because they are no longer being “fed” by the energy from the warm ocean
waters. However, they often move far inland, dumping many centimeters of rain
and causing lots of wind damage before they die out completely.
