Cyclones are huge revolving storms caused by winds blowing around a central area of low atmospheric pressure. In the northern hemisphere, cyclones are called hurricanes or typhoons and their winds blow in an anti-clockwise circle. In the southern hemisphere, these tropical storms are known as cyclones, whose winds blow in a clockwise circle.

Cyclonic-force winds may be encountered all over the globe, but it is only above the warm seas of the tropics that  a ripple of instability in the air can become a genuine  cyclone, the deepest of all low-pressure weather systems.

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