How a Cyclone is Formed Tropical cyclones are the greatest storms on earth releasing in one day as much condensation heat energy as up to four hundred twenty megaton atomic bombs. Every cyclone is dangerous and must be regarded as a real threat until the danger has clearly passed. In the southern hemisphere the winds spiral in a clockwise direction towards its centre where they rise and spill over in an outward flow at high altitude.
Summer heat beating on the warm ocean evaporates water creating a deep layer of moist air.
The uplift of this moist air in the centre of a low cools it causing the intense rain characteristic of tropical cyclones. Higher in the upper levels the rising air spirals outward removing air faster than it flows in resulting in a fall in barometric pressure. Cyclones vary greatly in character but the one feature they all have in common is a virtually calm centre. Around this eye are bands of heavy cloud associated with the moist air which spirals in towards the centre of the cyclone. As a cyclone moves forward at only approximately fifteen to twenty-five kilometres per hour there is usually sufficient warning time so that people can prepare for its onset.