Facts about cyclones
CYCLONES are intense, violent storms characterised by high-speed winds rotating clockwise around a tropical low-pressure system, producing torrential rain, that often leads to flooding.
Tropical cyclone intensity is defined by the maximum average wind speed over open flat land or water. The severity of a cyclone is described in categories from 1 to 5, which are determined by the maximum wind speed.
In order to be identified as a cyclone, it must be travelling over 119km per hour and it must have been formed over the ocean in a tropical region.
According to the Bureau of Meteorology, Australia has, on average, 13 cyclones a year.
Tropical cyclones in the Southern Hemisphere spin clockwise.
The average life of a cyclone is three to seven days.
Cyclones are assigned names, which are chosen from a list.
Cyclone Tracy (1974) has been Australia’s most destructive cyclone to date.