Wednesday, February 2, 2011

Australian Tropical Cyclones


As Tropical Cyclone Yasi heads towards the Queensland coast, today’s Fun Fact Wednesday discusses the phenomena of cyclones in Australia.

The Australian cyclone season runs from 1st November to 30th April. They are generated by warm ocean temperatures of 26.5oC or higher, resulting in water evaporation that forms clouds. The rotation of the Earth then causes these cyclone clouds to rotate.

To be classified as a cyclone, wind speeds must exceed 63km/h. The severity of a cyclone is graded on a scale from 1 to 5, with 5 being the most extreme with winds above 280km/h resulting in almost total destruction on land. TC Yasi has been classified as category 5.

The names of cyclones are taken from a list of 104 names used by the Australian Bureau of Meteorology. Up until 1975, all of the names selected were female but now cyclones are given male and female names alternately. Cyclone names are reused unless the cyclonic event has a significant affect on Australia – such as TC Tracy. When a name is retired it is replaced by a name on a supplementary list. The Bureau  of Meteorology accepts requests for new names to be added to the supplementary list in writing.

1 comment:

Anonymous said...

Great stuff!