Stormy weather

Press, 16 March 1982, Page 20

Stormy weather

What do Dorothy from “The Wizard of Oz” and Tonga have in common? The answer is very little, apart from cyclones which whisked the Kansas girl to Oz and devastated the Pacific Islands.

A’ cyclone is wind spinning in a huge circle round an area of low air pressure. The wind does not have to be strong, but it usually is and does a great deal of damage. It blows in a circle that can measure up to 1600 km across — the shortest distance between New Zealand and Australia.

North of the equator the winds turn in an anti-clock-wise direction; in the Southern Hemisphere they turn the opposite way, in a clockwise direction. This is because of the earth’s rotation.

Because the wind and rain of the cyclone can do so much damage in destroying buildings and endangering people’s lives weather offices in various countries monitor their path using radar and satellites.

Warnings are issued so that people can prepare for the storm. The storms are given a name, (in alphabetical order for easy reference). The latest cyclone was

Cyclone Isaac, which swept through the Pacific two weeks ago, cutting Tonga off for two days. Two people were killed in the storm. The calm area in. the centre of the cyclone is called the eye of the storm. When the eye arrives it seems as if the storm is over but the calm passes and the wind returns.

Cyclones usually start out at sea and the winds create huge waves that sometimes cause flooding. Torrential rain comes with the wind. The low pressure cyclone, with its rain, is followed by a high pressure anti-cyclone, in which colder, drier air circles down towards the earth bringing fine weather. Different names are given to wind storms in different parts of the world. As well as cyclones there are tornados and typhoons. A storm officially becomes a hurricane when the winds reach speeds of 116 kilometres per hour. India has a monsoon season when heavy rains come and the Canadians have a warm wind they call a Chinook. Chinook is an Indian word that means “snow-eater” and the wind is called that because it melts the snow.