How Cyclone Larry formed By Ashleigh Campbell Firstly, what is a cyclone? • As found in the Oxford Dictionary, a cyclone is a large-scale, atmospheric wind and pressure system characterized by low pressure at its centre and by circular wind motion, counter clockwise in the Northern Hemisphere, clockwise in the Southern Hemisphere. They only form over warm waters in the tropical areas of the oceans where the sea temperatures are 26.5°C or greater. How are cyclones caused? • Cyclones are caused by the warm air that lies over open waters. It is heated by the sun and rises very quickly, creating points with low air pressure. • That warm air becomes transformed into moisture which is absorbed by thunderclouds. • Cool air rushes to fill the empty spaces left by the warm air. How are cyclones caused? (continued) • Because of the continuous turning of the Earth on its axis, the air is bent inwards and begins to rotate upwards with great force. • The spiraling winds start to turn faster and faster and thus forms a massive circle of winds which can have a diameter of up to 2000 kilometers. • Winds created by the cyclone can reach speeds of 200km/h How did Cyclone Larry form? • The Tropical Cyclone Larry started as a low pressure system over the eastern Coral Sea. It formed into a tropical cyclone in the early hours of 18th May, and proceeded on a westerly track towards the Queensland coast. • Larry became a severe tropical cyclone at 10am on the 18th and continued to intensify as it approached the Queensland coast, reaching Category 4 early on the 19th. • The eye of Larry crossed the coast near Innisfail between 6:20am and 7:20am on the 20th March. Larry started to weaken after it hit landfall but maintained cyclone strength for several hundred kilometres inland until the early hours of the 21st. Cyclone Larry moved into western Queensland to the north of Mount Isa.