How do tropical storms form?
Tropical storms occur between 5* and 30* north and south of the equator. Find out how they form below.
Tropical Storms start within 5º and 30º north and south of the equator where surface sea temperatures reach at least 26.5ºC. The air above the warm sea is heated and rises. This causes low pressure. As the air rises it cools then condenses, forming clouds. The air around the weather system rushes in to fill the gap caused by the rising air. The air begins to spiral. This is caused by the spinning movement of the earth.
The weather system generates heat which powers the storm, causing wind speeds to increase. This causes the tropical storm to sustain itself. Tropical storms rely on plenty of warm, moist air from the sea – this is why they die out over land.
What is the structure of a Tropical Storm?
The central part of the tropical storm is known as the eye. The eye is usually between 30-50km across. It is an area of calm, with light winds and no rain. It contains descending air. Large cumulonimbus clouds surround the eye. These are caused by moist air condensing as it rises. Wind speeds average 160km per hour around the eye.
1. Hurricane Katrina – America’s costliest hurricane.
2. Hurricane Andrew – 1992 America’s second costliest hurricane
4. Indian ‘Super Cyclone’ 1999 Orissa cyclone – The strongest and deadliest cyclone in the region since the Bangladesh cyclone of April 1991
5. Cyclone Eline – 2000 The cause of the major disaster in Mozambique
For more information on current hurricanes visit the US National Hurricane Centre website.
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