Cyclone

edited January 2018 in Geography

WHAT IS CYCLONE?

A tropical cyclone is a rotating, organized system with winds, clouds and thunderstorms that originates over tropical or subtropical waters and has a closed low-level circulation.
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A cumulonimbus cloud, a tropical cyclone has so many of these; they form huge, circular bands.
HOW DO CYLONES FORM?
 Cyclones Needs Water to Form and Grow.
 A Cyclone begins as a group of thunderstorms moving over tropical ocean waters.
 Thunderstorms form in areas of low pressure.
 As long as a Cyclone stays above warm water, it can grow bigger and more powerful.

CYCLONES REQUIRE CERTAIN CONDITIONS FOR THEIR FORMATION
A source of warm, moist air derived from tropical oceans with sea surface temperature normally near to or in excess of 27 °C.
Winds near the ocean surface blowing from different directions converging and causing air to rise and storm clouds to form
Winds which do not vary greatly with height - known as low wind shear. This allows the storm clouds to rise vertically to high levels;
Coriolis force / spin induced by the rotation of the Earth. The formation mechanisms vary across the world, but once a cluster of storm clouds starts to rotate, it becomes a tropical depression. If it continues to develop it becomes a tropical storm, and later a cyclone/ super cyclone.

WHY CYCLONES FORM IN TROPICAL REGION?
 Tropical cyclones are like giant engines that use warm, moist air as fuel.
 Near the equator, warm ocean water provides the energy that can turn a low-pressure center into a violent storm. That is why they form only over warm ocean waters near the equator.
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 The warm, moist air over the ocean rises upward from near the surface. Because this air moves up and away from the surface, there is less air left near the surface. Another way to say the same thing is that the warm air rises, causing an area of lower air pressure below.

MAJOR FORCES HELP TO FORM CYCLONE IN TROPICAL REGIONS
These forces controls the path of winds and ocean currents in the world , so we have to understand the forces first to know how these forces play an important role in any region’s climate or formation of cyclone.
1. PRESSURE GRADIENT FORCE
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The change in pressure measured across a given distance is called a "pressure gradient".
The pressure gradient results in a net force that is directed from high to low pressure and this force is called the "pressure gradient force".

 Air from surrounding areas with higher air pressure pushes in to the low pressure area. Then that "new" air becomes warm and moist and rises, too. As the warm air continues to rise, the surrounding air swirls in to take its place.
 As the warmed, moist air rises and cools off, the water in the air forms clouds. The whole system of clouds and wind spins and grows, fed by the ocean's heat and water evaporating from the surface.

2. CORIOLIS FORCE

 Storms that form north of the equator spin counterclockwise.
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 Storms south of the equator spin clockwise.
 This difference is because of Earth's rotation on its axis which is called Coriolis force.


CYCLONE’S EYE
As the storm system rotates faster and faster, an eye forms in the center. It is very calm and clear in the eye, with very low air pressure. Higher pressure air from above flows down into the eye.
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If you could slice into a tropical cyclone, it would look something like this. The small red arrows show warm, moist air rising from the ocean's surface, and forming clouds in bands around the eye. The blue arrows show how cool, dry air sinks in the eye and between the bands of clouds. The large red arrows show the rotation of the rising bands of clouds.
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When the winds in the rotating storm reach 39 mph, the storm is called a "tropical storm." And when the wind speeds reach 74 mph, the storm is officially a "tropical cyclone," or hurricane.

WHEN CYCLONE DIES
Tropical cyclones usually weaken when they hit land, because they are no longer being "fed" by the energy from the warm ocean waters. However, they often move far inland, dumping many inches of rain and causing lots of wind damage before they die out completely.

CYCLONE CAN CAUSE EXTENSIVE DAMAGE

 A cyclone can pound a coast with huge waves and sweep the land with strong winds and heavy rains.
 When a cyclone moves into a coastal area, it pushes a huge mass of ocean water known as a storm surge.
 A storm surge can be the most destructive and deadliest part of a hurricane that causes flooding.

HOW CAN YOU PREPARE FOR A CYCLONE?

 Plan Ahead – Have a storm supply kit that contains a battery-operated radio, batteries, flashlights, candles, rain jackets, tarps, blankets, bottled water, canned food, and medicines.
 Listen to safety announcements.
 Plan a safety route. A safety route is a planned path to a safe place.
 During severe weather, it is important to listen to local radio or TV stations. Severe weather updates will let you know the location of the storm.



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