What are cyclones?



Cyclones are huge revolving storms caused by winds blowing around a central area of low atmospheric pressure. In the northern hemisphere, cyclones are called hurricanes or typhoons and their winds blow in an counter-clockwise circle. In the southern hemisphere, these tropical storms are known as cyclones, whose winds blow in a clockwise circle cyclone is an area of closed, circular fluid motion rotating in the same direction as the Earth.
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Cyclones are also called ....

Hurricane, typhoon, tropical storm, cyclonic storm, tropical depression, and simply cyclone.

How to Survive a Cyclone

1) Listen to the experts.
2) Have a disaster plan.
3) Keep an emergency kit close by and at hand.
4) Fill containers of water.
5) Prepare your home to survive a tropical storm by securing doors and windows.
6) Stay indoors and away from windows when the storm hits.


Where Do Cyclones Occur?


OCEAN BASIN
SEASON
AVERAGE CYCLONES
PER SEASON(winds above 63 km/h)

PERCENTAGE OF
GLOBAL TOTAL

SEVERE CYCLONES
PER SEASON(winds above 120 km/h)

North Indian
May to June & October to December
5.4
7%
2.5
Northwest Pacific
Mainly June to December
25.7
31%
16.0
Northeast Pacific
May to November
16.5
20%
8.9
North Atlantic
June to November
9.7
11%
5.4
Southwest Indian
December to April
10.4
12%
4.4
Southeast Indian/Aust
December to April
6.9
8%
3.4
Southwest Pacific
November to April
9.0
11%
4.3

What's the Damage?


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As you can see, the damage is pretty bad, this town is pretty much destroyed by the effects of a mighty cyclone. Cyclones are better known as hurricanes and can cause some serious damage almost about as quick as it comes. Damage may result in a major flood-up to 15 inches in water. Most of the damage is really not caused by the wind as much as the flying debris. An abnormal increase occurs in the ocean's water level, sometimes in an excess of several meters high. Probably a hurricane's most devastating feature, storm surges ravage low-elevation coastal areas. It is especially damaging when the storm surge occurs during high tide and, consequently, is often responsible for most hurricane-related deaths.


How they form?
Cyclones develop over warm oceans near the equator. As the warm air rises, it becomes loaded with moisture which condenses into massive thunderclouds. Cool air rushes in to fill the void that is left, but because of the constant turning of the Earth on its axis, the air is bent inwards and spirals upward with great force.
Size descriptions of tropical cyclones
ROCI
Type
Less than 2 degrees latitude
Very small/midget
2 to 3 degrees of latitude
Small
3 to 6 degrees of latitude
Medium/Average
6 to 8 degrees of latitude
Large anti-dwarf
Over 8 degrees of latitude
Very large[10]

Tropical Disturbances
A discrete tropical weather system of apparently organized convection - generally 200 to 600 km in diameter - originating in the tropics or subtropics, having a non frontal migratory character, and maintaining its identity for 24 hours or more. It may or may not be associated with a detectable perturbation of the wind field. Disturbances associated with perturbations in the wind field and progressing through the tropics from east to west are also known as easterly waves.



What else happens?


  • Tropical Disturbance
A discrete tropical weather system of apparently organized convection - generally 200 to 600 km in diameter originating in the tropics or subtropics, having a non frontal migratory character, and maintaining its identity for 24 hours or more.
  • Tropical Depression
    A tropical cyclone in which the maximum wind speed is up to. Depressions have a closed circulation.
  • Tropical Storm
    A tropical cyclone in which the maximum wind speed ranges from 34 kt . The convection in tropical storms is usually more concentrated near the center with outer rainfall organizing into distinct bands.
  • Hurricane
    When winds in a tropical cyclone equal or exceed 64 kt it is called a hurricane . Hurricanes are further designated by categories on the SAFFIR-SIMPSON SCALE

http://library.thinkquest.org/10136/cyclones/cycltq.htm
http://www.solar.ifa.hawaii.edu/Tropical/tropical.html
http://www.ask.com/wiki/Tropical_cyclone
http://www.aoml.noaa.gov/hrd/tcfaq/tcfaqHED.html