Wednesday, 20 March 2013

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Causes of hurricane

There are two main factors that causes hurricane storms which are vaporize warm water and high speed of wind. Hurricanes occur when the moist warm air from the surface of the ocean rises and meets cooler air. In that situation, the moist warm air condenses and produce storm clouds and raindrops. It also release of suppressed heat due to condensation process, which upsurges the temperature of the cooler air.


Highway in New Orleans
As the sequence of exchanging heat remains, a wind pattern is generated that moves in a spiral fashion around a calm center, which is referred to as the hurricane eye.  Existence of strong winds at high altitude pull the rising warm air away from the center, makes the storm to twirl in the usual hurricane pattern. 


Road to Florida Avenue, America


Another factor that increases the speed of wind is high-pressure air at high altitude. This high-pressure air draws the heat away from the center of the storm. As this high-pressure air moves to the center and meets the low-pressure air, the wind speed again increases.

How do hurricanes form?

Tropical cyclones are like giant engines that use warm, moist air as fuel. That is why they form only over warm ocean waters near the equator. The warm, moist air over the ocean upsurges upward from near the surface. Because this air travels up and away from the surface, there is fewer air left near the surface. Another way to say the similar thing is that the warm air rises, causing an area of lower air pressure below.

A cumulonimbus cloud. A tropical cyclone has many of these, they form huge, circular bands. 



Air from surrounding atmosphere with greater air pressure pushes in to the low pressure zone. Then that "new" air becomes warm, humid and rises, too. As the warm air remains 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 produce clouds. The entire system of clouds, wind spins and grows, fed by the ocean's heat and water vaporizing from the surface.

Storms that form north of the equator turn counter clockwise. Storms south of the equator spin clockwise. This variance is because of Earth's turning on its axis.

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 density. Higher pressure air from above flows down into the eye.


This is the diagram of the process on how hurricane occur


Video :

video
http://www.youtube.com/watch?feature=player_embedded&v=4f45jA5UxB0#!

Thursday, 7 March 2013

What Is Hurricane?

Hurricane is a violent storm which is characterized by extreme ferocity and hasty changes of the wind, and generally escorted by rain, thunder, and lightning especially prevalent in the East and West Indies. and also used figuratively.

Hurricane Katrina view from somewhere in America


In a scientific definition, hurricane means a severe, rotating tropical storm with heavy rains and cyclonic winds exceeding 74 mi (119 km) per hour, especially such a storm occurring in the Northern Hemisphere. Hurricanes is original came from the tropical parts of the Atlantic Ocean or the Caribbean Sea and move generally northward. It will lose its force when it move over land or colder ocean waters. Hurricanes can bring a lot of damage and effect towards an area which is affected. This natural disaster can make a country become unstable in many aspects such as political, economy, social relationships and financial.

The hurricane's view from satellite

Tropical cyclones categories :

Category
Wind Speed (mph)
Damage at Landfall
Storm Surge (feet)
1
74-95
Minimal
4-5
2
96-110
Moderate
6-8
3
111-130
Extensive
9-12
4
131-155
Extreme
13-18
5
Over 155
Catastrophic
19+