Lucy+Natalie-+Hurricane+Formation

=Hurricane Formation= by Natalie and Lucy Blue

Hurricane basics-

 * A hurricane is an intense tropical, low-pressure area with winds of 120km/hour or more.
 * average 300-600 km in diameter
 * called cyclones in the Indian ocean
 * called typhoons when they begin in the Eastern Pacific Basin and make landfall in Asia
 * Hurricanes typically exist for weeks

=What do you need for a hurricane to form?=

Warm ocean water
Hurricanes use warm ocean water as their fuel. Atlantic Basin hurricanes develop off the coast of Africa because the water is between 10º and 30º north is around 80ºf. This is the lowest temperature that water can be in order for a hurricane to form. That is why hurricanes only form in tropical regions. From there, they are fueled by other ingredients to gain power and move northbound towards places like the coast of Florida and the Gulf of Mexico.

Wind
The circulation pattern of both water and wind north of the equator is clockwise. That means that any tropical storm developing off the coast of west Africa is going to be moved further northwest because of the fueling circulation pattern of the northern hemisphere. The northeast trade winds are the prevailing winds off the coast of Africa that drives the developing tropical storms to our region of the southern US and tropical islands. The Southeast Trade Winds have the same affect on the storm. The trade winds also help to fuel the storms because they are traveling at the same speed as the hurricanes. This causes the hurricanes to stay in the same path of the trade winds through out their lifetime. One way that scientists predict the path of hurricanes is the future paths of the winds that the storms are traveling with.

Weather
The reason that hurricanes and the beginnings of hurricanes thrive in places like the equator is because the weather there is the warmest. Hurricanes are fueled by the water temperature like stated before. As we learned in other units through out the year, the sun is strongest near the equator, not to mention staying directly on the equator through out the duration of the year. The continuous heat from the sun beating on the water heats the surface layer (to about 200 ft. in depth) to around 80 degrees. We all know about the sun in the northern hemisphere is strongest during the months of summer and somewhat into fall. The season of hurricanes for the Atlantic basin and the northern hemisphere is June 1st through November 30th. Notice that the sun is able to do the same thing in the northern hemisphere during this period that it does to the equator through out the year. The sun heats the water in the northern hemisphere (though not to the extent of the equatorial region) to further fuel the hurricanes after they are formed.

Air pressure
Areas of low pressure (off the coast of Africa and in equatorial regions) circulate counter-clockwise. Areas of high pressure circulate in a clockwise direction. The reason why hot air moves to cold and cold to hot is because of equilibrium (balance). Equilibrium is the same reason why high pressure will move to areas of low and low to high. Because both pressures are moving in different directions, the exchange of air pressures creates a circulation pattern directly off the coast of Africa. The general circulation pattern moves in a counter-clockwise direction (same as the wind patterns of the northern hemisphere) to create the counter-clockwise circulation pattern (called cyclonic rotation) of the hurricanes of the Atlantic basin. This picture doesn't represent the air pressure circulation off the coast, but demonstrates the circulation of air pressure in general.

Location
Hurricanes feed off of the Earth spinning and the Coriolis Effect. The Coriolis Effect is the strongest and the North and South poles. It is also weakest at the Equator. Since this effect is necessary, Hurricanes can't form within 5**º** of the equator (also known as the Doldrums). With this in mind, the hurricanes still have to be close to the equator for the warm water. This puts many forming hurricanes on the northwest coast of Africa.

Watch this Satellite video of a forming Hurricane:
Notice how the Coriolis Effect brings the hurricane northwest... media type="youtube" key="IYNgD5qguLY"

Remnants of Mid-Latitude Storm
Hurricanes don't just form out of nowhere. Storms off the coast of Africa leave remnants of rain, wind, etc. that are kept together to actually create the beginning of the hurricane.

Refrence to...

 * Hurricane/Wind/Coriolis Notes
 * October Hurricane Test
 * Chapter 28 Atmospheric Pressure and Winds Notes (about 10/22/06)
 * Chapter 30 Cyclonic Storms Notes (about 10/22/06)