Hurricanes usually originate as a cluster of showers and thunderstorms in tropical
waters. The process by which a disturbance forms and subsequently strengthens into
a hurricane depends on many conditions. However, there are three major factors which must be met before hurricane formation. Those factors include warm water and moisture, favorable low level winds, and light upper level winds.
A hurricane's main source of energy comes from heat. Developing hurricanes gather
heat and energy through contact with warm ocean waters. Most of the time in the
hurricane generation season ocean water temperatures are warmer than 79 degrees.
Winds near the ocean surface need to rotate counterclockwise (low pressure) in
order for a cluster of storms to develop into a tropical system. This
counterclockwise flow directs winds and moisture inward
to a central point. Once this moisture nears the central point, the center of a
low pressure system, it is lifted into the atmosphere to form more showers and
thunderstorms. As this process repeats itself, the
more energy and moisture is available; and the area of showers and thunderstorms
grows and intensifies, leading to the formation of a tropical system.
The upper portion of the atmosphere is to a hurricane what a muffler is to a car.
All of the exhaust from a car must go somewhere so it goes through a hollow tube
(muffler) into the open air. If an object is
placed in the muffler or it is clogged, the car will not run properly. The same
situation can be applied to tropical systems. All the upward moving moisture and
water vapor (exhaust) in the center of the low
must go somewhere. Upper levels of the atmosphere act as the tropical system's
muffler". In an ideal situation, light upper level winds will allow this moisture
to be "fanned out" to other parts of the storm. If
there are strong winds aloft, they act as a lid to the "muffler" and the moisture
has no place to go. Hence, the storm has no means to intensify and may even
collapse if the upper level winds are strong enough.
What are the different parts of the hurricane?
The typical hurricane has 2 or 3 and sometimes more outer convective bands. These
bands are comprised of cells resembling ordinary thunderstorms and can be up to
300 miles from the eye. The outer
convective bands are generally 40 to 80 miles apart and come in advance of the
main rain shield.
The rain shield is a solid or nearly solid area of rain that typically becomes
heavier as one approaches the eye. The outer edge is well defined and its distance
from the eye varies greatly from storm to storm.
The wind, both sustained and peak gusts, keeps increasing as one moves through the
rain shield toward the storm's eye.
Spiral convective rings or bands are the regions of active showers and
thunderstorms than encircle the centers of tropical cyclones. They are prevalent
in more intense hurricanes and curve cyclonically
inwards toward the center of the storm where they appear to merge and form the
wall of the eye.
The eye wall is an organized band of thunderstorms that immediately surrounds the
center or eye of a hurricane. It's generally around 15 miles wide and typically
contains the fiercest winds and most intense
The eye is a relatively calm center of the hurricane. The winds are light, and
skies are partly cloudy or even clear. The average hurricane eye diameter is a
little over 20 miles. In general, when the eye is
shrinking in size, the hurricane is intensifying. During the daytime, the passage
of the hurricane's eye over a community is usually accompanied by sunny skies and
a rise in temperature. After the eye's passage,
the violent wind howls in the opposite direction to what it was right before the
eye moved over and the heavy sheets of rain return.
Hurricanes from when a group of thunderstorms come together to form
one big storm.Closer to the equator, sea water is very warm and the
air has a lot of moisture in it. These two factors help storms grow
into hurricanes. The moisture in the air becomes rain, and the warmth
of the sea water provides energy that eventually becomes wind.
But how do regular storms start? Air is different in different places
around the earth and at different times. Some air is over land, some
over mountains, and some over lakes and oceans. Sometimes the sun is
shining on it and sometimes it isn't. An important property of air is
called pressure. It is a measure of energy that says how much the air
is pressing or pushing on the air around it. Wind spins around places
where the pressure is low, like water in a whirlpool. Low pressure
also helps turn the moisture in air into rain.
So it is around low pressure areas that storms form, and it is in
certain places where the air is warm and moist that stroms grow
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