Perfect Conditions Make for Perfect Storms - How Hurricanes Form
Author: Mark Decherd

If you've ever wondered why hurricanes arrive like
clockwork during "hurricane season," it's because
conditions are just right. With the warm waters of late
summer, low pressure systems, and other conditions in
place, hurricanes are born.

Hurricanes start out as low pressure weather systems over
Africa and emerge as tropical disturbances over the warm
waters of the Atlantic Ocean during the late summer and
early fall. The moisture and warmth energize these low
pressure disturbances, creating thunderstorms. Some
thunderstorms dissipate and that's the end of the story.
However, many pickup strength and wind speed. When these
storm systems continue developing and winds have reached 40
miles per hour, they are then designated as tropical storms
and given a name from the National Hurricane Center. Once
a storm is named, it isn't necessary destined to become a
full-blown hurricane. In fact, many tropical storms fizzle
out. Others intensify, continuing to drawn energy from the
warm, moist waters below while venting cooler, dry air out
above. Energy and heat is released and strong winds form.
Meanwhile the center of the storm heats up due to the
release of energy and water vapor, causing an air pressure
drop and stronger, more intense winds in the core. This
creates a cycle of more heat, continued low pressure, and
stronger winds.

Finally, if the winds reach 74 miles per hour, the named
tropical storm becomes a Category One hurricane. Hurricanes
can vary in strength, moving up and down the Saffir-Simpson
scale as they lose or gain intensity. For example, when
hurricanes reach land, they quickly weaken because they are
no longer fueled by warm waters. However, many move over
the land, back to open waters where they quickly regain
their lost strength.

Category One hurricanes are the least destructive with
winds ranging from 74-95 miles per hour. Downed trees,
damaged bushes, and damaged mobile homes are typical
victims of Category One hurricanes.

Category Two hurricanes have winds ranging in speed from
96-110 miles per hour and typically bring storm surges of
6-8 feet above normal. Category Three hurricanes feature
winds from 111-130 miles per hour and 9-12 foot storm
surges. Category Four hurricanes are characterized by wind
speeds of 13-155 miles per hour and storm surges of 13-18
feet above normal. Finally, Category Five hurricanes have
winds in excess of 156 miles per hour and storm surges
above 18 feet.

Obviously, as hurricanes work their way up the scale with
stronger winds and larger storm surges, the potential for
damage increases dramatically. Only a few category five
hurricanes have made landfall in the U.S. However, lower
rated hurricanes can wreak havoc when conditions are right.
Hurricane Katrina, the most devastating hurricane to hit
the United States, made landfall as a Category Three
hurricane.

While hurricanes are destructive as far as man and
civilization are concerned, they do have beneficial
qualities. One, they provide up to a quarter of the annual
rainfall in the southern states and may even play a vital
role in maintaining the Earth's heat balance - moving heat
from the tropical regions to the poles. Hurricanes have a
long term positive effect on marshes and coastal wetlands
as well with storm surges adding critical nutrients and
sediment to these fragile lands. Under the sea, coral
benefits from hurricanes as well. For example, cooler
waters move to the surface, counteracting the "bleaching"
effect of warm waters. In addition, some species of coral,
such as elkhorn coral, break off of reefs and reattach
elsewhere, forming a new reef. Though capable of extreme
destruction, hurricanes help build up barrier islands which
in turn provide the first line of defense against the
hurricane's fury.

Warm ocean waters coupled with tropical disturbances and
low pressure systems each summer and fall provide the
perfect conditions for a hurricane to form. Whether a
tropical depression progresses to a tropical storm or a
hurricane depends on the conditions at the time. As summer
approaches fall, these conditions are perfect for a storm.


About the Author:

Mr. Mark Decherd is a husband, father and CEO of a small
business, born in Montreal Canada. He grew up in the states.
http://www.dryout.net