Great question! There are usually several large
hurricanes that affect the U.S., Mexico, and
Caribbean each year. These huge storms also occur
in the Pacific, where they are known as cyclones.
So why do hurricanes happen so often? The general
answer is that the ocean transfers a lot of heat
to the air in the summer time. This heat is a form
of energy and can cause violent storms. How much
heat? I read one estimate that a hurricane can
expend as much energy (heat is energy) as 10,000
nuclear bombs in its cycle (Grtozinger et al.,
2007)! However this energy is expended over a huge
area and over a long time, so it is not as
powerful as a nuclear explosion.
Hurricanes usually originate near the equator in
the summer time, where ocean surface waters are
very warm (usually above ~250 C or 77 F).
Warmer ocean waters mean more heat is
transferred to the air above the ocean. As the air
rises, it condenses and forms clouds and rain.
Condensation of water releases heat; it is the
exact opposite of putting heat into water to turn
it to vapor. This heat that is released causes air
to rise faster. When the hot air rises, it leaves
behind a low pressure zone above the water beneath
it. More air flows toward the low pressure, and
the cycle keeps on going. All of the air moving
from high to low pressure zones causes heavy winds
(sometimes greater than 150 miles per hour), and
the condensed water vapor causes heavy rains.
Grotzinger, J., Jordan, T., Press, F., Siever, R.
(2007). Understanding Earth 5th edition. New York:
W.H. Freeman and Company.
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