How are Hurricanes Created?
The birth of a hurricane requires at least three conditions. First, the
ocean waters must be warm enough at the surface to put enough heat and
moisture into the overlying atmosphere to provide the potential fuel for
the thermodynamic engine that a hurricane becomes. Second, atmospheric
moisture from sea water evaporation must combine with that heat and
energy to form the powerful engine needed to propel a hurricane. Third,
a wind pattern must be near the ocean surface to spirals air inward.
Bands of thunderstorms form, allowing the air to warm further and rise
higher into the atmosphere. If the winds at these higher levels are
relatively light, this structure can remain intact and grow stronger:
the beginnings of a hurricane!
Often, the feature that triggers the development of a hurricane is some
pre-existing weather disturbance in the tropical circulation. For
example, some of the largest and most destructive hurricanes originate
from weather disturbances that form as squall lines over Western Africa
and subsequently move westward off the coast and over warm water, where
they gradually intensify into hurricanes.
Take a Tour|
Take a VR Tour of a hurricane, and see
how the winds within a hurricane interact.
The Most Killed
The 1900 Galveston, Texas, hurricane took 6,000 lives -- more than any
other natural disaster in United States history. Click here for more information about hurricane
There are now some 45 million permanent residents along the
hurricane-prone U.S. coastline -- and the population is still growing.
Florida, where hurricanes are most frequent, also leads the United
States in new residents. In addition, holiday, weekend, and vacation
populations swell in some coastal areas.
Destroy the Hurricane?
NOAA and its predecessor tried to weaken hurricanes by dropping silver
iodide into the rainbands of the storms. The idea was that the silver
iodide would enhance the thunderstorms of the rainband helping it to
grow at the expense of the eyewall. Two hurricanes were massively seeded
with silver iodide: one in 1969 and one in 1971. The first storm
weakened temporarily after the seeding; there was no effect on the
second. The hurricane seeding program was discontinued in 1972 because
of budget cuts. Later analysis of the 1969 storm suggested that it
would have weakened even if the seeding had not occurred.
National Hurricane Center
The National Hurricane Center
(NHC) maintains a continuous watch on tropical cyclones over the
Atlantic, Caribbean, Gulf of Mexico, and the Eastern Pacific.
Find out more about Hurricanes.