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The terms
"hurricane" and "typhoon" are regionally specific names for a
strong "tropical cyclone". A tropical cyclone is the generic term
for a non-frontal synoptic scale low-pressure system over tropical
or sub-tropical waters with organized convection (i.e. thunderstorm
activity) and definite cyclonic surface wind circulation (Holland
1993).
Tropical cyclones
with maximum sustained surface winds of less than 17 m/s (34 kt,
39 mph) are called "tropical depressions". (This is not to be
confused with the condition mid-latitude people get during a long,
cold and grey winter wishing they could be closer to the equator
) Once the tropical cyclone reaches winds of at least 17 m/s they
are typically called a "tropical storm" and assigned a name. If
winds reach 33 m/s (64 kt, 74 mph)), then they are called: a "hurricane"
(the North Atlantic Ocean, the Northeast Pacific Ocean east of
the dateline, or the South Pacific Ocean east of 160E); a "typhoon"
(the Northwest Pacific Ocean west of the dateline); a "severe
tropical cyclone" (the Southwest Pacific Ocean west of 160E or
Southeast Indian Ocean east of 90E); a "severe cyclonic storm"
(the North Indian Ocean); and a "tropical cyclone" (the Southwest
Indian Ocean) (Neumann 1993).
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