Tropical Cyclones
- This means a cyclone
-- low pressure
cell in the
atmosphere
- That develops,
has its origins,
in tropical
latitudes
Other Names for
Tropical Cyclones
- Hurricane -- Atlantic
Ocean
- Typhoon -- Pacific and
Indian oceans
Most powerful,
most destructive cyclonic storm ~
- Develop over
subtropical oceans ~
- 8-15 deg N & S
latitudes
- Starts as a weak low
- Ocean temperatures
over 27C (80F) required
- Once formed, moves
westward in Tradewind belt
- Westerly winds can
steer it NW, N, NE ~
- Path much less
predictable than desired
Schematic diagram
of a hurricane
- Almost circular ~
- Extremely low pressure
~ ~
- Diameter -- 150-500 km
(100-300 mi)
- Winds spiral inward at
very high speed ~
- Center is clear of
clouds ~
- Hurricane wind speeds
-- 120-200 km/hr (75-125 mph) and higher
- Central eye clear
because of descending air
- Eye walls of very high
cumulonimbus -- rising
- Storm renews itself
because of release of latent heat
- Runs "out of
gas" over land
- Tracks difficult to
predict exactly
- Map of hurricane
tracks show belts of origin and impact ~
Seasonality of
hurricanes -- only certain seasons
- May - November in N
Atlantic ~
- Late summer - early
autumn = max
- Follows Intertropical
Convergence Zone
- How many in a year? ~
- How long do they last?
~
Great difficulty in
forecasting/predicting paths of hurricanes
- Many dollars at stake,
plus lives
- Money may be spent in
preparation, then hurricane doesn't arrive
- If no preparation,
hurricane may arrive and lives and property lost
Hurricane Impacts
~
- Winds
- Flooding -- coastal
plains
- Storm surge -- and
high tide
Public
Responsibility -- Government Action
- When should hurricane
landfall be forecast?
- Financial impact to
prepare -- even if storm doesn’t occur where predicted
- Should people live in
hurricane prone zones?
- Should government
provide warning?
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