I.
Hurricanes
A. Hurricane Stages
B.
C.
D.
E.
F.
G.
H.
a. Tropical Cyclone
i. large center of low pressure, strong winds, & intense rain
ii. forms over warm water near equator
iii. Stormy weather acts as a seed.
Tropical Depression
a. Surface wind of tropical cyclone are sustained @ 61 km/h
Tropical Storm
a. Winds 117 km/h or less
b. Named
Hurricane
a. Minimum one minute sustained winds 119 km/h (74 mi/h) or greater
b. Called typhoons in West N. Pacific Ocean
c. Called cyclones in Indian Ocean
Hurricane Building
a. Heat is supplied from warm ocean water near the equator
b. Evaporates into the atmosphere
Coriolis Effect
a. Controls the direction in which a cyclone spins
i. N. Hemisphere spins counterclockwise
ii. S. Hemisphere spins clockwise
iii. Effect is weakened at the equator
Eye of the Hurricane
a. Calm center of storm
i. Lowest atmospheric pressure
Anatomy of a Hurricane
a. Eye
i. Relatively calm with clear weather
ii. About 30-60 km across
iii. Air sinks
b. Eye wall
i. Power vertical winds raises the air upward
ii. Spirals
c. Rain bands
i. Contains T.S. that range in a few km-10’s of km wide
ii. Drop10 cm of rain in one hour
d. Upward motion of air
i. Generates VERY low atmospheric pressure
ii. Creates severe wind speed as air moves inward from higher atmospheric
pressure area
I.
J.
K.
L.
M.
N.
Hurricane Classification
a. Cat 1
i. 119-153 km/hr (74-95 mi/hr)
b. Cat 2
i. 154-177 km/h
c. Cat 3
i. 178-209 km/h
d. Cat 4
i. 210-249 km/h
e. Cat 5
i. Greater than 250 km/h
Hurricane Movement
a. Depends on atmospheric conditions around it
i. Forward speed 25-32 km/h
ii. Can be as fast as 95 km/h
iii. Slow hurricanes bring torrential rain & flooding
iv. Usually stay in the tropic
v. Right side is most dangerous
Hurricane life span
a. Hurricanes that make landfall last about 5 days
b. Hurricanes that remain over the ocean tend to last about 2 weeks
c. Die out using energy creating winds & rain, upper winds tear them apart, move over
cool water, and/or over land energy is cut off energy is overcome by friction
Storm surge
a. Hurricane waves
i. Can reach 12 m (40 ft.)
ii. Cause about 90% of deaths
iii. Worse if hurricane hits land during high tide
Galveston Hurricane
a. Deadliest natural disaster
i. 600 lives lost
ii. Topography averages 1.5 m above sea level
Hurricane Andrew
a. FL’s most severe weather
i. 3rd largest in history
b. Eye decreased strengthening the hurricane
i. Radius of maximum winds was 18 km
ii. Wind speeds 258 km/h (160 m/h)
c. 25 billion in damages
i. 65 lives lost
ii. 250,00 homeless
iii. Dade county  99% mobile homes destroyed
iv. Returned to gulf toppling drilling platforms resulting in an additional 2 billion in
damages
O. Hurricane Katrina
a. Most destructive hurricane to EVER strike U.S. in 2005
i. 4th largest of all time.
b. Hit S. FL as a Category 1.
i. Strengthened in Gulf & doubled in size Cat 5
ii. Winds 280 km/h (175 mi/h)
iii. Lowest recorded central pressure @ 902 mb
iv. Hit land as a Cat 3
P. Destruction from Katrina
a. Affected FL-TX
a. Most destruction resulted from the storm surge (6-9 m; 20-30 Ft.)
b. Levee system failed
i. Floodwaters reached 9 m (30 ft.) for weeks
Q. Katrina’s impact on the economy
a. Oil production in gulf was greatly reduced
i. Decreased 1.4 million barrels per day (95%)
ii. Gas reached a record price 5 days after the storm.
R. Deadliest Hurricane
a. Loss
i. 1.7 million people lost power for weeks
ii. Water unavailable in New Orleans
iii. Airports flooded & closed
iv. Interstate 10 & other roads destroyed or impassable
v. 1,836 people lost his/her lives
S. 4 Years later
a. Effects still felt
i. Thousands sill living in trailers
ii. Cost reached $60 billion in insured losses