ch. 11: hurricanes - 11 - hurricane notes.pdf · storm tide facts •hurricane camille in 1969...
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Ch. 11: Hurricanes
Be able to
Define what hurricane is.
Identify the life and death of a hurricane.
Identify the ways we track hurricanes.
What are Hurricanes?
Smaller than mid-latitude
Dont have warm and cold fronts.
Most destructive storms on earth.
What/ Where are Hurricanes?
A hurricane is an intense tropical low-pressure area with sustained winds of 74mph or greater.
They circulate counter-clockwise about their centers in the Northern Hemisphere.
Most Hurricanes form between the latitudes of 5and 20
Whos # 1
North Pacific has the greatest number of storms. average 20 per year
U.S. Only averages 11 tropical storms, and 6 hurricanes in the Atlantic Ocean.
4 methods of gathering data on hurricanes1. Satellite
2. Reconnaissance aircraft
4. Data buoys
Hurricanes cause damage three ways:
1. Strong winds
2. Heavy rains
3. Storm Surge
The greatest damage associated
with hurricanes is caused by?
Storm Tide Facts
Hurricane Camille in 1969 produced a 24-foot storm tide in Mississippi.
Hurricane Hugo in 1989 generated a 20-foot storm tide in South Carolina.
Hurricane Katrina in 2005 generated a 27-foot storm tide in Mississippi.
North American hurricane season is normally from June to November.
The most active months in the Atlantic are: Aug. Oct.
The three Category 5 storms to hit the USA:
1. 1935 Florida Keys "Labor Day" hurricane.
2. Hurricane Camille, which hit Mississippi in 1969.
3. Hurricane Andrew, which hit Florida, on Aug. 24, 1992.
Birth of a Hurricane
Hurricanes are formed from complex of thunderstorms. The ocean water itself must be warmer than 80F. The heat and moisture from this warm water is ultimately
the source of energy for hurricanes.
Death of a Hurricane Hurricanes will weaken
rapidly when they: travel over land
travel over colder ocean waters
locations with insufficient heat and/or moisture.
Wind shear is defined as the amount of change in the wind's direction or speed with increasing altitude. Weak wind shear is good for tropical storm
development. Strong wind shear is bad for tropical storm development.
Hurricane Life Cycle
1) Tropical Disturbance or Wave
Most common, about 100 forming each season.
They lack a closed circulation
Wind speeds are less than 20 knots, or 25 mph.
Hurricane Life Cycle
2) Tropical Depression
A wave becomes a depression when there is a presence of a closed circulation, and sustained winds are 20 knots, or 25 mph.
At this point, the system is still quite disorganized.
Hurricane Life Cycle
3) Tropical Storm
A depression becomes a tropical storm when thunderstorm activity moves over the closed circulation, and sustained winds reach at least 35 knots, or 39 mph.
At this point, the system is capable of causing minimal damage, and the storm receives a name.
Example. - T.S. Katrina)
Hurricane Life Cycle4) Hurricane
A tropical storm becomes a hurricane when the closed circulation becomes an eye, and sustained winds reach at least 65 knots, or 74 mph.
At this point, the system is capable of causing significant damage.
* Sustained winds
A 1-minute average wind measured at
about 33 ft (10 meters) above the
Life Cycle of a Hurricane
Other Names for Hurricanes
Hurricane is given to systems that develop over the Atlantic or the eastern Pacific Oceans.
Typhoons in the western North Pacific and Philippines
Cyclones in the Indian and South Pacific Ocean
Saffir-Simpson Hurricane Scale A Category 1 storm has the lowest wind speeds, while
a Category 5 hurricane has the strongest.
The maximum sustained surface wind speed (peak 1-minute wind at 33 feet/10 meters) is the determining factor in the scale.
The Worst U.S Hurricanes Most Damage
Hurricane Katrina, August 2005, was the costliest
hurricane in history, racking up more than $80 billion
in damages. (#2 Hurricane Andrew, 1992 - $ 26 billion)
Galveston Hurricane 1900, 8,000 deaths attributed to
Hurricane Camille, which hit Mississippi with winds at
190 mph in 1969.
The 882 mb pressure reported in Hurricane Wilma in
2005 is the lowest central pressure on record in an
Hurricane Watch vs. Warning
HURRICANE WATCH: Hurricane conditions are possible. The hurricane watch is issued 48 hours in
advance of the anticipated onset of tropical-storm-force
HURRICANE WARNING: Hurricane conditions are expected. The hurricane warning is issued
36 hours in advance of the anticipated onset of tropical-