Hurricanes are powerful cyclonic storms that form over warm ocean waters and have sustained winds over 74 mph. They have a counter-clockwise rotation and low atmospheric pressure at the center. The hurricane season runs from June to November in the Atlantic. Hurricanes gain their energy from heat released by water evaporation. They have an eye, rainbands spiraling inward, and outer bands spiraling outward. Strength is measured by wind speed and pressure. The costliest hurricanes in recent US history have caused extensive damage and flooding due to increased development in vulnerable coastal areas.

1. HURRICANES
The History, Structure,
Development, and Destruction
Source: http://www.dc.peachnet.edu/~pgore/students/w97/matheson/hpage.htm

2. What is a hurricane?
 Violent
cyclonic storm
that develops
in the tropical
region
 Wind speeds
are > 74 mph Source: http://earthobservatory.nasa.gov/
Newsroom/NewImages/images.php3?img_id=680

3. Rotation and Pressure
In which direction does a hurricane
rotate?
COUNTERCLOCKWISE
Is the atmospheric pressure inside the
hurricane high or low?
LOW

4. When is Hurricane Season?
June 1st
through
November
31st

5. What is the role of the
National Weather Service
during hurricane season?
 Provides weather information,
such as data from satellites
 Responsible for issuing watches
and warnings to the media and
general public

6. Watch vs. Warning
 What is the difference between a
Hurricane Watch and a Hurricane
Warning?
 Watch – Tropical storm poses a threat to
coastal areas within 36 hours
 Warning - Tropical storm conditions are
expected in a coastal area within 24 hours

7. What conditions must be present
for a hurricane to develop?
 Warm ocean temperatures
(>80˚ F) up to 60m deep
 Little to no wind shear
(change in wind direction
as you go higher into the
atmosphere)
 Low pressure system at
least 5˚ North or South of
Equator
 Rotation caused by winds
Source: http://lwf.ncdc.noaa.
gov/oa/reports/fran/fran.html

8. What is the major source of
energy fueling a hurricane?
Heat Energy evaporating from
the ocean surface
Source: http://ww2010.atmos.uiuc.edu/(Gh)/guides/mtr/hyd/evap.rxml

9. Hurricane Anatomy
Source: http://hurricanes.noaa.gov/prepare/structure.htm

10. Another look at the Structure
Source: http://hurricanes.noaa.gov/prepare/structure.htm

11. Comparison of Terms
 Tropical Disturbance
Group of thunderstorms in the tropics that are
present for at least 24 hours
 Tropical Wave
lack of circulation, winds <25 mph in every
direction
 Tropical Depression
closed circulation but disorganized, winds at least
25 mph.

12. Comparison of Terms
Tropical Storm
Shower and thunderstorm moves over closed
circulation, winds greater than 39 mph
Hurricane
Eye is developed, winds > 74 mph

13. Compare the Following
Source: http://ww2010.atmos.uiuc.edu/(Gh)/guides/mtr/hurr/stages/home.rxml

14. By what two factors is hurricane
strength measured?
Wind Speed
Barometric (air) Pressure

15. What is the Scale Used to
Categorize Hurricanes?
Saffir-Simpson Scale
Category Max Wind Speed
(mph)
Min. Surface
Pressure (mb)
Storm Surge m
(ft)
1 74-96 > 980 1-1.7 (3-5)
2 97-111 979-965 1.8-2.6 (6-8)
3 112-131 964-945 2.7-3.8 (9-12)
4 132-155 944-920 3.9-5.6 (13-18)
5 > 155 < 920 > 5.7 (>19)
Source: http://kids.earth.nasa.gov/archive/hurricane/saffir-simpson.html

16. What causes the
damage in a hurricane?
Winds
Flooding
Storm Surge

17. What is a storm surge?
 Large wall or dome of
water that rushes into
the coastline as a
result of a hurricane
making landfall
 To the right are the
areas affected by high
storm surges
Souce: http://www.wkrg.com/hurricanecenter/surge/SE.jpg

18. What destroys a hurricane?
 Strong vertical winds
 Cold water
 Movement over land
 Friction
 Lack of moisture

19. What are the five costliest
hurricanes in the United States?
1. Hurricane Katrina – 2005 (105 billion)
2. Hurricane Andrew – 1992 (45 billion)
3. Hurricane Ike – 2008 (27 billion)
4. Hurricane Wilma – 2005 (20 Billion)
5. Hurricane Ivan – 2004 (19 billion)

20. Explain why the majority of the
costliest storms are relatively recent
 Damage is a
result of
development
 There are more
developed
areas and
possessions
than in the past
Source: http://www.nhc.noaa.gov/1992andrew.html

21. What are the five deadliest
hurricanes in the United States?
1. Galveston – 1900 (8,000)
2. Southeast Florida – 1928 (2,500)
3. Katrina – 2005 (1200)
4. Chenier Caminanda – 1893 (1100 –
1400)
5. Sea Islands – 1893 (1000-2000)

22. Explain why the deadliest storms
were mostly longer ago.
 Lack of weather instruments to predict and
track storms
 People were not warned of the incoming
danger
Source: http://www.1900storm.com/photographs/photo10.html
Results of the Galveston Hurricane

23. http://cindi.usgs.gov/cindi/hazard/event/floyd/ncflood/mediums/img023.jpg
Mrs. Parker’s
Old House
Final Water Level
Flooding of Tar River as result of
Hurricanes Dennis and Floyd
Dockside
Tar River
Estates

24. Damage to Greenville
 Extensive Flooding
 Extended Power
outages
 Flood Related
Deaths
 Property Damage
US 264 Bridge
Source: http://cindi.usgs.gov/cindi
/hazard/event/floyd/ncflood/
mediums/img022.jpg

25. Damage to Greenville
Source: http://www.guc.com/about/floyd.htm

26. Protection
 Listen to warnings
 Take all warnings seriously
 Follow evacuations
 Prepare Food and Water for
extensive power outages

27. Source: http://www.dc.peachnet.edu/~pgore/students/w97/matheson/hpage.htm