HURRICANES

Presented by:Catherine Charnawskas &Margaret MilliganJuly 31, 2004SCE 6103

The Atmosphere's Largest Event

Storm Types

Tropical Storm• Tropical cyclone with 39

to 74 mph winds• Forms over a tropical

ocean• Center of the storm is

warmer than surrounding air

• Strongest winds near Earth’s surface

• Has no fronts• 200 to 500 miles wide

Extratropical Storm• Dominant weather

systems of continents• Forms outside the

tropics• Center of the storm is

cooler than the surrounding air

• The strongest winds are in the upper atmosphere

• Has fronts – warm and cold

• 700 to 1000 miles wide

What is a Hurricane?

A hurricane is a tropical cyclone with winds greater than 74 mph.The typical hurricane width is 300 miles across.

How to make a hurricane•One part warm ocean water

•Above 80° F & 200 ft deep•One part warm and humid air•One part weak upper level winds•Lots of energy!

3% of a hurricane’s energy is transferred into wind andwaves.

Typhoons and Indian Ocean Cyclonesare related to hurricanes.

Hurricanes can easily last more thana week. Atlantic hurricanes candevastate Caribbean islands severaldays before hitting the United States mainland.

How a hurricane develops

Hurricane season in the Atlantic ranges from June to November withthe peak in September.

1. A tropical depression forms over warm ocean water. This willeventually develop into a tropical storm.

2. Humid air rises.3. When water vapor in rising air condenses into water droplets it

releases heat. This is called latent heat.4. Latent heat warms surround air making it lighter.5. The lighter air rises.6. As warm air rises, more air flows in to replace it. This causes

wind.7. On the advancing side of the storm, smaller thunderstorms,

tornadoes, and other inclement weather is generated.8. The eye of the hurricane is calm with wind speeds at nearly zero

mph. The pressure in the eye is far below normal sea level pressure. Looking up through the eye of the hurricane an observer will see cloudless skies.

Anatomy of a Hurricane

Day Twelve: The hurricane continues to weaken after hitting land often called extratropical at this stage.

Where can I find a Hurricane?

15% East Pacific Ocean

12% Western Atlantic Ocean 12% South Indian Ocean

30% Western NorthPacific Ocean

12% North Indian Ocean

12% South Pacific Ocean

7% North and WestAustralia

Each year about 100 tropical storm form in the world. 66% develop into hurricanes (Atlantic/East Pacific), typhoons (West Pacific), or cyclones (Indian Ocean).

Naming Hurricanes

2004AlexBonnieCharleyDanielleEarlFrancesGastonHermineIvanJeanneKarlLisaMatthewNicoleOttoPaulaRichardSharyTomasVirginieWalter

2005ArleneBretCindyDennisEmilyFranklinGertHarveyIreneJoseKatrinaLeeMariaNateOpheliaPhilippeRitaStanTammyVinceWilma

2006AlbertoBerylChrisDebbyErnestoFlorenceGordonHeleneIsaacJoyceKirkLeslieMichaelNadineOscarPattyRafaelSandyTonyValerieWilliam

Names are different for each region.Names are both male and female.Names are alphabetical and alternate between male and female.

Experience shows that the use of short, distinctive given names in written as well as spoken communication is quicker and less subjectto error than the older more cumbersome latitude-longitude identification methods. These advantages are especially important inexchanging detailed storm information between hundreds of widely scattered stations, coastal bases, and ships at sea.

Saffir-Simpson Scale

Saffir-Simpson Scale

Strength

Wind Speed

Storm Surge

Pressure

(MPH) (Feet) (Millibars)

Category 1 74- 95 mph 4-5 feet >980 mb

Category 296-110

mph 6-8 feet 965-979 mb

Category 3111-130

mph 9-12 feet 945-964 mb

Category 4131-155

mph 13-18 feet 920-944 mb

Category 5 >155 mph 18+ feet 919 mb

DID YOU KNOW?

Hurricane forecasters consider New Orleans America’s most dangerous for storm surge, since a storm could drive 20ft of water into the city.

Hurricane Watch – threat within 24-36 hours

Hurricane Warning – threat within 24 hours or less

Hurricanes...Devastating?

The low pressure and high winds associated with hurricanes create huge mounds of water called STORM SURGES which cause 90% of all hurricane deaths.

Hurricane winds have been recorded at speeds up to 200 mph.

Beyond the direct damage by such winds, wind-driven waves on top of the storm surge compound the flooding problem by battering and eroding the coastal landscape and structures.

Storm surge – a huge mound of water created by the low pressure and strong winds of a hurricane. They are found especially in shallow coastal waters. They can increase the water level as much as 20 feet!

Wind damage – damage caused by high winds as well as waves driven by high winds.

Two devastating factors of a hurricane:

Hurricane Mitch

Facts about Mitch•Oct 22 – Nov 9, 1998•Category 5•Lowest pressure: 905mb•Highest winds: 180mph•Rainfall: between 300 and 1800mm. •1200 mm recorded in one day in Honduras. This is the yearly average for New England!

Strongest hurricane since theGreat Hurricane of 1780!

Hurricane Mitch

Facts about Mitch• Death toll of about 11,000• Thousands missing• 3 million homeless• $5 billion in damages• Starvation, Malaria, and Cholera were widespread• Crop loss estimated at $900 million• Estimated that it will take 15 to 20 years to rebuild parts of Honduras.

Text References

Demillo, Rob. How Weather Works Ziff-Davis Press, Emeryville, California 1994, 121-129

Williams, Jack. The Weather Book 1st Edition 1992 Vintage Books, New York, New York, 131-151

American Meteorological Society Project Atmosphere “Hazardous Weather Teacher’s Guide” 1992 pg 21-24

Allaby, Michael. How the Weather Works Reader’s Digest, Pleasantville, New York. 1995. 84-87

Internet Sources/Resources

• http://www.weather.com – The Weather Channel• http://www.weatherbug.com – WeatherBug. A

downloadable program that gives you current weather for your area. Great way for students to collect weather data over time.

• http://www.miamisci.org/ - Great site for hurricane information and activities (and other areas of science too!)

• http://www.nws.noaa.gov/ - National Weather Service

• http://www.wunderground.com – Weather Underground, another great site for collecting weather data around the United States and world.