General Science 1Spring ‘08

Hurricane SeasonOccurs between June 1-November 30Threatens the Gulf Coast of the US, Eastern

Coast, Mexico, Central America and Caribbean“hurricane” in the Atlantic ocean“typhoon” in Asia“cyclone” in Australia

Hurricane Terms

Tropical depression Rita

Tropical storm Boris

A tropical cyclone (low pressure area) that occurs in the North Atlantic.

Tropical depression- winds less than 39 mph

Tropical storm- Winds between 39-74 mph and given a name

Hurricane- winds 75mph or greater

Characteristics of HurricanesTropical- form in tropical areas near equator

with water temps. near 80oF.Cyclonic- winds swirl around a central eye

Counter clock wise in northern hemisphereClock wise in southern hemisphere

Low-pressure systems- eye is always a very low pressure

Parts of a hurricaneEye- low pressure center, calm areaEye wall- area around the eye, fastest, most

violent windsRain bands- bands of thunderstorms

circulating outward from the eye; feeds the storm

Begin off west coast of Africa as thunderstorms

They move east over warm, tropical waters

Warm, moist air over the ocean rises quickly, condenses and forms clouds

Rising air is replaced by warm, humid air from below.

Cycle continues, drawing warm air inward.

Circulation and wind speeds increase

Air moves from areas of high to low pressure, so more air is pulled inward, feeding the hurricane

It can take several hours or days for a hurricane to form

Size and LocationHurricanes vary widely in sizeCan spread out over hundred to thousands of

miles

Hurricane Danny (left) in 1997 and Hurricane Fran in 1996 show the

variability in hurricane size

Watches and WarningsTropical Storm Watch- 39-75 mph winds

possible within 36 hoursTropical Storm Warning- conditions likely

within 24 hrsHurricane watch- hurricane conditions

possible within 36 hoursHurricane warning- hurricane within 24 hrs

DamageCaused by:

Rain (up t0 40 inches!)Flooding (due to the rain)Winds (75 mph or greater)Storm surge

wall of water that comes in front of a hurricane Created by wind Increases flooding/erosion

tornadoes

Damage Depends on 3 Things1. Strength of storm2. If it hits land3. Right or left side of eye strikes an area-

right is worse (winds/rain stronger)

Saffir-Simpson Scale

Hurricane Isabella as a Cat. 1 on 9/19/05

Category 174-95 mph windsSome floodingLittle to no damage

Category 296-110 mph windsTrees downRoof damageflooding

Saffir-Simpson Scale

Category 3111-130 mph windsStructural damage to

homesMobile homes

destroyedSevere floodingLoss of life

Category 4131-154 mph windsSever flooding inlandMajor structural

damage (roofs ripped off)

Loss of life

Saffir-Simpson Scale

Hurricane Katrina as a Category 5 on August 28,

2005. One day before making

landfall on the Gulf Coastwww.hurricanekatrina.com

Hurricane Andrew (1992)

Category 5Greater than 155 mph

winds!Severe flooding further

inlandSevere damage to most

wooden structuresLoss of life

Money to RebuildFEMA- Federal Emergency Management Agency

Created in 1979Headquarters in Washington, DCA small agency with only 2,600 full-time

workers, and nearly 4,000 other workers called Disaster Assistance Employees. These workers are on stand-by to respond after

a disaster happens.

Became part of the Department of Homeland Security on March 1, 2003.

In charge of helping people before and after a disaster.

Called in to help when the President declares a disaster.

Disasters are “declared” after hurricanes, tornadoes, floods, earthquakes or other similar events strike a community.

Hurricane KatrinaOne of the five deadliest hurricanes in US

history.6th strongest Atlantic hurricane ever

recorded.3rd strongest hurricane on record to make

landfall.Formed on August 23, 2005.

Hurricane KatrinaMost severe damage in New Orleans, LA.At least 1,836 people lost their lives.Estimated $81.2 billion in damage (2005)

making it the costliest natural disaster in US history.

Political AftermathPoor response by FEMABut the National Hurricane Center and the

National Weather Service were widely commended for accurate forecasts and abundant lead time.