Hurricanes

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Conditions Required for Conditions Required for FormationFormation

• Warm, Humid Air (mT air mass)Warm, Humid Air (mT air mass)– form over tropical oceansform over tropical oceans

• Warm Water; 80 FWarm Water; 80 F

• Mainly form in the Fall; off the coast Mainly form in the Fall; off the coast of Africaof Africa

Why do Hurricanes travel Why do Hurricanes travel from east to west?from east to west?

None at theEquator!

The Stages of a HurricaneThe Stages of a Hurricane(based on changes in wind speed)(based on changes in wind speed)

1.1.Tropical DepressionTropical Depression

(L pressure system)(L pressure system)

2. Tropical Storm- gets a 2. Tropical Storm- gets a namename(39-74 mph)(39-74 mph)

3. Hurricane (over 74 mph)3. Hurricane (over 74 mph)

The Saffir-Simpson Hurricane The Saffir-Simpson Hurricane Damage Scale Damage Scale

Central Pressure

WindSpeeds

StormSurge

ObservedDamage

mb mi/hr feetinches knots meters

1>=980

>=28.9474-9564-82

4-5~1.5

some damage to trees, shrubbery, and unanchored mobile homes

2965-979

28.50-28.9196-11083-95

6-8~2.0-2.5

major damage to mobile homes; damage buildings' roofs, and blow trees down

3945-964

27.91-28.47111-13096-113

9-12~2.5-4.0

destroy mobile homes; blow down large trees; damage small buildings

4920-944

27.17-27.88131-155114-135

13-18~4.0-5.5

completely destroy mobile homes; lower floors of structures near shore are susceptible to flooding

<27.17>155>135

>18>5.5

extensive damage to homes and industrial buildings; blow away small buildings; lower floors of structures within 500 meters of shore and less than 4.5 m (15 ft) above sea level are damaged

Scale Number

Also Known as…Also Known as…

•TyphoonsTyphoons in the western Pacific in the western Pacific•Cyclones Cyclones in Australia/Indian in Australia/Indian oceanocean

•Hurricanes in the AtlanticHurricanes in the Atlantic

2011 Atlantic hurricane 2011 Atlantic hurricane seasonseason

First storm formed June 28, 2011

Last storm dissipated November 12, 2011

Strongest stormOphelia – 940 mbar (27.77 in Hg), 140 mph (220 km/h)

Total depressions 20

Total storms 19

Hurricanes 7

Major hurricanes (Cat. 3+) 3

Total fatalities 100 direct, 14 indirect

Total damage $12.2 billion

Timeline of 2011 Timeline of 2011 hurricaneshurricanes

Irene; cat 4 Aug. 20-28Irene; cat 4 Aug. 20-2855 dead; 10 billion $ 55 dead; 10 billion $ damagedamage

Katia- Aug. 25- Sept. 10; Katia- Aug. 25- Sept. 10; cat.4cat.4

Hurricane Ophelia Sept.. Hurricane Ophelia Sept.. 2011 cat. 42011 cat. 4

Parts of a hurricaneParts of a hurricane

• eye - 20-50eye - 20-50– light winds light winds – Air sinkingAir sinking– clear/broken clouds clear/broken clouds

• eye walleye wall – very strong winds very strong winds – ring of intense ring of intense

thunderstormsthunderstorms

Parts of a hurricane (cont.)Parts of a hurricane (cont.)

• Spiral Rain bands- heavy rain; windSpiral Rain bands- heavy rain; wind

Cross section of a hurricaneCross section of a hurricane

Eye Wall

Do Hurricanes affect Do Hurricanes affect Detroit?Detroit?

•Just rainJust rain

Hurricane Damage!Hurricane Damage!

Hurricane Hurricane DamageDamage

•due to due to windwind and and waterwater

•rains can cause flooding and rains can cause flooding and mud slidesmud slides

•Most deaths are due to the storm Most deaths are due to the storm surgesurge

Gulf Shores, AL (after Hurricane Ivan 2004)Gulf Shores, AL (after Hurricane Ivan 2004)

Power of Power of WindWind

Andrew 1992Andrew 1992

Ivan 2004

Iris 1991Iris 1991

STORM SURGESTORM SURGE

OCEAN WATER SUCKED UPWARD

Katrina’s storm surgeKatrina’s storm surge

Factors Affecting Storm Factors Affecting Storm SurgeSurge

•shape of the coastlineshape of the coastline

•the magnitude of the the magnitude of the hurricanehurricane

http://www.comet.ucar.edu/nsflab/web/hurricane/313.htm

What to do if a hurricane What to do if a hurricane warning is issued?warning is issued?

LEAVE THE AREALEAVE THE AREA

Hurricane forecastingHurricane forecasting

• Satellites are most useful in Satellites are most useful in detecting where hurricanes aredetecting where hurricanes are

• To predict direction they will go…To predict direction they will go…– FrontsFronts– Water temp.Water temp.– Wind directionsWind directions– Still fickle!Still fickle!

Hurricane DissolvingHurricane Dissolving

•storm passes over storm passes over coolercooler waters waters OR OR

•storm makes storm makes landfalllandfall

Once the warm water is gone so is the Once the warm water is gone so is the hurricane!hurricane!

What Determines What What Determines What is the Worst Hurricane?is the Worst Hurricane?

Winds ??Winds ??

Deaths ??Deaths ??

Cost ??Cost ??

Most Most PowerfulPowerful Atlantic Atlantic HurricanesHurricanes

Wilma- Oct. 2005Wilma- Oct. 2005lowest recorded pressure= lowest recorded pressure= 26.04”26.04”

Wilma 2005

DeadliestDeadliest Atlantic Hurricanes Atlantic Hurricanes

Galveston 1900-deadliest Galveston 1900-deadliest natural disaster in U.S. natural disaster in U.S. historyhistory

CostliestCostliest Atlantic Hurricanes Atlantic HurricanesKatrina- estimated $80 billionKatrina- estimated $80 billion

Andrew 1992Andrew 1992

Cost of hurricane damage is Cost of hurricane damage is increasing because….increasing because….

• More people are moving to hurricane More people are moving to hurricane prone areas!prone areas!

So, Which is So, Which is Worse?Worse?

HurricaneHurricane

AndrewAndrewThe Urban The Urban

StormStorm

•15 deaths15 deaths

•$26 billion in $26 billion in damagedamage

HurricaneHurricane

MitchMitchThe Rural StormThe Rural Storm

•11,000 deaths11,000 deaths

•very little very little monetary monetary damagedamage

HURRICANE KATRINA HURRICANE KATRINA 20052005

Levees brokeLevees broke

• Added to floodingAdded to flooding

• New O. below sea level!New O. below sea level!

Gulfport, MississippiGulfport, Mississippi

• Wind side of stormWind side of storm

Hurricanes

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