Hurricanes Hurricanes

I: Observed characteristics I: Observed characteristics

Images from journals published by the American Meteorological Society are copyright © AMS and used with permission. Images on pages 9, 22, and 23 are copyrighted by Oxford, NY: Oxford University Press, 2005. Book title is Divine wind: the history and science of hurricanes. ISBN: 0195149416. Used with permission.

What is a Hurricane? What is a Hurricane?

Formal definition: A tropical cyclone with 1-min average winds at 10 m altitude in excess of 32 m/s (64 knots or 74 MPH) occurring over the North Atlantic or eastern North Pacific

The wordThe word HurricaneHurricane is derived from the Mayanis derived from the Mayan wordword HuracanHuracan and the Taino and Carib wordand the Taino and Carib word

HunrakenHunraken, a terrible God of Evil, and brought to, a terrible God of Evil, and brought to the West by Spanish explorersthe West by Spanish explorers

This image has been removed due to copyright restrictions.

Early historical encounters: The Mongol invasions of Early historical encounters: The Mongol invasions of Japan in 1274 and 1281 Japan in 1274 and 1281

This image has been removed due to copyright restrictions.

Scene from the 13th century Mongol invasion scrolls, based on a narrative written by the Japanese warrior Takezaki Suenaga.

Airborne Radar: Horizontal Map

360 km (220 mi)

Airborne Radar: Vertical Slice

20 km (12 mi)

120 km (75 mi)

Azimuthal wind

Temperatureperturbation at constant altitude

Radial wind Radial wind

Vertical velocity Vertical velocity

AngularAngularmomentummomentumper unit massper unit mass

M rV sin r 2

Global Tropical Cyclones, 1949-2006

1950 1960 1970 1980 1990 2000 0

20

40

60

80

100

120A

nnua

l Glo

bal S

torm

Cou

nt

Year

North Atlantic Tropical Cyclones, 1949-2006

1950 1960 1970 1980 1990 2000 0

5

10

15

20

25

30A

nnua

l Sto

rm C

ount

Year

In Atlantic, the Frequency of Storms is Well Correlated with In Atlantic, the Frequency of Storms is Well Correlated with Tropical Atlantic Sea Surface Temperatures Tropical Atlantic Sea Surface Temperatures

Num

ber

of S

torm

s

Scal

ed T

empe

ratu

re

Yearscovered:1870-2006

Better Intensity Metric: Better Intensity Metric:

The Power Dissipation Index The Power Dissipation Index

PDI V 3 dtmax0

A measure of the total frictional dissipation of kineticA measure of the total frictional dissipation of kinetic energy in the hurricane boundary layer over the lifetimeenergy in the hurricane boundary layer over the lifetime of the stormof the storm

Three Analyses of Tropical Cyclone Power Dissipation in the Western North Pacific, and SST in the Main Development Region

Yearscovered:1949-2004

In the Atlantic, Power Dissipation and SST are Exceptionally WelIn the Atlantic, Power Dissipation and SST are Exceptionally Well lCorrelated through the Modern Instrumental Record Correlated through the Modern Instrumental Record

Yearscovered:1970-2006

Atlantic Sea Surface Temperatures and Storm Maximum Power Dissipation

(Smoothed with a weighted filter)

Scal

ed T

empe

ratu

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Pow

er D

issi

patio

n In

dex

(PD

I)

Yearscovered:1870-2006

Infamous U.S. Hurricanes Infamous U.S. Hurricanes

Galveston, 1900 Galveston, 1900

Image courtesy of NOAA.

Miami, 1926 Miami, 1926

Image courtesy of NOAA.

Okeechobee Hurricane of 1928 Okeechobee Hurricane of 1928

Image courtesy of NOAA.

Labor Day Hurricane of 1935, Florida Keys Labor Day Hurricane of 1935, Florida Keys

Indian Key absolutely swept clean, not a blade of grass, and oveIndian Key absolutely swept clean, not a blade of grass, and over ther the high center of it were scattered live conchs that came in with thigh center of it were scattered live conchs that came in with the sea,he sea, craw fish, and dead morays. The whole bottom of the sea blew ovecraw fish, and dead morays. The whole bottom of the sea blew over it.r it.

-- Ernest HemingwayErnest HemingwayImage courtesy of NOAA.

Andrew, 1992 Andrew, 1992

Image courtesy of NOAA.

Hurricane Katrina, 2005 Hurricane Katrina, 2005

Image courtesy of NOAA.

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12.103 Science and Policy of Natural Hazards Spring 2010

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