Hurricanes: Structure, Damage, Classification, and Case Study

Hurricane

Organized tropical cyclones with thunderstorms rotating counterclockwise (NH).

Eye

Calm center of storm.

Eyewall

Surrounding intense thunderstorms and strongest winds.

Rainbands

Spiral bands of storms around the eye.

Small hurricanes

Stronger winds due to a steeper pressure gradient.

Large hurricanes

Cover more area and push more water ashore (storm surge).

High Winds

Strongest on eastern side of storm; forward motion adds to sustained wind on east side.

Storm Surge

Abnormal rise of sea level during hurricane; worst in low-lying coastal areas.

Hurricane size

Influences storm surge.

Wind speed & pressure

Factors that influence storm surge.

Tide level at landfall

Influences storm surge.

Hurricane Katrina (2005)

Category 3 winds, but 21 ft storm surge → destruction like Category 5.

Saffir-Simpson Scale

Classification based only on sustained wind speed.

Category 1

74-95 mph winds.

Category 2

96-110 mph winds.

Category 3

111-129 mph winds.

Category 4

130-156 mph winds.

Category 5

157+ mph winds.

Tropical Disturbance

Unorganized thunderstorms.

Tropical Depression

20-38 mph winds, weak rotation.

Tropical Storm

39-73 mph winds, eye starts to form.

Naming of Hurricanes

Early US hurricanes named by location; now use male & female names on a 7-year rotating list.

Destructive hurricanes' names

Retired after significant damage (e.g., Katrina, Camille, Matthew, Isaac).