Hurricanes

Hurricane a storm system with a large low-pressure center with many thunderstorms produces strong winds and heavy rain

Tropical Cyclones Tropical Cyclones (the general word for hurricanes) form over warm ocean water Lose strength when they reach colder water or land. Start out as tropical storms When wind speeds get high enough, it is considered a hurricane: 74 mph

Effects Bring a storm surge when they reach land Floods coastal areas Can lead to coastal erosion They can also cause tornadoes

Crystal Beach a few days before and a few days after Hurricane Ike. Note how the grass is gone and the water is closer to the houses that are left.

The strip of brown is dead plants from the saltwater that swept over the coastal wetlands after Hurricane Ike. Much of this area had recently been hit by Hurricane Gustav.

Effects cont. (Storm Surge) Storm surge - Huge wave, or wall of water, created at leading edge of hurricane. Size of storm surge depends on size of hurricane Salt water destroys plants along the coast Affects animal life as well—many animals drown

Effects cont. The destruction of wetlands and coastline is common during a hurricane. Barrier islands help protect the mainland, but some of them are disappearing due to weathering and erosion by hurricanes and other causes

Coastal Erosion The Chandeleur Islands are a group of barrier islands off the coast of Louisiana. Today there are few recognizable landforms left on the Chandeleur Island chain.

The islands have been getting smaller and moving landward since the late 1800s.

Sand and sediment is deposited on the landward side of the islands while land is lost on the seaward side of the islands.

Several strong hurricanes have contributed to a faster decline in the size of the islands.

Many factors, including human activity along the Mississippi River such as dams and levees, have led to sand and silt not being deposited fast enough. The Chandeleur Islands may disappear within a few decades.

Effects cont. (Coastal Erosion) Coastal erosion is the removal of land or beach sediments Can happen without hurricanes Hurricanes make coastal erosion worse Barrier islands are most vulnerable to coastal erosion

Effects cont. (Flooding) Hurricanes can produce a lot of rain which causes inland flooding This is freshwater flooding Also harms plant and animal life

Saffir-Simpson Scale Used to measure hurricanes Measures TD, TS, and Category 1-5 Does not accurately predict storm surge for hurricanes that have been larger Hurricane Ike was a Category 2 storm when it came shore, but had a Category 4 size storm-surge

Cyclone Categories 19+Catastrophic> Extreme Extensive Moderate Minimal Storm Surge (feet) Damage at Landfall Wind Speed (mph) Category The Saffir-Simpson Hurricane Scale

Integrated Kinetic Energy A new scale used by scientists that better predicts a storm’s destructive power Measures the total kinetic energy a storm has Takes into account the size of the storm, wind speed, waves, and storm surge Hurricane Ike had the highest IKE of any Atlantic storm