Hurricane Formation and Categories

• Hurricanes can cause devastation and destruction.
• Hurricane Katrina (2005), Hurricane Irene (2011), and Superstorm Sandy (2012) caused major damage and many deaths in the U.S.

Hurricane Development

• Hurricanes begin as small storms that grow into larger, more dangerous ones.
• A tropical depression is a tropical spinning storm with wind speeds less than 39 mph.
• A tropical storm is a tropical spinning storm with wind speeds between 40 and 73 mph.
• A hurricane is a tropical spinning storm with wind speeds above 74 mph.

Hurricane Categories

• Hurricanes are categorized from 1 to 5, with danger and damage increasing as the number increases.
• A category 1 hurricane is the weakest, with wind speeds of 74 - 95 mph.
• A category 5 hurricane is very dangerous and causes extensive damage, with wind speeds of 155 mph and more.
• Hurricane Andrew in 1992 was a category 5 hurricane.
• All hurricanes, even category 1, can be dangerous and damaging.

Hurricane Formation

• Hurricanes travel west across the Atlantic due to prevailing tropical winds, and rarely hit the West Coast of the United States.
• Tropical winds blow from east to west, originating in Africa and moving toward the Caribbean, Mexico, and the Southeast U.S.
• Hurricanes develop over oceans and tend to dissipate once they hit land.
• Over tropical oceans, warm, moist air rises, creating thunderstorms.
• Water from the air cools and condenses, eventually falling back to land as heavy rain.
• Horizontal diversion of wind causes the air to spiral, forming a tropical depression.
• Condensation releases energy as heat, intensifying the storm into a tropical storm or hurricane.
• Condensation produces rain and helps the storm rise.
• Rising air sucks up surface air, creating a low-pressure area in the center, also known as the 'eye' of the hurricane.
• The eye of the storm is calm compared to the surrounding winds and rain.

Hurricane as a Heat Engine

• A hurricane is a self-sustaining heat engine.
• Condensation releases heat, drawing moist air from the ocean.
• Moist air cools, leading to more condensation and heat generation.
• The cycle continues indefinitely unless disrupted.

Hurricane Dissipation

• Hurricanes stop when strong winds disrupt the flow over the ocean or when the storm moves over land.
• Over land, the hurricane runs out of fuel (water) and cannot sustain the cycle.
• The ocean provides the energy for a hurricane to grow.
• Hurricanes need a continuous supply of energy, so they weaken quickly over land.
• States bordering the Gulf of Mexico and Atlantic Ocean are most susceptible to hurricanes.

Hurricanes are categorized from 1 to 5, with danger and damage increasing as the number increases. A category 5 hurricane is very dangerous and causes extensive damage, with wind speeds of 155 mph and more. All hurricanes, even category 1, can be dangerous and damaging.