As Tropical Storm Isaac churns ominously in the Gulf of Mexico, a Gulf Coast landfall is predicted nearly seven years to the day since Hurricane Katrina slammed into New Orleans.
As millions prepare for the as yet unknown havoc Isaac (a projected Category 1 hurricane) will wreak once the storm reaches land, we focus on what makes these enormous storms so dangerous.
What Makes a Hurricane
Known as cyclones and typhoons in other parts of the world, hurricanes are giant, spiraling tropical storms that can pack wind speeds of over 160 miles an hour and unleash more than 2.4 trillion gallons of rain a day.
Hurricanes begin as tropical disturbances in warm ocean waters with surface temperatures of at least 80 degrees. These low pressure systems are fed by energy from the warm seas. When a storm achieves wind speeds of 38 mph, it is classified a tropical depression. A tropical depression becomes a tropical storm, and is given a name, when its sustained wind speeds top 39 mph. When a storm’s sustained wind speeds reach 74 mph it becomes a hurricane.
Hurricanes are enormous heat engines that generate energy on a staggering scale. They draw heat from warm, moist ocean air and release it through condensation of water vapor in thunderstorms. Hurricanes spin around a low-pressure center known as the “eye.” Although this 20- to 30-mile-wide area is notoriously calm, the eye is surrounded by a circular “eye wall” that hosts the storm’s strongest winds and rain.
These storms bring destruction ashore in many different ways. When a hurricane makes landfall it often produces a devastating storm surge that can reach 20 feet high and extend nearly 100 miles. Ninety percent of all hurricane deaths result from storm surges.
A hurricane’s high winds are also destructive and may spawn tornadoes. Torrential rains cause further damage by triggering floods and landslides. The unpredictability of these immense storms makes them even more dangerous; they often change direction, path, speed and strength.
As Isaac lumbers slowly toward land, Angel MedFlight is keeping all of our Gulf Coast neighbors in our thoughts.