By Jonny Lupsha, Wondrium Staff Writer
Hurricane Ian hit Cuba September 28 and continued up the East Coast. The intense storm left dozens dead and millions without power. Hurricanes’ low-pressure cores facilitate winds.
Cuba and much of the United States suffered intense damage from Hurricane Ian last week as the storm battered Eastern North America. Its widely varying ferocity caused it to defy regular categorization, ranging from a tropical storm to a Category 4 hurricane. The entire island of Cuba and millions of people in Florida were left without power. More than a dozen were reported dead in Florida, before Ian reached the Carolinas.
Tropical cyclones become hurricanes or typhoons after becoming strong enough in tropical regions. In his video series Oceanography: Exploring Earth’s Final Wilderness, Dr. Harold J. Tobin, Professor in the Department of Earth and Space Sciences at the University of Washington in Seattle, analyzes what makes a hurricane.
How Hurricanes Work
“Hurricanes have a low-pressure core and the wind comes in from all directions to try to fill in that low-pressure core,” Dr. Tobin said. “The hurricanes build in intensity over the warm ocean water because as long as they’re over that warm ocean water, greater than 26 degrees, evaporation will keep the pressure at the center low. The larger the tropical cyclone, the lower the pressure tends to be at the center.”
The center of a hurricane is where ultra-low pressure develops. It’s so warm that water evaporates quickly off the surface of the ocean. The wind that blows to try to fill in the area of low pressure is warm and has low humidity. That wind picks up moisture from the ocean and spirals up out of a spiraling air mass and dumps massive amounts of water vapor when it reaches the top.
“The rain bands that form are the water vapor that was generated close to the center and then are dropped as rain and form these large convection cells that spiral around that central region,” Dr. Tobin said. “The absolute center of the hurricane, as we all know, is the eye of the hurricane where the weather can actually be calm and clear.”
The eye of the hurricane can be clear because with all the air spiraling around, there has to be some kind of center somewhere. Generally, the eye of the hurricane is just a few miles or tens of miles out of the thousand-mile scale dimension of a large hurricane.
An Unspeakable Tragedy in Louisiana
According to Dr. Tobin, 2005 was the world record hurricane season for the Atlantic Ocean, running out of names at the letter Z and starting the alphabet over. Hurricane Katrina, the most famous, began as a Category 1 hurricane just east of the Florida Keys, rapidly gaining strength as it circled the Gulf of Mexico and eventually reaching Category 5.
“The reason for that was the heat generated by an incredibly strong high temperature zone that was present in the Gulf of Mexico just by bad luck at that particular time of year in that particular year,” he said. “Hurricane Katrina picked up its excess strength and grew into a monstrous storm where near record sea surface temperatures directed it and veered it off towards the north where it went directly at, essentially, New Orleans, or just to the east of New Orleans, as opposed to heading off into Texas like some later hurricanes did.”
Although Katrina initially missed directly hitting the city, an 8-meter storm surge from the east side of the hurricane pushed water up against the coastline. Within hours of the first initial sighs of relief, New Orleans was pummeled with flooding by an oceanic storm surge that overwhelmed the city’s levee defenses.
The levees failed and Katrina eventually claimed more than 1,800 lives and cost an estimated $125 billion in damages.
Oceanography: Exploring Earth’s Final Wilderness is now available to stream on Wondrium.