Hurricane Katrina was a meteorological superstar, famous after flooding New Orleans and wreaking havoc throughout the Gulf Coast region.
What made Katrina so powerful?
Some hypothesize that it could have been an uncommonly powerful storm amid an uncommonly active season, or Mother Nature's payback for years of human pollution.
Todd Miner, Penn State meteorology instructor, said there is no conclusive evidence that human influence has lead to an increase in the severity of hurricanes.
Meteorology professor Jennifer Evans agreed with Miner. There are cycles in hurricane activity; some seasons develop a greater number of more severe hurricanes, Evans said.
And hurricanes as strong as Katrina are nothing new, she added.
Miner said that before people were altering the atmosphere, there were times in the past when hurricane frequency and strength was similar to what is happening this season.
Hurricane Camille, which struck the Gulf Coast region in 1969, was actually stronger than Katrina. Katrina was a Category 3 hurricane when it struck New Orleans; Camille was a Category 5 hurricane, the highest possible category rating, when it struck east of the city.
Camille caused less damage than Katrina because it struck east of New Orleans. Camille was also roughly one-third the size of Katrina, so it affected a much smaller area in general. Because Camille struck in 1969, some argue that there were fewer people with less amenities to damage than when Katrina hit.
Evans said the typical family in 1969 shared one black and white TV, one car and lived in a three-bedroom house with one bathroom. Today many families have multiple vehicles, multiple TVs and multiple computers packed inside modern houses with multiple bathrooms. A popular theory is that Camille did not have the opportunity to destroy as much as Katrina.
As for the connection between the severity of hurricanes and pollution, it is difficult to prove, she added.
Miner said there are industries as well as organizations whose sole existence depends on maintaining the idea that global warming exists and is a problem.
The Atlantic warms as result and nurtures stronger hurricanes, which thrive on warm water. However, this connection has not been proved, Miner said.
Miner said proving the connection between pollution, global warming and a corresponding increase in hurricane strength would require careful analysis of the history of hurricanes in the Atlantic.
"Advanced statistics and longer records are needed to make conclusions as to whether or not hurricanes are becoming stronger," Evans said.
Neither Miner nor Evans believes that a thorough study of hurricanes in the Atlantic has been conducted to draw any conclusions related to global warming.
Additionally, Paul Knight, meteorology instructor and Pennsylvania state climatologist, and Agriculture and Environmental Economics Professor James Shortle, maintain that there is not yet concrete scientific evidence that hurricanes are getting stronger as result of global warming.
Hurricanes are generally born out of a cluster of tropical storms, Miner said. The storms move over warmer water. Hurricanes require roughly 80-degree water to form and water 85 degrees or warmer to become uncommonly strong, Miner said.
The storms collect evaporation from the warmer water and turn it into raindrops. In doing that, heat is generated, Evans said. And heat is the energy that increases wind.
If the wind gets going in the same direction at the same speed, a hurricane forms.
Evans said a hurricane is a group of thunderstorms circling counterclockwise around a hollow center.
Daniel Veren (graduate-meteorology) has experienced two hurricanes. Instead of evacuating, he stayed when Hurricane Ivan struck in 2004 and Hurricane Dennis hit this year. He experienced Ivan, the stronger of the two, in Mobile, Ala.
Veren said it was night, and he was inside a brick house with boarded-up windows. He and buddies passed the night by surveying the storm through a wrought iron screen door and also playing cards and drinking. Outside, the roof of their house sustained damage and trees and power lines fell, Veren said.
"The most eerie thing that I experienced were huge green flashes on the horizon and then realizing that that wasn't lightning but transformers blowing," Veren said.
Veren said he decided to stick around for Ivan because of his interest in hurricanes. He added that what he experienced was nothing like what people had to deal with after Katrina.
Veren said he didn't think Katrina was a direct result of global warming.
"We can't deduce how much human influence there was on the hurricane," Veren said. "The average temperature has been increased, but we can't determine oscillation or if humans are actually increasing the warming.
"It's hard to relate the increase in temperature throughout the year especially to hurricane development," he said. "I'm not saying there isn't a relationship, I'm saying there isn't enough evidence to prove that there is a relationship right now."
