Hurricane season starts June 1st and some forecasters think an early season storm is quite possible this year. Bad news with the ongoing oil spill disaster in the Gulf of Mexico. There has been past speculation and theory about an oil slick in the Gulf actually killing or weakening a storm that enters the Gulf. Some have even suggested placing a synthetic oil-like substance over the Gulf to prevent or weaken a hurricane by cutting off evaporation.

Most experts seem to feel the oil slick would not be large enough to cut down on the energy transfer even if the center of a storm crossed over a big slick. Perhaps if a formative low was centered right over a spill site it might have its growth or intensification retarded, but that's about it.  Meanwhile the waves and winds of an active season in the Gulf would mix the oil and water, but also disrupt clean-up and control efforts.  It could also move more of the oil into the "loop current" allowing more to reach the FL Keys and the Gulf Stream to head up the East Coast, albeit in much diluted form presumably. But we really don't have a good idea of what the future holds for the oil spilled or its future interaction with normal currents and Gulf weather or tropical systems.

Oil does indeed calm wind-driven waves (something ancient mariners knew and applied in storms, and something Ben Franklin demonstrated as a parlor trick), thanks to the reduction in surface tension of the water that oil causes. Ripples with a wavelength shorter than 17 mm are affected by surface tension, and these ripples cause a feedback that reduces the height of larger waves with longer wavelengths (Scott, 1986.) The reduction of surface tension also impacts the flow of air above the water, reducing the amount of sea spray thrown into the air, both of which can affect the wind speed. Oil also damps waves by forming a thick viscous film at the top of the water that resists water motion (Scott, 1999.) Oil also helps calm raging seas by switching off of the wind energy needed by the wave to break, because the surface oil film prevents the generation of ripples on the exposed crests of the waves, and this smoother surface makes the wind less able to grab onto the wave and force it to break.

So,  were a hurricane to encounter a large region of oily water would it weaken or even die? A 2005 paper by Barenblatt et al. theorize that spray droplets hurled into the air by a hurricane's violent winds form a layer intermediate between air and sea made up of a cloud of droplets that can be viewed as a "third fluid". The large droplets in the air suppress turbulence in this "third fluid", decrease the frictional drag over the ocean surface, and accelerate the winds. According to this theory of turbulence, oil dumped on the surface of the ocean would reduce the formation of wind-whipped spray droplets, potentially calming the winds. The authors propose spraying oil on the surface of the ocean to reduce the winds of a hurricane. However, the turbulence theory offered by Barenblatt et al. is challenged by other scientists. In a 2005 story in Newscientist magazine, turbulence expect Julian Hunt at University College London, UK, said, "I am very doubtful about this approach." Hunt studies turbulence both theoretically and in the lab, and he  believes that the high wind speeds in a hurricane are not caused by sea spray. In an article for the Journal of Fluid Dynamics, Hunt suggests that variations in the turbulence between different regions of the hurricane cause sharp jumps in wind speed, which are responsible for the hurricane's strongest winds.

Hurricanes are sustained by the heat released when water vapor that has evaporated from warm ocean waters condenses into rain (latent heat). If we can reduce the amount of water evaporating from the ocean, a decrease in the hurricane's strength will result. Oil on the surface of the ocean will act to limit evaporation, and could potentially decrease the strength of a hurricane. However, if the oil is mixed away from the surface by the strong winds of a hurricane, the oil will have a very limited ability to reduce evaporation. According to a 2005 article in Popular Science magazine, Dr. Kerry Emanuel of MIT performed some experiments in 2002 to test if oil on the surface of water could significantly reduce evaporation into a hurricane. He found that the slick quickly dissipated under high wind conditions and rough seas.

A tropical cyclone in its formative stage-- with 40 mph winds or less--might be adversely affected if it encountered the Gulf of Mexico oil slick, due to the reduction of evaporation into the storm. However, a strong tropical storm or full-fledged hurricane would mix the oil into the ocean to such a degree that the storm would probably not see any significant reduction in evaporation.

It remains unknown how the reduction of sea spray by oil might affect a hurricane. If the oil slick expands to a much larger size, there might be a significant reduction in strength of the hurricane, if theory of how a reduction of sea spray will decrease a hurricane's winds is correct. However, the oil slick is currently small in comparison to a hurricane which tends to be Texas-sized, but of course the above and below size of the oil discharge is growing and changing shape all the time. Experts doubt that the oil slick at its current size is large enough to have a significant impact on a hurricane's intensity, but that could change.

The slick started out about 60 miles across, and it would take a hurricane about four hours to traverse the spill at a typical hurricane forward speed of 15 mph. Furthermore, the slick is within 50 miles land, and interactions with land will dominate the behavior of a hurricane that gets that close to the coast. Unfortunately, there is a decent chance that we'll get a real-world opportunity to see what will happen. June tropical storms tend to form in the Gulf of Mexico, and we've been averaging one June storm every two years since 1995. So there's a good chance that a tropical storm or hurricane (or more than one) will interact with the oil spill sometime this season.

Back in the 1960s and '70s, legions of scientists explored technologies to zap strength from hurricanes. Those efforts were scrapped both because experiments were inconclusive and because the cost of deploying a full-scale system to regularly battle the cyclones would have been staggering. Or because of concerns that in lessening winds rain was increased as a trade off causing more flooding (and law suites). In light of Katrina and Rita's $200-billion-plus swath of destruction-and SOME researchers forecasting more violent and catastrophic hurricanes to come, that steep price tag now seems like a bargain, and
scientists are once again entertaining schemes to mitigate monster storms.

One approach, according to veteran hurricane expert Hugh Willoughby, is to create an oily slick on the ocean in the path of an approaching hurricane. Willoughby is a professor at the International Hurricane Research Center in Miami and a former director of the National Oceanic and Atmospheric Administration's Hurricane Research Division. The goal of the oil, he says, is to weaken a storm by preventing seawater from evaporating, a process that fortifies the swirling rain bands that form a hurricane's backbone.

As mentioned earlier, Massachusetts Institute of Technology atmospheric scientist Kerry Emanuel conducted laboratory experiments of the oil concept in 2002, in his tests the slick quickly dissipated under conditions emulating rough seas. "When the winds blow at 100 knots, there really isn't an ocean surface," Willoughby explains. "It goes from water full of bubbles to air full of spray, with a smooth transition between the two." He said the trick would be to formulate a liquid-like substance that clings to the surface of the ocean even during violent winds. "It could be sprayed by a bunch of 100,000-ton tankers."

Another concept involves a squadron of cargo planes airdropping thousands of tons of a water-absorbing powder onto a hurricane to extract moisture from rain clouds. Dyn-O-Mat in Jupiter, Florida, manufactures superabsorbent products, such as garage mats designed to soak up oil from leaky cars. The firm is developing a gel that has shown promise in early trials. In July 2001, Dyn-O-Mat engineers dumped 8,000 pounds of their Dyn-O-Gel (an amount capable of absorbing 4,000 tons of water) over a small thunderstorm near the Florida coast. Within minutes, the storm disappeared from Doppler weather radar. Results like these must be reproduceable many times and by others before being thought conclusive.

In a hurricane, it is thought the result would be two-fold. First, as the clouds dried out, the storm would wither. Then, as superchilled Dyn-O-Gel droplets fell into the ocean beneath a storm, they would further weaken it by cooling the warm water that fuels its growth.

Dyn-O-Mat's founder and CEO, Peter Cordani, has already arranged to lease a specially rigged 747 "supertanker" to conduct trials on actual hurricanes. Meanwhile he has assembled an all-star team of scientists from labs at Florida State University, the National Center for Atmospheric Research, NOAA and elsewhere to begin running computer models that analyze the gel's effect on larger storms. "We already know the gel works," says Cordani, who lost his home during Hurricane Frances. "Now we need to figure out how much to use and where to put it."

Many scientists are skeptical, however. Chris Landsea, a hurricane expert with NOAA, wonders whether hurricanes are simply too big and powerful to respond to human-scale tinkering. "Thunderstorm activity alone could be equivalent to 200 times global electricity production," he points out. "It's just not physically feasible to make an impact." It could be the most concentrated spill at the surface may be too small in relation to the size and energy of a large well developed tropical cyclone.

Time will tell as this unplanned environmental real-world inadvertent "experiment" takes place in the months ahead. The law of unintended consequences may await us. Oh boy.