Answers archive: Attempts to weaken, destroy hurricanes Q: Could a large chunk of ice from the poles be towed into the path of a hurricane to weaken it? A: As with most hurricane modification ideas, this one is much easier said than done. Part of the problem is the sheer size of a typical hurricane and the amount of ocean that one traverses in a day. A hurricane with a 30-mile diameter eye, moving at 10 mph, will cover a swath of 7,200 square miles in one day. That would be a lot of ice! And this assumes we know exactly where to place the ice. Quite often the uncertainty in the path of a hurricane can be 100 miles in a 24-hour forecast. Learn more about weather modification on our USA TODAY resource page. (Answered by Bob Swanson, USA TODAY's assistant weather editor, September 27, 2005) Q: Could dry ice be dropped into a hurricane to weaken it? A: The U.S. government has attempted to modify hurricanes by dropping dry ice and silver iodide into them (Project Cirrus in the late 1940s and early 1950s and Project Stormfury in the 1960s and 70s. Results of the studies were inconclusive. Even if proven effective, there seems to be no practical way to decide when, where and which storms to attack with modifying substances. There have been attempts by the government to modify hurricanes by dropping dry ice and silver iodide into them (Projects Cirrus and Stormfury). Results of the studies were inconclusive. Even if proven effective, there seems to be no practical way to decide when, where, and which storms to attack with modifying substances Considering that the vast majority of tropical waves that come from the African continent, it is impossible to try to modify every one of them. While most never develop into tropical systems that impact the U.S. mainland, it is hard to foresee which storms will develop considering the many atmospheric variables are involved.



It would seem that a more logical course, while the search for effective modification techniques continues, would be to further improve forecast accuracy of tropical systems as well as evacuation techniques of hurricane-prone areas. The Atlantic Oceanographic and Meteorological Laboratory makes a persuasive case about improving forecasts and limiting coastal development. There is plenty more about weather modification on our USA TODAY resource page. (Answered by Bob Swanson, USA TODAY's assistant weather editor, September 5, 2005) Q: Why don't they destroy or weaken hurricanes when they threaten land? A: The basic problem is the size and intensity of hurricanes. They cover tens of thousands of square miles even when they are just beginning. They draw their energy from air over hundreds of thousands of square miles of ocean. Cooling the water over this large area or finding a way to prevent evaporation of water would reduce hurricanes' strength. But, all of the dry ice in the world would be quickly absorbed in a small part of the ocean near a hurricane. Also, the hurricane would quickly move away from the cooled water or water covered with something to prevent evaporation. The National Hurricane Center notes that a hurricane releases heat energy at a rate of 50 trillion to 200 trillion watts. (trillion here is used in the U.S. and French sense: a number followed by 12 zeros) This is the equivalent of a 10-megaton nuclear bomb exploding about every 20 minutes. Q: I saw a report on television about someone who had a substance that could be dropped into clouds and absorb water. They did an experiment where they dropped some on clouds off Florida and the clouds dissipated. The television reporter said this could be used to weaken hurricanes. Why isn't this done? A: I've seen this report a couple of times, and both times I've been tempted to call the TV reporters and producers involved and offer them a good deal on a bridge in Brooklyn, N.Y. All reporters can't be expected to know a lot about everything they report, but they do owe it to their readers and viewers to find out what they don't know. A phone call to someone who knows about hurricanes, could have shown the problems with this idea. The best discussion I've seen on this is in the FAQ on hurricanes on the NOAA Hurricane Research division Web site. If you go to the HRD's answer to this question, you'll see the idea has several problems, beginning with the claim that it caused clouds to dissipate. When I saw this I recalled something that a scientist who studies clouds told me several years ago, "You can make clouds go away by watching them." In other words, small cumulus clouds like those used in the "experiment' normally don't last very long. On a day when some of them will grow into thunderstorms, it's impossible to select the one that will grow since most of the clouds will quickly go away. Q: Wouldn't a huge bomb weaken a hurricane? If they are worried about radioactivity, they could use powerful fuel-oil bombs. A: A bomb or bombs would be a dead end since the amount of energy a hurricane is releasing and the size of its circulation would make any bomb, including the largest nuclear bomb, seem more futile than trying to stop a charging elephant by throwing a ping-pong ball at it. As noted above, hurricanes release tremendous amounts of heat energy. In fact, since hurricanes are "heat engines" that depend on the temperature contrast between warmth at the ocean surface and cold air aloft, we could wonder whether the heat from any kind of bomb would actually add to the storm's natural heat supply, making the storm stronger. Trying to heat the upper atmosphere with bombs, to lessen the heat contrast, would be like trying to heat the city of Minneapolis in January by opening the windows of a house. Until recent years, many people suggested using nuclear bombs. But, doing that would create a hurricane with the danger of radioactivity as well as wind and storm surge. Q: Since ocean heat is a source of hurricane energy, why not cool the ocean with icebergs or dry ice? A: Again, the amount of heat involved is the problem. Transporting enough ice burgs or dry ice to cool thousands of square miles of tropical ocean would be extremely expensive. Plus, there is no way to know where a storm is likely to form or go after it forms more than a few days ahead. This means getting the ice to the right place would be a huge problem. Q: What happened to the idea of seeding hurricanes to weaken them? A: During the 1960s the U.S. Navy and the National Oceanic and Atmospheric Administration (NOAA) tried a more sophisticated way of making hurricanes weaker. This research was known as Project Stormfury. The basic idea was to seed clouds just outside the eye wall with silver iodide. The silver iodide, which is widely used in cloud seeding, encourages supercooled water - water that's colder than 32 degrees F but is liquid, not ice - to freeze. This releases latent heat, which would make the clouds grow, stealing some of the humid air that's helping the eye wall clouds grow and create strong winds. This seemed to work with Hurricane Beulah in 1963 and Hurricane Debbie in 1969. But, scientists had no way of knowing whether these two storms would have weakened any way at that time. Hurricanes often weaken and then regain strength naturally. Also, since the 1980s researchers have found that most hurricanes don't have enough supercooled water for seeding to work. Concerns were also raised that the experiments could make a storm change course, hitting some place that it otherwise wouldn't. The experiments did increase hurricane knowledge and also led to the purchase of the two WP-3 airplanes that NOAA still uses for hurricane research and tracking. Bob Sheets, the retired director of the National Hurricane Center, and I have an entire chapter on Project Stormfury in our book, Hurricane Watch: Forecasting the Deadliest Storms on Earth. Bob was the last director of Stormfury. Q: Why not attack a storm when it's still only a weak tropical wave or depression? A: About 100 waves or disturbances form in the Atlantic Basin each year, but only five become hurricanes in a typical year. There's no telling which will grow until they have started growing. Also, even a disturbance that's releasing only 10% as much energy as a hurricane is still releasing a lot of energy. Q: Since hurricanes draw their power from the latent heat released as the water vapor in humid air condenses, why not find a way to cut off the supply of humid air? That is, why not reduce the evaporation of water from the parts of tropical oceans that are supply the humid air a storm needs? A: Since latent heat is the main source of the energy needed to run a hurricane, some researchers have attempted to develop liquids that could be spread over the ocean to limit evaporation. Even if such a liquid is ever developed, using it could raise serious concerns about environmental dangers. What would it do to life in the sea? Could it affect the weather in unintended ways? Since most of the rain that falls on land comes from water that evaporates over the oceans, could such an attempt to weaken hurricanes affect global rainfall? What would such a liquid be like if it washes up on beaches in the Caribbean? Q: Is trying to modify hurricanes such a good idea after all? A: Today, scientists are more cautious about trying to modify the weather than they were during the 1960s. Hurricanes, along with other storms and ocean currents, help balance the Earth's heat budget. Trying to change hurricanes could have consequences that no one intended.