February 23, 2001, Hour 2: Weather Modification and Control

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Science Friday > Archives > 2001 > February > February 23, 2001:

Hour Two: Weather Modification and Control

"Everybody talks about the weather, but nobody does anything about it." --Mark Twain

It's a standard joke on the evening news. The anchor turns to the weather reporter and says, "Can't you do something about this weather we've been having?"

The answer - perhaps. Since the 1940's, scientists have been looking into ways to modify the weather. Successes have been few, but they may exist. And while the local weatherman definitely can't just order up a nice day for the weekend, it's definitely possible that human actions can affect the weather.

One possibly successful weather modification technique is cloud-seeding. Tiny particles of materials such as silver iodide or dry ice crystals are released from an airplane into a cloud. The particles provide surfaces (sometimes called 'nucleation sites') onto which water vapors can freeze. Then more water freezes onto that water, and so on, until a droplet weighs enough to fall as rain or snow. The technique has been used in the U.S. southwest to attempt to increase rainfall, and by the U.S. military in a 1966 effort known as 'Project Popeye,' aimed at extending the monsoon season along the Ho Chi Minh trail in Vietnam. However, the jury is still out on whether such techniques produce enough extra rainfall to really make a difference. Some experts say that the difference between seeded and non-seeded clouds might be as much as 10 percent -- but it's hard to know for sure.

Tornado near Scottsbluff, Nebraska, 1955.
(Department of Agriculture Weather Bureau image)

Other researchers are investigating whether other types of weather might be modified by short-term human actions. An MIT research group is looking into whether coating a section of the ocean's surface with a one-molecule-thick layer of oil might sap hurricanes of the energy they need to form. A report published in 1999 by Arizona State University researchers says that patterns in rainfall throughout the week on the Eastern coast of the US may be in part due to changing levels of air pollution drifting in from the west. And one researcher is looking into whether zapping tornados with a beam of microwaves might be enough to break up a twister.

Science? Or science fiction? Call in with your questions and comments on weather modification at 1-800-989-8255, and share your opinions online in our Listeners' Lounge (registration required)

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Guests:

Bernard Eastlund
President, Eastlund Scientific Enterprises Corporation
San Diego, California

Kerry Emanuel
Professor of Atmospheric Science
Massachussetts Institute of Technology
Cambridge, Massachusetts

Roelof Bruintjes
Scientist (of Mesoscale and Microscale Meteorology)
National Center for Atmospheric Research
Boulder, Colorado

Charles Doswell
Senior Research Scientist
Cooperative Institute for Mesoscale Meteorological Studies
University of Oklahoma
Norman, Oklahoma

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