African Rainfall Up in Smoke.

Scientists led by Daniel Rosenfeld, a professor of meteorology at Hebrew University of Jerusalem, have determined that smoke pollution from agricultural and cooking fires in the tropics of Africa may be contributing to current drought conditions there. Using data gathered by the Tropical Rainfall Measuring Mission satellite, which maps storms in the area using radar and microwave instruments, the researchers found that clouds formed in dirty, particle-filled air produce as little as half the rainfall as same-size clouds formed in clean air. Rosenfeld said in a presentation at the December 2000 meeting of the American Geophysical Union that pollution particles in clouds distribute the water into droplets that are so small that they are very slow to combine into raindrops.