(press release). This article from 2000 describes how scientists use data from satellites and rain gauges along with tree-rings and lakebed sediments to understand and predict drought in North America.">


back Physical Processes that Cause Drought


Sea surface temperatures in the equatorial Pacific affect precipitation (and therefore plant growth) over much of the North American continent. When there is warmer than normal water (dark red) in the Pacific, more rain than normal often falls over western and central North America (green indicates above average plant growth, generally the result of extra rain). Conversely, cold water temperatures in the Pacific (dark blue) lead to decreased rain over western North America (brown indicates a relative lack of plant growth). (Animation courtesy Sietse Los and Marit Jentoft-Nilsen, NASA GSFC)