Scientists' Sense of Snow; March 1995; Scientific American Magazine; by Vames; 1 Page(s)

Seeing the world in a grain of sand may be pass¿. Researchers at the U.S. Department of Agriculture are endeavoring instead to find the future in a grain of snow. By analyzing the size, structure and water content of snowflakes, hydrologists there hope to predict the amount of spring runoff that will be available in areas where snow is a major source of agricultural water.

The approach originated in the USDA¿s Scanning Electron Microscopy Laboratory in Beltsville, Md. In December 1993, when the lab completed the installation of a low-temperature specimen holder, scientists scurried outside to find an insect to image. All they found was a fresh blanket of snow. The investigators collected flakes, dipped them in liquid nitrogen, coated them with a thin layer of platinum and scanned them. The pictures ultimately reached hydrologist Albert Rango and his colleagues, also at the USDA, who envisioned using them to improve estimates of the amount of water held in drifts. "We use microwave data from satellites to determine the area and number of snow grains in a snowpack," Rango notes. "But there is some confusion about the actual water content." The group is sampling snow in the Sierra Nevada Mountains and will combine these data with satellite information.