National Hail Research Experiment (NHRE)

The National Hail Research Experiment (NHRE) is a scientific field program established to answer the question of whether or not man can modify hailstorms, knowledgably and systematically, to reduce their vast potential for destruction. The National Center for Atmospheric Research (NCAR) is managing the National Hail Research Experiment and, with the aid of an advisory panel of hail experts from the United States and Canada, is providing scientific leadership for the experiment.

It appears that it may be possible, by seeding a developing hailstorm at just the right time and place with a substance such as silver iodide, to convert the storm's moisture into small hail or rain rather than allowing large, dangerous hailstones to grow. The National Hail Research Experiment will attempt to gain detailed knowledge of the internal behavior of hailstorms, through the use of radar, research aircraft, and other tools of atmospheric research, and to evaluate the effect of accurately injecting seeding materials into hailstorm clouds by comparing the behavior of seeded and unseeded storms.

NCAR is managing the National Hail Research Experiment on behalf of its Federal sponsor, the National Science Foundation, which was asked in 1968 by the Interdepartmental Committee on Atmospheric Sciences--a subgroup of the Federal Council on Science and Technology--to sponsor the experiment. Scientists from six universities and the National Oceanic and Atmospheric Administration (NOAA) are participating, and other Federal agencies are providing support. NHRE participants include atmospheric scientists from Colorado State University in Fort Collins and the NOAA Environmental Research Laboratories in Boulder, as well as from some neighboring state institutions such as the University of Wyoming and the South Dakota School of Mines and Technology.

The NHRE field research will be centered around a five-year program of observations and cloud-seeding experiments to be conducted in northeastern Colorado, in the vicinity of the Pawnee National Grassland. During 1971, field research facilities were established near Grover, Colorado, and some new research systems were set up and tested. Although no systematic cloud-seeding experiments were conducted this year, brief seeding tests were performed on July 22 and 28.

During the next five years, beginning with the 1972 hail season, the researchers will use radar, research aircraft, automatic sampling devices, and other techniques to make detailed observations of both seeded and unseedea hailstorms. About 100 scientists and support people are expected to participate in the program. Up to ten research aircraft will gather data and seed the storms, and five radars will probe the interiors of the clouds. Weather balloons will be launched from sites at Grover, Fort Morgan, and Sterling, Colorado, and Kimball, Nebraska. Remote weather stations will record data at 24 locations on the ground, and a network of 425 sampling devices will measure hail and precipitation over the research area.

In conjunction with the hail experiment, NCAR is also sponsoring research on related subjects including public attitudes toward weather modification, environmental implications of cloud seeding, and legal aspects of weather modification. [1]