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'. . , Gul~~() . -9- . III.. METEOROLOGICAL ETUDIES Possible Solar.Effects on Atmospheric Wind Systems The very high atmosphere is primarily under oontrol of the sun. The variable solar emissions oause high atmospheric changes which affect radio communications and even distortions in the earth's magnetic field. At lower levels, the wind systems are essentially controlled by meteorological phe- nomena such as the interplay between oceans and continents or polar regions and the tropics. But what about the transition regions between these levels - to what extent does an interrelationship exist? These are questions which we believe must be answered before accurate long-range weather predictions oan be made. During the past two years, part of the work at the High Altitude Observa- tory has been directed towa~d investigating possible changes in the earth's atmospheric circulation in response to changes in solar activity. A sugges- tive new reeult has been the detection of apparent change in circulation at the "jet stream" level of the atmosphere (about 30,000 ft.), following abrupt increases in solar corpuscular emission. These changes have occurred during the past two winters (1956-57 and 1957-58). The changes begin about three days after the magnetic disturbance, which signals the arrival of a corpus- cular cloud from the sun, and reach a maximum about five or six days later. The resultant wind field pattern produces a strong meridional (north-south) transport of air at relatively frequent intervals in comparison to other years, and, in part at least, may be associated with the breaking of the extended droughts in the southwestern United States. At the same time, research at other institutes throughout the world indicates there may also be an influence on the earth's atmosphere introduced by ohanges in the sun's ultraviolet radiation. Thus, the evidence is mounting that solar changes produce pronounoed effects on the earth's wind systems. In turn, it seems plausible that basic changes in atmospheric circulation may be the cause of extended periods of drought or rain- fall over large areas. But much remains to be done - not just in efforts to understand solar influences, but in understanding the effects of disturbed wind systems ~ such weather elements as rainfall and temperatures. The High AltitUde Observatory believes that a well organized attack should be made on this problem for at least two years. This will require the close coordination of solar and upper-atmospheric physicists with meteorologists.