The influence of man on climate began to show itself as early as several thousand years ago. In many areas forests gave way to cultivated land, which resulted in an increase in surface wind speed, and some change of temperature and humidity in the lower boundary layer, as well as a change in the regime of soil moisture, evaporation, and river runoff. Another effect of man's activity upon climate is artificial irrigation, which has been applied in arid regions for many centuries. Irrigation appreciably increases evaporation from the earth's surface, causing temperature decrease and an increase in relative humidity. Observations have shown that the effect of forest felling and irrigation on meteorological conditions is limited only to changes in local climate, i.e., the climate of the regions where pertinent measurements are carried out [Landsberg, 1970].