Variation in United States cloudiness and sunshine, 1950-82.

Abstract

The variation in cloudiness and percentage of possible sunshine for the contiguous US and six regions thereof is examined, based on data from 101 National Weather Service stations for the years 1950-1982. Over this 33-year interval, linear regression analysis indicates a 3.7% increase in US cloudiness significant at the 1% level, but a nonsignificant (at the 5% level) 0.9% decrease in sunshine. This difference in trend magnitude and significance may be related to an increase in cirrus, perhaps partly aircraft-induced.-from Authors