VARIATIONS OF CLOUDINESS, PRECIPITABLE WATER, AND RELATIVE-HUMIDITY OVER THE UNITED-STATES - 1973-1993

Water vapor variables were calculated from radiosonde stations in each of six U.S. regions for which cloudiness observations were available. Associations among variations of cloudiness, precipitable water and r elative humidity during the 1973-93 period over the U.S. as a whole an d in the six regions were determined. Trends in the quantities as well as relations among seasonal variations have been examined. There was a general increase in precipitable water in each season and in each re gion and a suggestion of increases in relative humidity. These were no t accompanied by a general increase in cloudiness that was significant . However, there were significant correlations between seasonal anomal ies of cloudiness and both relative humidity and precipitable water.