The Annual and Diurnal Variations of Cloud Amounts and Cloud Types at Six Arizona Cities

Abstract

The annual and diurnal variations of cloud types and cloud amounts are described for six first-order weather stations in .Arizona. These stations are Flagstaff, Winslow, Prescott, Phoenix, Tucson, and Yuma. Most of the data analysed were obtained on punched-cards from the National Weather Records Center at Asheville, North Carolina. The period of record was from January 1, 1948 through December 31, 1955. This information was supplemented by cloud amount data for the period from July 1, 1956 through March 31, 1958 taken from the supplement to the Local Climatological Data for the six stations. After a brief outline of the terrain features in the vicinity of the stations (section II), the type, quantity, and quality of the data are discussed. Emphasis is put on the homogeneity of the records, both temporally at a single station and spatially from one station to another. In section rv the annual variations of cloud amounts, cloud types, and thunderstorms are described, without any reference to the more detailed diurnal variations, which are discussed later, month by month, in section V. Part of the summary (section VI) is devoted to an investigation of the relation between the average cloud cover and the frequencies of occurrence of both clear and overcast skies at a "typical" .Arizona city.