Daily patterns of dew-point temperature in a semiarid climate

Hourly values of dew-point temperature (Tdp) recorded at ICRISAT, India, were examined on selected days between 1981 and 1985. The diurnal pattern changed seasonally, with a decrease in the mean Tdp during the dry season. Day-to-day variations of the mean Tdp and amplitude were large but, in general, values tended to remain fairly constant through the night, and started to decrease 1–2 h after sunrise to a minimum at 15:00–16:00 h. This pattern was simulated with a cosine function using two spot readings of humidity (at 07:15 and 14:15 h) from the meteorological site. The simulation gave reasonable agreement with measured values on days with widely contrasting patterns of Tdp