Sky temperatures in the Imperial Valley of California

Abstract

The cloudless sky in the Imperial Valley is shown to have possibilities as a heat sink for cooling livestock and structures. Measurements with a directional radiometer and other instruments indicated that a point in the north sky 60° above the horizon is usually as cool as, or cooler than, other parts of the sky. North sky temperatures averaged 20° to 30° lower than air temperatures near the ground. The correlation of observed sky temperatures with sky temperatures calculated by Brunt's empirical equation from ground observations was 0.58, highly significant.

Section A. Physiology. Cattle in a hot environment

“…The sun roofs should certainly not be too low, because then they act as a shade from part of the cool sky, to which the animals can radiate heat, and provide a hotter surface in its place (Kelly, Bond & Ittner, 1957 a). In work by Kelly, Bond & Ittner (19576) the north sky had a temperature that was 6-9° lower than the temperature of the air near the ground and therefore could act as a 'heat sink'. The temperature and movement of the air were essentially the same in the sun and under a sun roof made of corrugated galvanized steel and painted white on top, but the radiant temperature (measured with a globe thermometer) was much lower under the sun roof than in the sun, 45 compared with 82° (Boren, Smith, Hodges, Larson & Cox, 1961).…”