Thermal radiation measurements in summer and winter Alaskan climates

Thermal characteristics of the summer and winter Alaskan climates were evaluated by two methods: (1) direct measurement of solar and low‐temperature radiation exchange by means of the panradiometer (an absolute radiation‐measuring device described briefly) and by computation from the measured values, the mean radiant temperature of the environment; and (2) the direct measurement of the mean radiant temperature of the environment with the thermo‐radiometer (which instrument and method of use is also described briefly) and by computation from these measurements, the solar contribution to the total radiation. During the summer period, the solar radiant flux occasionally exceeded 800 kg cal/m 2 hr. The mean radiant temperature of the environment varied from 8°C to 51°C undergoing large and sometimes rapid changes as the intensity of solar radiation varied with sky cover. During the winter period, the solar radiation attained only ten to 30 pet of the summer intensity. The mean radiant temperature varied from −3°C to −55°C and depended strongly on the radiant temperature of the sky, a concept introduced for simplification of the radiation‐exchange problem. The latter temperature was greatly influenced by the water vapor content of the atmosphere.