A comparison of two formula types for calculating long‐wave radiation from the atmosphere

Measurements of long‐wave radiation at Sidney, Montana, indicated that both an analytically derived equation and an empirically derived equation for clear‐sky conditions adequately predict the long‐wave radiation flux at that site for screen level air temperatures above 0°C. However, for air temperatures below 0°C the analytical equation always underestimated the true radiation, while the empirical equation just slightly underestimated it, then match it, and then overestimated it, as air temperature decreased from 0° to −37°C. These discrepancies in the below 0°C temperature regime indicate that the equations may need some modification to conform more closely to reality for low‐temperature conditions.