A Survey of Temperature Measurements in Convective Clouds

Abstract

A brief review of errors associated with aircraft measurements of temperature in cumulus clouds is presented. This analysis forms the basis for the introduction of a compilation of in-cloud temperature measurements that the authors deem reliable. The measurements are mostly from radiometric thermometers, along with some carefully selected measurements taken with immersion thermometers. The data were collected in cumuli and cumulonimbi in Russia, the United States, and the central Pacific. An estimate of the in-cloud temperature measurement uncertainty is on the order of 0.5°C. The results suggest that the average temperature excess in cumulus clouds, when averaged over the cloud lifetime, is about 0.2°–0.3°C; this value may be biased to an unknown extent, however, by latencies inherent in identification and aircraft sampling of candidate clouds. The maximum temperature excess in growing cumulus congestus is about 2.5°–4°C. In the weak-echo regions of large thunderstorms, the temperature excess is at least 6°–8°C. The average and maximum temperature excesses in cumulus congestus over land are about 0.5°–1°C greater than over the ocean. Measurements of the spatial and vertical distributions of in-cloud temperature excess are presented. Some measurements that pertain to the structure of in-cloud temperature are also discussed.