Radon 222 concentrations in the convective patterns of a mountain environment

Radon 222 concentrations have been measured in a mountain environment to learn more about radon 222 distribution and to test its usefulness in the study of certain features of convective cloud systems over a mountain range. Theoretical considerations make the use of radon 222 rather than its daughter products necessary in tracer applications of this kind. When the atmosphere is in a quiescent state, as generally occurs in the early morning hours, aircraft sampling gives radon concentrations varying from 0.43 pc/liter at 40 meters over a basin near the mountain ridge to 0.004 pc/liter at altitudes of nearly 8 km (MSL). The distribution over a mountain ridge follows that of potential temperature. Mountain slope heating is an important mechanism in the transport of air rich in radon 222 from the canyons and basins near the mountain to higher levels as solar heating progresses during the morning hours. Turbulence created by lee waves is another mechanism responsible for carrying radon 222 aloft. The first cumulus humilis clouds formed in the clear air above the mountains have a radon content in excess of their environment of approximately 25%. This appears to be supplied by air having a high radon content in updrafts below the cloud. Cumulus congestus exhibit patterns of activity that suggest an increase in radon flux into the cloud base over that found in the initial cloud development. Full-scale cumulonimbus systems may have an estimated total radon 222 content of the order of 1.5 curies in a volume of about 50 km3.