Observations of Liquid Water in Orographic Clouds over Elk Mountain

Abstract

The relatively simple orographic clouds forming in winter over Elk Mountain, Wyoming provided useful opportunities for field studies of cloud formation and of ice crystal development. In this paper, the observations of cloud droplet populations spanning a range of five consecutive years are summarized. Date are presented which describe the climatology of the cloud droplet spectra. Selected cases are described in detail to illuminate the process at work and to allow comparisons with theoretical predictions. Droplet concentrations are mostly around 300 cm?3 in accordance with the weak updrafts of the clouds and with the mid-continental, unpolluted cloud condensation nucleus concentrations prevailing in the region. In general, the data are in agreement with one-dimensional microphysical model calculations.