Abstract
Simultaneous wind and droplet measurements have been made in three cloudy boundary layers using tethered balloon-borne instrumentation. The types of clouds studied ranged from small thin cumulus to medium cumulus (non precipitating) and stratocumulus formed by the spreading out (shelving) of cumulus. Available synoptic data have been analysed in order to investigate the relative importance of advection and subsidence over scales of order 100 km in the local boundary-layer development. The factors which influenced the extent of cloud cover are also discussed together with the effect of condensation on vertical air motions in the upper half of the boundary layer. Within individual clouds, horizontal variations in droplet spectra were observed to occur over distances of a few metres being related to both position within cloud and height above local cloud base. These results highlight difficulties which may arise in the interpretation of droplet data of horizontal resolution greater than a few metres. Different clouds sampled on the same day showed different amounts of variability in the droplet parameters but no systematic differences between the various case studies were detected.
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Kitchen, M., Leighton, J.R. & Caughey, S.J. Three case studies of shallow convection using a tethered balloon. Boundary-Layer Meteorol 27, 281–308 (1983). https://doi.org/10.1007/BF00125002
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DOI: https://doi.org/10.1007/BF00125002