Measurements in low latitude high altitude cirrus

This study has sought to improve knowledge of the properties of ice particle ensembles found in cold ice clouds found in low latitude regions. The following are some main points: • The size distributions are approximately exponential • The PSD slope decreases with temperature but is strongly influenced by transport of condensate from below in the convectively generated ice cloud layers. • The IWCs in the convectively generated ice cloud are one to two orders of magnitude larger than those found in the thin cirrus, presumably formed by weak uplift. • Aircraft icing by highly supercooled, presumably highly concentrated haze droplets was observed. The temperatures were in the -50 to -55°C range. This result may explain earlier observations of aircraft icing in hurricanes at temperatures below the point of homogeneous freezing of activated cloud droplets.