Séminaire LATMOS Guyancourt, (ATTENTION changement exceptionnel: salle 2202), jeudi 14 juin, 11h

Andrew Heymsfield (NCAR, Colorado)

Currently, ice production by aircraft is conventionally considered to occur as contrails, which typically form behind jet aircraft as a result of engine combustion when the air temperature is –40°C and below, characteristic of cirrus forming (ice-cloud) conditions. Recent evidence points to the extension of aircraft effects to temperatures where the warmer midlevel clouds are observed. When altocumulus are thin and occur at temperatures between about -10 and -35C, aircraft can produce the peculiar and striking formations called “hole punch” and “canal” clouds, which have the appearance of dissipation trails. I will discuss observations of these features, why they can spread and persist for many hours, and possibly important implications.