Miscellaneous

The saturation vapour pressure over liquid water is larger than over ice. This is true for all temperatures where liquid water and ice might coexist. If ice-particles and under-cooled, droplets of liquid water occur next to each other in a mixed-phase cloud or - as in these images - at the inside of an aircraft window, the droplets will evaporate. At the same time the ice-crystals will grow under consumption of the released water vapour.

At the images one can recognize this effect since a clear droplet-free halo

surrounds the ice particles. Only farer away from the ice-crystals the view can be blurred by under-cooled droplets which cover the windows. Here the ice-crystals have forced the droplets in their direct neighbourhood to evaporate. Looking closely at the "cloudy" parts of the window one can also recognize droplets. This phenomenon which is often observed during a flight is a fundamental process for the physics of clouds.

S. Borrmann, flight from Frankfurt to Birmingham, 4:01 p.m., 17 December 2003

Camera Parameters

Olympus E-1 SLR using a 14-54 mm objective. Exposure and sensitivity (400 ASA) were automatically chosen by the camera. The images were taken in the sRGB colour range with a resolution of 2560 x 1920 pixel x 24 colours.

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