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Immagini dal satellite Svizzera

(copy 3)

[Translate to it:] Satellite images deliver useful information concerning cloud cover as well as cloud type. Usually weather satellites are 'geostationary', which means they look always at the same part of the world, from a height of approximately 36.000 km above ground level.

NOAA satellites are so-called 'polar-orbiting' satellites, travelling at a mean height of approximately 800 km. Usually they cross the same spot 2 times a day delivering high resolution data. As polar-orbiting satellites are only able to look at a smaller region images are sometimes incomplete or stretched at the edges.

Infrared or IR satellite images show cloud cover using the infrared spectral range, which allows a day and night coverage, while visibile images are dark at nighttime. Infrared images are usually coloured in order to emphasize certain structures. The given images show bright red and yellow colours whenever clouds reach the upper part of the troposphere, which is a signal for widespread cirrus clouds or cumulonimbus (thunderstorm) clouds reaching a mature stadium.