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    12-Jun-2025
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Article Images
Background
 
Dew point
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Dew point is the temperature at which saturated air cools to form water vapour (with relative humidity at 100 percent). Should any further cooling occur, condensation will begin to occur forming clouds.

Credits: ESA
 
 
The Foehn wind
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The figure shows what happens when an air parcel with a temperature of 20 degrees centigrade and a relative humidity of 57% is forced to cross a mountain range with an altitude of 2 500 m. The dew point is reached at 900m and clouds are formed. The air is cooled by approximately 1 degree centigrade per 100 metres until the dew point is reached. Above the condensation level the air is cooled at a lapse rate of 0.5 degrees centigrade per 100m. So the temperature of the air at the top of the range will be 3 degrees centigrade.

Credits: ESA
 
  The Jet Stream
 
Jet stream
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The jet stream in the upper atmosphere determines the weather situation in Europe.

Credits: ESA
 


Foehn
Introduction
Exercises
IntroductionPhotos from the planeMeteosat imagesNOAA imagesCloud filmSurface mapsJet StreamInterview with co-pilotSimulation of the
Foehn situation
Find other examples
Links
Satellite images from SareptaMETEOSAT images from EUMETSATSurface mapsInternet Weather sourceNOAAEuropean weather chartsJet StreamForecast Charts for the Jet Stream
Videos
Cloud videoLakes of Albani and Nemi videoPlains of Po river valley and foothills of the Alps videoCloud cover south of Hanover, Germany videoDevelopment of weather systems animationInterview with co-pilotMathematical simulation of foehn
situation, 15-16 March 2000
Eduspace - Download
LEOWorks 3
 
 
 
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