Toseemovement in theair youneed two things:
water vapourandcondensationnuclei, tiny
microparticlesonwhichwater droplets form.
Together they form clouds inanunstablestratified
atmosphere (air that becomes colderwith
increasingaltitude). Inmeteorology, thereare10
different cloud typesaccording to theofficial
classificationof theWorldMeteorological
Organisation (WMO). Their various formsshed light
onwinddirection,windspeedand theweather over
the cominghoursanddays.
Thesatellite imagehereshowsabandof cloud
recordedover theNorthSeabetweenDenmark
(bottom right) andNorway,with itsmany fjords.
The cloud formation indicateshighwindspeedsat
analtitudeof several kilometres. Generally
speaking,windspeedand thereforealso the
amount of cloud increaseswithaltitude. Thestrong
windsof the jet streams reachpeakspeedsofup to
540km/hat altitudesof between8,000and18,000
metres.
Movedby thewind
