• Journal of the Korean earth science society
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• v.18 no.6
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• pp.565-578
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• 1997

Clouds are usually formed by adiabatic cooling through ascending currents, radiation cooling or a mixture of warm air and cold one. Ascending currents are caused by covection currents, or they are accompanied with fronts. Thus clouds are formed through various kinds of causes and procedures. So they are various in height and shape. Form of clouds was classified on the basis of the thecriteria that L. Howard proposed in 1803. He distinguished three simple, fundamental classes-Cirrus, Cumulus, Stratus-from which the others were derived by trasition or association. And they are subdivided into 10 genera according to their height and shape. Most of the clouds are subdivided into the detailed kinds to the characteristics such as appearance or intensity of convection current. Sometimes completly different shape of cloud can be developed out of the 'mother-cloud'. In korea, the stratocumulus, altostratus and cirrus clouds frequently appear. Generally we are likely to have rain or snow from the stratus cloud forms(As, St, Sc) and rain shower or hail from the cumulus forms(Ac, Cu, Cb).