How we measure cloud amountĪt any time different types of cloud at different heights above the ground may be visible from an observing station. Cloud type reporting is generally only possible where a human observer is present. The classification is made in terms of the level of the cloud ( high, medium or low) and various cloud genera specified by the cloud form and its features.Ĭommon types of cloud include cumulus, cumulonimbus, stratocumulus and stratus at low levels altocumulus, nimbostratus and altostratus at medium levels and cirrus, cirrocumulus and cirrostratus at high levels. The standard method for classifying clouds is based on the World Meteorological Organisation criteria. To meet these shortcomings cloud base measurements are made from all surface synoptic stations. There is no way of measuring cloud base from space, an element of critical importance for aviation and other purposes.It is often not possible to distinguish between shallow low cloud and fog.Extensive high cloud can mask important features in the distribution of low cloud.This satellite imagery is revealing in many ways, but it has its limitations for the measurement of cloud, in particular: The large scale distribution of cloud is best measured from space in either the visible or infra red part of the spectrum.
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