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The cloud height, more commonly known as cloud thickness or depth, is the distance between the cloud base and the cloud top. [1] It is traditionally expressed either in metres or as a pressure difference in hectopascal (hPa, equivalent to millibar ).
The height of the cloud base can be measured using a ceilometer. This device reflects a beam of light off the cloud base and then calculates its distance using either triangulation or travel time. Alternatively, the cloud base can be estimated from surface measurements of air temperature and humidity by calculating the lifted condensation level.
The base-height range for each level varies depending on the latitudinal geographical zone. [7] Each altitude level comprises two or three genus-types differentiated mainly by physical form. [41] [5] The standard levels and genus-types are summarised below in approximate descending order of the altitude at which each is normally based. [42]
The cloud top (or the top of the cloud) is the highest altitude of the visible portion of a cloud. It is traditionally expressed either in metres above the Earth (or planetary) surface, or as the corresponding pressure level in hectopascal (hPa, equivalent to the traditional but now obsolete millibar ).
the cloud height, measured above sea level, ranging from 0 to 20 km; the cloud IR emissivity, with values between 0 and 1, with a global average around 0.7; the effective cloud amount, the cloud amount weighted by the cloud IR emissivity, with a global average of 0.5; the cloud (visible) optical depth varies within a range of 4 and 10.
The height at which the cloud forms depends on the amount of moisture in the thermal that forms the cloud. Humid air will generally result in a lower cloud base. In temperate areas, the base of the cumulus clouds is usually below 550 metres (1,800 ft) above ground level, but it can range up to 2,400 metres (7,900 ft) in altitude. In arid and ...
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The LCL is a good approximation of the height of the cloud base which will be observed on days when air is lifted mechanically from the surface to the cloud base (e.g. due to convergence of airmasses).