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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 convective condensation level (CCL) represents the height (or pressure) where an air parcel becomes saturated when heated from below and lifted adiabatically due to buoyancy. In the atmosphere, assuming a constant water vapor mixing ratio, the dew point temperature (the temperature where the relative humidity is 100%) decreases with ...
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 ).
A ceilometer is a device that uses a laser or other light source to determine the height of a cloud ceiling or cloud base. [1] Ceilometers can also be used to measure the aerosol concentration within the atmosphere. [2] A ceilometer that uses laser light is a type of atmospheric lidar (light detection and ranging) instrument. [3] [4]
The LCL can be either computed or determined graphically using standard thermodynamic diagrams such as the skew-T log-P diagram or the tephigram.Nearly all of these formulations make use of the relationship between the LCL and the dew point, which is the temperature to which an air parcel needs to be cooled isobarically until its RH just reaches 100%.
[6]: 6018–6019 [7] This non-linear response means that a small change in cloud height, hardly observable on radar, would be accompanied by a large change in flash rate. For example, a hardly noticeable 10% increase in cloud height (a measure of storm severity) would have a 60% change in total flash rate, which is easily observed.
The height above the ground or water of the base of the lowest layer of cloud below 6000 meters (20,000 feet) covering more than half the sky. [2] United Kingdom The vertical distance from the elevation of an aerodrome to the lowest part of any cloud visible from the aerodrome which is sufficient to obscure more than half of the sky. [3] United ...
Cloud top height is often much more variable than cloud base elevation. Clouds greatly affect the transfer of radiation in the atmosphere. In the solar spectral domain, cloud albedo is directly related to the nature, size and shape of cloud particles, which themselves are affected by the height of the cloud top.