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Welcome to the Dauntless Aviation Glossary!
At Dauntless, our editorial staff maintains the web's largest unified glossary of aviation terms. This glossary is built from a combination of official, quasi-official,
and proprietary sources (including original material that we develop oursselves). Uniquely, we often provide multiple definitions of a given term so that you can find that which best applies
to you. In order to maximize your learning efficiency, this glossary (and similar ones for our international users) is incresingly fully integrated into our aviation learning apps, including
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Cloud Base
| Cloud Base | | | The cloud base (or the base of the cloud) is the lowest altitude of the visible portion of the cloud. It is traditionally expressed either in m or feet above mean sea level (or planetary surface), or as the corresponding pressure level 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. One method for doing this is as follows: - Find the difference between the surface temperature and the dew point. This value is known as the "spread".
- Divide the spread by 4.4 (if temperatures are in °F) or 2.5 (if temperatures are in °C), then multiply by 1000. This will give you cloud base in feet AGL (Above Ground Level). A shortcut to the above method when temperatures is measured in °C is to simply multiply the spread by 400.
- Add the results from step (2) to the Field Elevation (ft) to get cloud base ASL (Above Sea Level)
| | source: Wikitionary / Wikipedia and Related Sources (Edited) |
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Disclaimer: While this glossary in most cases is likely to be highly accurate and useful, sometimes, for any number of editorial, transcription, technical, and other reasons, it might not be.
Additionally, as somtimes you may have found yourself brought to this page through an automated term matching system, you may find definitions here that do not match the cotext or application in which
you saw the original term. Please use your good judgement when using this resource.
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