Cloud cover (also known as cloudiness, cloudage or cloud amount) refers to the fraction of the sky obscured by clouds when observed from a particular location. The sky is the part of the Atmosphere or of Outer space visible from the surface of any Astronomical object. A cloud is a visible mass of droplets or frozen crystals floating in the atmosphere above the surface of the Earth or another Planetary body
Contents |
Measurement
Traditionally, cloud cover is estimated by trained observers from a meteorological station on the ground and expressed either in oktas (or eighths of the sky) or in tenths. Meteorology (from Greek grc μετέωρος metéōros, "high in the sky" and grc -λογία -logia) is the Interdisciplinary OKTA is the only Oil refinery in the Republic of Macedonia. It is situated outside the capital city of Skopje. These visual estimates are given to the closest value only. A value of 0 refers to clear sky, while 8 oktas or 10 on the decimal scale indicates overcast. Such estimates are representative of conditions within the range of visibility of the observer. In Meteorology, visibility is a measure of the Distance at which an object or light can be clearly discerned The main problems associated with this method include the inability of making observations when visibility is very low (e. g. , in case of fog) or the difficulties of estimating the correct fractional cover for clouds that are near the visual horizon.
With the advent of satellite observations, it has become possible to estimate the fractional cloud cover much more accurately (though not without difficulties). Earth observation satellites are Satellites specifically designed to observe Earth from Orbit, similar to Reconnaissance satellites but intended Identifying deep bright clouds on satellite images acquired in the solar spectrum is relatively easy. Satellite imagery consists of photographs of Earth or other planets made by means of Artificial satellites. However, thin clouds or clouds with horizontal dimensions smaller than the spatial resolution of the sensor may largely escape detection.
Role in the climate system
Clouds play multiple critical roles in the climate system. Climate encompasses the temperatures humidity rainfall atmospheric particle count and numerous other meteorogical factors in a given region over long periods of In particular, being bright objects in the visible part of the solar spectrum, they efficiently reflect light to space and thus contribute to the cooling of the planet. The Sun (Sol is the Star at the center of the Solar System. A spectrum (plural spectra or spectrums) is a condition that is not limited to a specific set of values but can vary infinitely within a continuum. A small increase in cloud cover could, in principle, balance the heating resulting from greenhouse gases (though this may have other implications as well). Greenhouse gases are gaseous constituents of the atmosphere bothnatural and anthropogenic that absorb and emit radiation at specific wavelengths within the spectrum of thermal infrared
See climate change for a more detailed discussion of these issues. Climate change is any long-term significant change in the “average weather” that a given region experiences
References
- Huschke, Ralph E. (1959) Glossary of Meteorology, American Meteorological Society, Boston, Second printing-1970.
- McIntosh, D. H. (1972) Meteorological Glossary, Her Majesty's Stationery Office, Met. O. 842, A. P. 897, 319 p.
- IPCC Third Assessment Report, has extensive coverage of cloud-climate interactions: See, in particular, chapter 7. 2.
External links
- Glossary of Atmospheric Terms, http://www.nsdl.arm.gov/Library/glossary.shtml#Cloud_cover : From the National Science Digital Library's Atmospheric Visualization Collection.
Dapyx Software network: MP3 Explorer | Ebook Manager | Zenithic