Search results
Results from the WOW.Com Content Network
Tropospheric clouds form in any of three levels (formerly called étages) based on altitude range above the Earth's surface. The grouping of clouds into levels is commonly done for the purposes of cloud atlases , surface weather observations , [ 7 ] and weather maps . [ 40 ]
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 cloud water path for the liquid and solid (ice) phases of the cloud particles
Cloud chart showing major tropospheric cloud types identified by standard two-letter abbreviations and grouped by altitude and form. See table below for full names and classification. The table that follows is very broad in scope much like the cloud genera template near the bottom of the article and upon which this table is partly based.
Clouds form when the dew point temperature of water is reached in the presence of condensation nuclei in the troposphere. The atmosphere is a dynamic system, and the local conditions of turbulence, uplift, and other parameters give rise to many types of clouds. Various types of cloud occur frequently enough to have been categorized.
Asperitas (formerly known as Undulatus asperatus) is a cloud formation first popularized and proposed as a type of cloud in 2009 by Gavin Pretor-Pinney of the Cloud Appreciation Society. Added to the International Cloud Atlas as a supplementary feature in March 2017, it is the first cloud formation added since cirrus intortus in 1951. [2]
Stratus clouds are low-level clouds characterized by horizontal layering with a uniform base, as opposed to convective or cumuliform clouds formed by rising thermals. The term stratus describes flat, hazy , featureless clouds at low altitudes varying in color from dark gray to nearly white. [ 2 ]
If water droplets form, they can freeze to form ice particles that compose a contrail. [1] Their formation can also be triggered by changes in air pressure in wingtip vortices, or in the air over the entire wing surface. [2] Contrails, and other clouds caused directly by human activity, are called homogenitus. [3]
Recent studies also suggest that cloud formation is sensitive to aerosols – tiny particles in the atmosphere. Aerosols can act as cloud condensation nuclei, around which cloud droplets can form. Changes in aerosol concentrations, due to human activities or natural processes, can therefore influence cloud properties and, consequently, the climate.