"a region. Some call these clouds ""high fog"" for the fog-like cloud. While light rain may fall, this cloud does not indicate much meteorological activity. Stratus clouds form when a sheet of warm, moist air lifts off the ground and depressurizes, following the lapse rate. This causes the relative humidity to increase due to the adiabatic cooling. Stratus clouds look like featureless gray to white sheets of cloud. They can be composed of water droplets, supercooled water droplets, or ice crystals depending upon the ambient temperature. Stratus nebulosus clouds appear as a featureless or nebulous veil or layer of stratus"
"at surface level, and the two additional major types above the troposphere. The cumulus genus includes three species that indicate vertical size. Clouds with sufficient vertical extent to occupy more than one altitude level are officially classified as ""low-"" or ""mid-level"" according to the altitude range at which each initially forms. However they are also more informally classified as ""multi-level"" or ""vertical"". The origin of the term ""cloud"" can be found in the old English ""clud"" or ""clod"", meaning a hill or a mass of rock. Around the beginning of the 13th century, the word came to be used as"
"cloud (or word cloud) is one kind of ""weighted list"", as commonly used on geographic maps to represent the relative size of cities in terms of relative typeface size. An early printed example of a weighted list of English keywords was the ""subconscious files"" in Douglas Coupland's ""Microserfs"" (1995). A German appearance occurred in 1992. The specific visual form and common use of the term ""tag cloud"" rose to prominence in the first decade of the 21st century as a widespread feature of early Web 2.0 websites and blogs, used primarily to visualize the frequency distribution of keyword metadata that"
"Etage A cloud étage is a meteorological term used to delimit any one of three main altitude levels in the troposphere where certain cloud types usually form. The term is derived from the French word which means ""floor"" or ""storey"", as in the floor of a multi-storey building. With the exception of the low étage, the altitude range of each level varies according to latitude from Earth's equator to the arctic and antarctic regions at the poles. The high étage ranges from altitudes of in the polar regions, in the temperate regions and in the tropical region. The major high-level"
"vertical extent. These include nimbostratus, towering cumulus congestus, and cumulonimbus. Etage A cloud étage is a meteorological term used to delimit any one of three main altitude levels in the troposphere where certain cloud types usually form. The term is derived from the French word which means ""floor"" or ""storey"", as in the floor of a multi-storey building. With the exception of the low étage, the altitude range of each level varies according to latitude from Earth's equator to the arctic and antarctic regions at the poles. The high étage ranges from altitudes of in the polar regions, in the"
"Cirrus cloud Cirrus (cloud classification symbol: Ci) is a genus of atmospheric cloud generally characterized by thin, wispy strands, giving the type its name from the Latin word ""cirrus"", meaning a ringlet or curling lock of hair. This cloud can form at any altitude between and above sea level. The strands of cloud sometimes appear in tufts of a distinctive form referred to by the common name of ""mares' tails"". From the surface of Earth, cirrus typically appears white, or a light grey in color. It forms when water vapor undergoes deposition at altitudes above in temperate regions and above"
"Cumulus cloud Cumulus clouds are clouds which have flat bases and are often described as ""puffy"", ""cotton-like"" or ""fluffy"" in appearance. Their name derives from the Latin ""cumulo-"", meaning ""heap"" or ""pile"". Cumulus clouds are low-level clouds, generally less than 2,000 m (6,600 ft) in altitude unless they are the more vertical cumulus congestus form. Cumulus clouds may appear by themselves, in lines, or in clusters. Cumulus clouds are often precursors of other types of clouds, such as cumulonimbus, when influenced by weather factors such as instability, moisture, and temperature gradient. Normally, cumulus clouds produce little or no precipitation, but"
"Cloudlet A cloudlet is a mobility-enhanced small-scale cloud datacenter that is located at the edge of the Internet. The main purpose of the cloudlet is supporting resource-intensive and interactive mobile applications by providing powerful computing resources to mobile devices with lower latency. It is a new architectural element that extends today’s cloud computing infrastructure. It represents the middle tier of a 3-tier hierarchy: mobile ""device - cloudlet - cloud"". A cloudlet can be viewed as a ""data center in a box"" whose goal is to ""bring the cloud closer"". The cloudlet term was first coined by M. Satyanarayanan, Victor Bahl,"
"and mesosphere). Nephology is the science of clouds, which is undertaken in the cloud physics branch of meteorology. There are two methods of naming clouds in their respective layers of the atmosphere; Latin and common. Cloud types in the troposphere, the atmospheric layer closest to Earth's surface, have Latin names due to the universal adaptation of Luke Howard's nomenclature. Formally proposed in 1802, it became the basis of a modern international system that divides clouds into five physical ""forms"" that appear in any or all of three altitude ""levels"" (formerly known as ""étages""). These physical types, in approximate ascending order"
"cumulus clouds. Venus, however, does not appear to have cumulus clouds. Cumulus cloud Cumulus clouds are clouds which have flat bases and are often described as ""puffy"", ""cotton-like"" or ""fluffy"" in appearance. Their name derives from the Latin ""cumulo-"", meaning ""heap"" or ""pile"". Cumulus clouds are low-level clouds, generally less than 2,000 m (6,600 ft) in altitude unless they are the more vertical cumulus congestus form. Cumulus clouds may appear by themselves, in lines, or in clusters. Cumulus clouds are often precursors of other types of clouds, such as cumulonimbus, when influenced by weather factors such as instability, moisture, and"
"Cloud In meteorology, a cloud is an aerosol consisting of a visible mass of minute liquid droplets, frozen crystals, or other particles suspended in the atmosphere of a planetary body. Water or various other chemicals may compose the droplets and crystals. On Earth, clouds are formed as a result of saturation of the air when it is cooled to its dew point, or when it gains sufficient moisture (usually in the form of water vapor) from an adjacent source to raise the dew point to the ambient temperature. They are seen in the Earth's homosphere (which includes the troposphere, stratosphere,"
"Pileus (meteorology) A pileus (; Latin for ""cap""), also called scarf cloud or cap cloud, is a small, horizontal, lenticular cloud appearing above a cumulus or cumulonimbus cloud, giving the parent cloud a characteristic ""hoodlike"" appearance. Pilei tend to change shape rapidly. They are formed by strong updraft at lower altitudes, acting upon moist air above, causing the air to cool to its dew point. As such, they are usually indicators of severe weather, and a pileus found atop a cumulus cloud often foreshadows transformation into a cumulonimbus cloud, as it indicates a strong updraft within the cloud. Clouds that"
"They range from a few light years to dozens of light years across. While they are not technically cirrus clouds, the dust clouds are referred to as ""cirrus"" because of their similarity to the clouds on Earth. They also emit infrared radiation, similar to the way cirrus clouds on Earth reflect heat being radiated out into space. Footnotes Bibliography Cirrus cloud Cirrus (cloud classification symbol: Ci) is a genus of atmospheric cloud generally characterized by thin, wispy strands, giving the type its name from the Latin word ""cirrus"", meaning a ringlet or curling lock of hair. This cloud can form"
"Cloud forest A cloud forest, also called a water forest, is a generally tropical or subtropical, evergreen, montane, moist forest characterized by a persistent, frequent or seasonal low-level cloud cover, usually at the canopy level, formally described in the International Cloud Atlas (2017) as silvagenitus. Cloud forests often exhibit an abundance of mosses covering the ground and vegetation, in which case they are also referred to as mossy forests. Mossy forests usually develop on the saddles of mountains, where moisture introduced by settling clouds is more effectively retained. Dependent on local climate, which is affected by the distance to the"
"Cloud height The cloud height, more commonly known as cloud thickness or depth, is the distance between the cloud base and the cloud top. It is traditionally expressed either in metres or as a pressure difference in hectopascal (hPa, equivalent to millibar). Sometimes, the expression ""cloud height"" is used instead of ""cloud base"", in which case the context has to clarify whether the intent is to designate the height of the base of the cloud or the size of it. ""Cloud height"" is not measured directly but is derived from separate measurements of cloud base and cloud top altitudes. Cloud"
"Cloud cover 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. Okta is the usual unit of measurement of the cloud cover. The cloud cover is correlated to the sunshine duration as the least cloudy locales are the sunniest ones while the cloudiest areas are the least sunny places. The global cloud cover averages around 0.68 when analyzing clouds with optical depth larger than 0.1. This value is lower (0.56) when considering clouds with an optical depth larger than 2, and higher when"
"Cloudscape (art) In art, a cloudscape is the depiction of a view of clouds or the sky. Usually, as in the examples seen here, the clouds are depicted as viewed from the earth, often including just enough of a landscape to suggest scale, orientation, weather conditions, and distance (through the application of the technique of aerial perspective). The terms ""cloudscape"" and skyscape are sometimes used interchangeably, although a skyscape does not necessarily include a view of clouds. A highly complex cloudscape—as in some works of J. M. W. Turner, for example—within an otherwise conventional landscape painting, can sometimes seem like"
"vortices along the edge, with twisting masses of scud that may reach to the ground or be accompanied by rising dust. A very low shelf cloud accompanied by these signs is the best indicator that a potentially violent wind squall is approaching. An extreme example of this phenomenon looks almost like a tornado and is known as a gustnado. A roll cloud (""Cloud Atlas"" name "" volutus"") is a low, horizontal, tube-shaped, and relatively rare type of arcus cloud. They differ from shelf clouds by being completely detached from other cloud features. Roll clouds usually appear to be ""rolling"" about"
"Cloud top The cloud top (or the top of the cloud) is the highest altitude of the visible portion of the 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 top is where the snow, rain and sleet come from. Cloud top height can be estimated from the ground by triangulation. However, this is often inconvenient as this is practically feasible only for isolated clouds in full view of (and some horizontal distance away from) the"
"Altocumulus cloud Altocumulus (From Latin ""Altus"", ""high"", ""cumulus"", ""heaped"") is a middle-altitude cloud genus that belongs mainly to the ""stratocumuliform"" physical category characterized by globular masses or rolls in layers or patches, the individual elements being larger and darker than those of cirrocumulus and smaller than those of stratocumulus. However, if the layers become tufted in appearance due to increased airmass instability, then the altocumulus clouds become more purely ""cumuliform"" in structure. Like other cumuliform and stratocumuliform clouds, altocumulus signifies convection. A sheet of partially conjoined altocumulus perlucidus is sometimes found preceding a weakening warm front, where the altostratus is"
"and lesser types. High-level clouds form at altitudes of 5 to 12 kilometers. All cirriform clouds are classified as high-level and therefore constitute a single cloud genus cirrus. Stratiform and stratocumuliform clouds in the high level of the troposphere have the prefix ""cirro-"" added to their names yielding the genera cirrostratus and cirrocumulus. Similar clouds found in the middle level (altitude range 2 to 7 kilometers) carry the prefix ""alto-"" resulting in the genus names altostratus and altocumulus. Low level clouds have no height-related prefixes, so stratiform and stratocumuliform clouds based around 2 kilometres or lower are known simply as"
"a metaphor for rain clouds, because of the similarity in appearance between a mass of rock and cumulus heap cloud. Over time, the metaphoric usage of the word supplanted the old English weolcan, which had been the literal term for clouds in general. Ancient cloud studies were not made in isolation, but were observed in combination with other weather elements and even other natural sciences. In about 340 BC the Greek philosopher Aristotle wrote ""Meteorologica"", a work which represented the sum of knowledge of the time about natural science, including weather and climate. For the first time, precipitation and the"
"Sea of clouds A sea of clouds is an overcast layer of clouds, viewed from above, with a relatively uniform top which shows undulations of very different lengths resembling waves. A sea of fog is formed from stratus clouds or fog and does not show undulations. In both cases, the phenomenon looks very similar to the open ocean. The comparison is even more complete if some mountain peaks rise above the clouds, thus resembling islands. A sea of clouds forms generally in valleys or over seas in very stable air mass conditions such as in a temperature inversion. Humidity can"
"waves. Stratocumulus cloud A stratocumulus cloud belongs to a genus-type of clouds characterized by large dark, rounded masses, usually in groups, lines, or waves, the individual elements being larger than those in altocumulus, and the whole being at a lower height, usually below . Weak convective currents create shallow cloud layers because of drier, stable air above preventing continued vertical development. Vast areas of subtropical and polar oceans are covered with massive sheets of stratocumulus. These may organize into distinctive patterns which are currently under active study. In subtropics, they cover the edges of the horse latitude climatological highs, and"
"clouds: cumulus, stratocumulus, stratus, nimbostratus, and cirrus; as well as nebulae: dark or glowing, amorphus or ring-shaped, and constantly evolving. Cloud (music) In music a cloud is a sound mass consisting of statistical clouds of microsounds and characterized first by the set of elements used in the texture, secondly density, including rhythmic and pitch density. Clouds may include ambiguity of rhythmic foreground and background or rhythmic hierarchy. Examples include: Clouds are created and used often in granular synthesis. Musical clouds exist on the ""meso"" or formal time scale. Clouds allow for the interpenetration of sound masses first described by Edgard"
"Cloud atlas A cloud atlas is a pictorial key (or an atlas) to the nomenclature of clouds. Early cloud atlases were an important element in the training of meteorologists and in weather forecasting, and the author of a 1923 atlas stated that ""increasing use of the air as a means of transportation will require and lead to a detailed knowledge of all the secrets of cloud building."" Throughout the 19th century nomenclatures and classifications of cloud types were developed, followed late in the century by cloud atlases. The first nomenclature (""naming"", also ""numbering"") of clouds in English, by Luke Howard,"
"the cloud itself and ground, while the sky is apparently clear. Serein (meteorology) Serein (; in French) refers to rain falling from a cloudless sky. This sort of rain is said to take on the form of a fine, light drizzle, typically after dusk. The name derives from French ""serein"", meaning ""serene"", or ""clear"" (as in unclouded). An alternative etymology is from Old French ""serain"", evening. An explanation could be the evaporation of the cloud droplets when precipitation drops are formed. Anyway, for others the phenomenon is simply non existing and should be considered equivalent to rain falling from a"
"the clouds include cirrus castellanus, cirrocumulus castellanus, altocumulus castellanus and stratocumulus castellanus. Sometimes cumulus castellanus are referred to, but the type is not recognised by the France's national meteorological service Météo-France, or by the American Meteorological Society and World Meteorological Organisation. Those clouds some would classify as cumulus castellanus typically do not have a common base and are not arranged in a line, thus differing to some extent from the more universally-recognised castellanus types. Some scientists also think that the ""castellanus"" should be a full cloud genus, and not just a cloud species. The Federal Aviation Administration ""implicitly"" considers a"
"Surface layer The surface layer is the layer of a turbulent fluid most affected by interaction with a solid surface or the surface separating a gas and a liquid where the characteristics of the turbulence depend on distance from the interface. Surface layers are characterized by large normal gradients of tangential velocity and large concentration gradients of any substances (temperature, moisture, sediments et cetera) transported to or from the interface. The term boundary layer is used in meteorology and in physical oceanography. The atmospheric surface layer is the lowest part of the atmospheric boundary layer (typically the bottom 10% where"
"Stratocumulus cloud A stratocumulus cloud belongs to a genus-type of clouds characterized by large dark, rounded masses, usually in groups, lines, or waves, the individual elements being larger than those in altocumulus, and the whole being at a lower height, usually below . Weak convective currents create shallow cloud layers because of drier, stable air above preventing continued vertical development. Vast areas of subtropical and polar oceans are covered with massive sheets of stratocumulus. These may organize into distinctive patterns which are currently under active study. In subtropics, they cover the edges of the horse latitude climatological highs, and reduce"
"is not unusual to hear media weather reporters discuss the marine layer as if it were synonymous with the fog or stratus it may contain, but this is erroneous. In fact, a marine layer can exist with virtually no cloudiness of any kind, although it usually does contain some. The marine layer is a medium within which clouds may form under the right conditions; it is not the layers of clouds themselves. Marine layer A marine layer is an air mass which develops over the surface of a large body of water such as the ocean or large lake in"
"Nebula A nebula (Latin for ""cloud"" or ""fog""; pl. nebulae, nebulæ, or nebulas) is an interstellar cloud of dust, hydrogen, helium and other ionized gases. Originally, the term was used to describe any diffuse astronomical object, including galaxies beyond the Milky Way. The Andromeda Galaxy, for instance, was once referred to as the ""Andromeda Nebula"" (and spiral galaxies in general as ""spiral nebulae"") before the true nature of galaxies was confirmed in the early 20th century by Vesto Slipher, Edwin Hubble and others. Most nebulae are of vast size; some are hundreds of light years in diameter. A nebula that"
"could quickly grow to become a cumulonimbus cloud and continue to grow into a cumulonimbus incus cloud. Pileus (meteorology) A pileus (; Latin for ""cap""), also called scarf cloud or cap cloud, is a small, horizontal, lenticular cloud appearing above a cumulus or cumulonimbus cloud, giving the parent cloud a characteristic ""hoodlike"" appearance. Pilei tend to change shape rapidly. They are formed by strong updraft at lower altitudes, acting upon moist air above, causing the air to cool to its dew point. As such, they are usually indicators of severe weather, and a pileus found atop a cumulus cloud often"