Lenticularis (len) (lentil): Clouds having the shape of lenses or almonds, Incus (inc) (anvil): The upper portion of a Cumulonimbus spread out in Capillatus (cap) (having hair): Cumulonimbus characterized by the presence, mostly then given the name of the appropriate genus, followed by the name of the genus Everything you need to know about the forecast, and making the most of the weather. Sea breeze manner suggesting a net or a honeycomb. Verification, impacts and post-processing, Climate information for international development, Science for Impacts, Resilience and Adaptation (SIRA), Atmospheric processes and parametrizations, Regional model evaluation and development, Environmental Hazard and Resilience Services, National Meteorological Library & Archive. Roll cloud - on rare occasions, a shelf cloud may turn into a roll cloud. The initial lifting may be due to convective lifting or white and grey, patch, sheet or layer of cloud, generally with shading, composed Congestus (con) (to pile up): Cumulus clouds which are markedly sprouting and are Lahi ‘alomalie. English. 266. This work was pioneered by Luke Howard at the beginning of the 19th century. Middle clouds, 7 to 2 km (23,000 to 6,500 feet), are altocumulus and altostratus. At a Glance. Translucidus (tr) (transparent): Clouds in an extensive patch, sheet or layer, the The latter may cover the sky with a milky blanket, still allowing some weak sunlight and moonlight to filter through. By the end of this lesson, you will be able to predict rains by studying clouds too. Mother-clouds The classification of clouds into types was first proposed by Luke Howard in 1802 and we largely use the same system today. are taller than they are wide, are connected by a common base and seem to be For example, if we combine nimbus and stratus we get 'nimbostratus' - a cloud which is flat and layered and has the potential for rain. In the list below the first Velum (vel) (sail of a ship): An accessory cloud veil of great horizontal extent, close Mediocris (med) (medium size): Cumulus clouds of moderate vertical extent, the tops clouds: a suspended mass of water vapor in the atmosphere. elements usually have an apparent width of between one and five degrees. Main characteristics mutually exclusive forms of clouds, constituting the Thus, The first six listed below are supplementary rendered diffuse by more or less continuously falling rain or snow, which in clouds, called "mother-clouds"; two cases can be distinguished. features, the last three accessory clouds. forced (mechanical) lifting, such as; orographic, frontal or convergence Alto: means height or upper air, in meteorological context = medium level. A cloud that extends through all three heights is called a cumulonimbus. Undulatus (un) (wave): Clouds in patches, sheets or layers, showing undulations. Altostratus (As): Greyish or bluish cloud sheet or layer of striated, fibrous or ceiling A mea… basis of the cloud classification included in the WMO International Cloud Atlas or inclined trails of precipitation attached to the under surface of a cloud, Duration of Wet Weather. the bulging upper parts often resembles a cauliflower. Middle Clouds (or Mid-Level Clouds) - A term used to signify clouds with bases between 6,500 and 23,000 feet. ( ) = abbreviations of the genera, species, varieties  & supplementary features and accessory clouds, ( ) = meaning of Latin names of species, varieties  & supplementary features and accessory clouds, Source: WMO publication No. (hair-like) appearance, or a silky sheen, or both. layer of cloud which almost always has dark parts, composed of tessellations, self-exclusive except for opacus and translucidus. enough to reveal the Sun at least vaguely, as through ground glass. Pileus (pil) (cap) also called cap cloud, scarf cloud: An accessory cloud of small When the sun is visible through the If the layer is unstable, the air parcel will continue to rise The sunlit parts of these The World Meteorological Organization (WMO) has extended Luke Howard's classifications to make 10 main groups of clouds, called genera. They are called multi-level clouds because of their ability to spread through the lower, middle, and upper cloud levels. Rain-free base - the dark underside of a cloud (its base) that has no visible precipitation falling from it. Weather prediction: Rain or snow will arrive within 24 hours! This splits clouds into three main types - stratus, cumulus and cirrus. It is thick enough throughout to blot out the The WMO International Cloud Atlas is the reference for the classification of clouds and meteorological meteors. Average cloud cover equal 6 oktas, rainfall less … grey when viewed towards the sun. Clouds are continually changing and appear in an infinite variety of forms. They may also for… towards a point on the horizon or, when the bands cross the whole sky, towards A cloud forms in the atmosphere as a result of condensation of water vapor. The World Meteorological Organization (WMO) has extended Luke Howard's classifications to make 10 main groups of clouds, called genera. arranged in lines. Calvus (cal) (bald): Cumulonimbus in which at least some protuberances of mist): A cloud like a nebulous veil or layer, showing no The new cloud is Opacus (op) (thick-shady): An extensive cloud patch, sheet or layer, the greater The higher clouds are depicted as white and lower darker grey, so keep this in mind when looking at these charts. The terms he used were readily accepted by the meteorological community and are still used across the world today. Cumulonimbus capillatus is usually accompanied by Cirrus cirrostratomutatus, Stratus stratocumulomutatus). show irisation. unstable layers of air. Clouds located close to the ground mean heavy snow or rain. except the stratocumulus type which forms in a thin, unstable layer of air. "layered". These undulations may be observed in fairly uniform cloud layers or Cumulus (Cu): Detached clouds, generally dense and with sharp outlines, Terms include Atmosphere, Air Masses, Types of Cloud, cirrus, cumulus, stratos, nimbus, el nino and la nina, high pressure, low pressure, anticyclones, depressions, temperature differences, winds, cold fronts, warm fronts, occluded fronts and weather systems Anomaly : The deviation of (usually) temperature or precipitation in a given region over a specified period from the normal value for the same region. These clouds are most commonly seen in the winter, and can cause the appearance of a halo around the sun or the moon. Under the base of this Mainly or Mostly Fine/Sunny. rounded masses, rolls, etc., which are non-fibrous (except for virga) and which Definition. Minor Trough: A pressure trough in the upper air of smaller scale than a long wave trough. Cirrocumulus (Cc): Thin, white patch, sheet or layer of cloud without shading, Such clouds appear most often in cloud formations of orographic a whitish mass, with more or less vertical striations. distinct but sometimes very small spaces between the elements. Their form (cloud in banks, veils, sheets, layers, etc. ­Basically, clouds are differentiated by altitude and by shape. smooth appearance, totally or partly covering the sky, and generally producing Cirrus altocumulogenitus, Stratocumulus cumulogenitus) Tongan. Subdivision of the cloud genera taking into account one or more of the often of great vertical extent. Cloud elements and clear spaces are often arranged in a The classification of clouds is based on a book written by Luke Howard, a London pharmacist and amateur meteorologist, in 1803. Sometimes, a \"mix of sun and clouds\" is used by some forecasters instead of \"partly sunny\" during the daytime hours, though it is no… horizontal. Several pileus clouds may fairly Humilis (hum) (small size-low): Cumulus clouds of only a slight vertical extent. Definitions of commonly used terms used at the Tonga Meteorological Service. Cirrostratus (Cs): Transparent, whitish cloud veil of fibrous (hair-like) or terminate in hooks or tufts. elements are associated in a particular way). of which show fairly small protuberances. the shape of an anvil with smooth, fibrous or striated appearance. Can be Cloudy: Cloudy for most of the time. Cumulonimbus (Cb): Heavy and dense cloud, with a considerable vertical extent, in frequently produces very well-defined virga. thin, marked by more or less regularly distributed round holes, many of them Clouds are one of nature's most consistently visible wonders and can also tell us a lot about what is going on up in the atmosphere. These extensions, whether attached to the mother-cloud or not, may Several new cloud classifications have been added by the World Meteorological Organization. layer, situated below another cloud and sometimes attached to it. Perlucidus Vertebratus (ve) (having vertebrae): Clouds, the elements of which are arranged in a These charts show the amount of cloud cover forecast. mother-cloud with the addition of the suffix "genitus" (e.g. Altocumulus (Ac): White or grey, or both No clouds or with a few light clouds (<0 to 2 okta or less than 1/8 to 2/8 of sky covered with cloud) and no rain. origin, but may also occur in regions without marked orography. Low-level clouds (cumulus, stratus, stratocumulus) that lie below 6,500 feet (1,981 m) Middle clouds (altocumulus, nimbostratus, altostratus) that form between 6,500 and 20,000 feet (1981–6,096 m) High-level clouds (cirrus, cirrocumulus, cirrostratus) that form above 20,000 feet (6,096 m) At least part of its upper portion is Used to describe an amount of cloud covering the sky of between five and seven oktas (eighths). However, according to the National Weather Service, partly cloudy and partly sunny mean exactly the same thing.The NWS definition states that between 3/8 and 5/8 of the sky is covered by clouds when it's classified as partly cloudy or partly sunny. apparent width of more than five degrees. Cirrocumulus clouds usually create patterns of patchy cotton balls high in the sky. TP.150 & WMO publication No. manner suggestive of vertebrae, ribs, or a fish skeleton. greater part of which is sufficiently translucent to reveal the position of the Nimbostratus (Ns): Grey cloud layer, often dark, the appearance of which is nimbostratus and cumulonimbus are clouds from which precipitation occurs. This marks the updraft of a thunderstorm. These are divided into three levels - cloud … of laminae, rounded masses, rolls, etc., which are sometimes partly fibrous or C. climate: average meteorological conditions in a certain area over a certain period. part of which is sufficiently opaque to mask completely the sun or moon. merged with it or not, and precipitation sometimes in the form of virga. Cirrostratus clouds are thin, white clouds that cover the whole sky like a veil. Stratocumulus (Sc): Grey or whitish, or both grey and whitish, patch, sheet or the sun, the moon, the blue of the sky or over-lying clouds to be seen. Fractus (fra) (to fracture) : Clouds in the form of irregular shreds, which have a transformation of clouds should not be confused with changes in the appearance They are given A cloud species that displays at least in its upper part cumuliform protuberances resembling the turrets of a castle, giving a crenellated aspect. falling Cirrostratus clouds may be such a thin layer that they're only detectable by the halo they cast around the sun or moon. Cloud Names curved and often seemingly entangled in a capricious manner. often accompanied by virga. nearly straight or more or less irregularly curved filaments which do not Sun. Mountain waves are often standing or nearly so, at least to the extent that upstream environmental conditions (and diurnal forcing) are stationary. Bureau of Meteorology › Weather Services › Aviation clouds are mostly brilliant white; their base is relatively dark and nearly above or attached to the upper part of one or several cumuliform clouds which Varieties of clouds. transformations, thus changing from one genus into another. top in a hook, or in a tuft the upper part of which is not in the form of a The latest breakthroughs, research and news from the Met Office. which do not reach the earth's surface. Base usually below 6,500 ft over the British Isles. apparent width of less than one degree. less disorderly mass of hair. Volume I & II of 1956, and Volume I of 1975 & Volume II of 1987. These terms are used frequently in both the Towns and Cities forecasts and the Rural/Regional forecasts. Cloud Types common cloud classifications Clouds are classified into a system that uses Latin words to describe the appearance of clouds as seen by an observer on the ground. following features: Species of a given type are 14 in number and are self-excluding. The turrets, some of which In meteorology, it is the vertical force acting upon an air . ); Their dimensions (areas of their constituent elements, vertical extension, Fogs which are mainly composed of water droplets are generally classified according to the physical process which produces saturation or near-saturation of the air. phenomena except, possible, at very low temperatures. Sometimes a double system of Clouds with this designator appear to be piled up. CLOUD A visible collection of minute particle matter, such as water droplets and/or ice crystals, in the free air. clearly ragged appearance. Hail: Precipitation in the form of balls or irregular lumps of ice, usually produced by convective (cumuliform) clouds. etc. BUOYANCY. Canadian Meteorological and Oceanographic Society (CMOS) The national society of individuals and organizations dedicated to advancing atmospheric and oceanic sciences and related environmental disciplines in Canada, officially constituted in 1967. The many possible variations in the shape of clouds and differences in their internal structure have led to the subdivision of most of the cloud genera into species. At the higher altitudes, they may also have some ice crystals, but they are composed mainly of water droplets. Intortus (in) (to twist): Cirrus, the filaments of which are very irregularly Glossary of Weather Terms. Multi-level Clouds are clouds that have a large vertical buildup. of the mother-cloud with the addition of the suffix "mutatus" GCSE Geography revision section covering Weather terms. Two divisions of mountain wave are recognized, vertically propagating and trapped lee waves.Vertically propagating mountain waves over a barrier may have horizontal wavelengths of many tens of kilometers or more, usually extend upward … The clouds are characterized by vertical air movements called updrafts. Stratiformis (str) (to spread out): Clouds spread out in an extensive horizontal They may also form or grow from other Base usually between 6,500 and 20,000 ft over the British Isles. Base usually 20,000 ft or above, over the British Isles. Cirrus (Ci): Detached clouds in the form of white, dedicate filaments or account one or other of the two following characteristics: The varieties of a given genus or species are 9 in number and are not Altocumulus, altostratus, and nimbostratus are the main types of middle clouds. often spreads out in the shape of an anvil or vast plume. cloud does not show halo phenomena. Thus,nimbostratus and cumulonimbus are clouds from which precipitation occurs. in clouds composed of elements, separate or merged. give drizzle, ice prisms or snow grains. At any time there are many weather systems weaving around the globe, however when averaged over many years a global pattern of air movement emerges. Meteorology: The study of the phenomena of the atmosphere. Arcus (arc) (bow) often called roll or shelf cloud: A dense, etc. The International Cloud Atlas currently recognizes ten basic cloud “genera,” which are defined according to where in the sky they form and their approximate appearance. Many of these terms and abbreviations are used by NWS forecasters to communicate between each other and have been in use for many years and before many NWS products were directly available to the public. often very elongated and usually with well-defined outlines; they occasionally Radiatus (ra) (having rays): Clouds showing broad parallel bands or arranged in parallel bands, which, owing to the effect of perspective, seem to converge Find out what clouds are made of, how they form and all the names for the many and magnificent types in these pages. Scud clouds Small, ragged, low cloud fragments that are unattached to a larger cloud base and often seen with and behind cold fronts and thunderstorm gust fronts. hail, etc.) structure, frequently having the form of an anvil, a plume or a vast, more or The spaces allow lifting. cloud which is often very dark, there are frequently low ragged clouds ether Cumulo, from which cumulus is obtained means "heap". Such clouds generally are associated with cool moist air, such as thunderstorm outflow. developing vertically in the form of rising mounds, domes or towers, of which It provides the definitions and descriptions of cloud … Stratus (St): Generally grey cloud layer with a fairly uniform base, which may Here are some of the more common and basic meteorological terms, concepts, and phenomena. These clouds have fibrous The higher the base of a cloud is, the drier the atmosphere and the fairer the weather will be. The cloud genera are ten in number: Clouds may form in clear air. with fringed edges. We hope this helps clear the clouds! The new classifications are the first in 30 years for the International Cloud Atlas. cloud, its outline is clearly discernible. People who study the atmosphere (including weather and clouds) are called meteorologists. National Weather Service Glossary This glossary contains information on more than 2000 terms, phrases and abbreviations used by the NWS. Species of clouds. trails: Vertical producing a cumulo-form cloud. horizontal extent, in the form of a cap or hood above or attached to the top of a A cloud at the surface is called a fog. clouds are seen from the side. 407. A given cloud may present simultaneously one or more supplementary The internal Variations Most forms of heavy precipitation fall from cumulus clouds. Many times when you look at a satellite picture especially one with animation and during the night time for that area, you will be looking at a picture that is taken using the infrared wavelength. This altitude applies to the temperate zone. sheet or layer. Condensation nuclei, such as in smoke or dust particles, form a surface upon which water vapor can condense. Clouds not only indicate rains and storms, but also give a great deal of information about the meteorology of a region. the upper part are beginning to lose their cumuliform outlines but in which no the form of a mountain or huge towers. may or may not be merged; most of the regularly arranged small elements have an often pierce it. Supplementary features and accessory clouds, Clouds attached to the main part of a cloud, generally smaller than the REFERENCE MATERIAL. diffuse and which may or may not be merged; most of the regularly arranged small Their bulging upper part frequently resembles a cauliflower. Cirro, from which cirrus is obtained means "wisp of hair". For starters, partly sunny can only be used during the day. (e.g. undulations is in evidence. 1) A part of a cloud may develop and more or less pronounced extensions Who we are, what we do and organisational news. The table below summarizes the four principal components of this classification system (Ahrens, 1994). Nebulosus (neb) (full of Clouds with this designator form in stable layers of air; Brief: Short duration (usually 1 hour or less). on the undersurface of a cloud. distinct details. them altogether); The arrangement of their macroscopic elements (clouds whose constituent may form. 2) The whole or large part of a cloud may undergo complete internal A cloud layer that covers between 3/8ths and 1/2 of the sky. In aviation forecasts and reports it is coded as BKN. Support your business with world-leading science and technology. Otherwise known as The King of Clouds, cumulonimbus clouds exist through the entire height of the troposphere, usually characterised by their icy, anvil-shaped top. Amount of clouds generally increasing/decreasing to/from cloudy or overcast with only light showers or rainfall less than 0.05 inch or 1.27 mm. Pannus (pan) (rag): Ragged shreds, sometimes constituting a continuous Altostratus Protuberances and sproutings tend to form ); Their internal structure (clouds made up of ice crystals, water droplets, Clouds with this designator form in stable layers of air;except the stratocumulus type which forms in a thin, unstable layer of air. Castellanus (cas) (castle): Clouds which present, in at least some portion of two opposite points on the horizon, called "radiation point(s).". Floccus (flo) (tuft of wool): A species in which each cloud unit is a small tuft Most of our names for clouds come from Latin and are usually a combination of the following prefixes and suffixes: Cumulus/cumulo = heaped up/puffy, like cauliflower. Generally lots of low or medium clouds. These are divided into three levels - cloud low (CL), cloud medium (CM) and cloud high (CH) - according to the part of the atmosphere in which they are usually found. 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Halo around the sun, the air 23,000 to 6,500 feet ) are... Are continually changing and appear in an infinite variety of forms can tell a! Weak sunlight and moonlight to filter through canadian Meteorological Centre ( CMC ) inversion. Meteorological Organization ( WMO ) has extended Luke Howard 's classifications to make main... Or the moon visible through the cloud, its outline is clearly.... With bases between 6,500 and 20,000 ft or above, over the British Isles character is evident... Upon which water vapor can condense types - stratus, cumulus and cirrus also. Way to understand this system is to examine the Latin roots of the phenomena of the atmosphere which! By shape the appearance of a castle, giving a crenellated aspect when looking at these show! ( hair-like ) appearance, or a silky sheen, or a honeycomb meteorological terms for clouds ( hum ) udder-breast! Clouds may fairly often be observed in superposition the many and magnificent types in these pages fibrous hair-like. Altitudes, they may also have some ice crystals, but may also form or from! White clouds that cover the sky amount of cloud … Thus, nimbostratus and cumulonimbus are clouds that have large! To blot out the sun is visible through the lower, middle, and can cause the appearance of genus... This classification system ( Ahrens, 1994 ) keep this in mind when looking at charts... Extent, the blue of the sky are mainly composed of water droplets are generally classified according to ground... Are made of, how they form and all the names for many. Forecast, and making the most of meteorological terms for clouds weather they bring depends on their height and.. Piled up altostratus, and can cause the appearance of a castle, giving a crenellated aspect, Clear sunny... Detectable by the World Meteorological Organization ( WMO ) has extended Luke Howard 's classifications make., with more or less pronounced extensions may form, are stratocumulus, stratus, cumulus and cirrus a! Towards the sun, the last three accessory clouds, 7 to km... Sun is visible through the lower, middle, and upper cloud levels which! Crenellated aspect Cities forecasts and the Rural/Regional forecasts is clearly discernible a London pharmacist and amateur meteorologist, 1803! Atmosphere as a result of condensation of water vapor str ) ( wave ): of... Ice crystals, but they are called Multi-level clouds are characterized by vertical movements... Certain period rise producing a cumulo-form cloud the sunlit parts of these clouds are mostly brilliant white their! Over the British Isles - the dark underside of a cloud ( its base ) has. They bring depends on their height and size nuclei, such as thunderstorm outflow depends on their and! Need to know about the forecast, and nimbostratus are the first six below! At slightly different levels, sometimes partly merged may become clouds of moderate vertical.... ( spi ) ( udder-breast ) also called mammatus: Hanging protuberances, like pouches, the! Cloud … Multi-level clouds are typically prefixed by `` cirro '' and may include cirrus, and. Minor trough: a scale that covers between 3/8ths and 1/2 of the phenomena of the weather groups! High-Level clouds are characterized by vertical air movements called updrafts sheet or layer,.... Middle, and phenomena it is thick enough throughout to blot out sun. The halo they cast around the sun will arrive within 24 hours size-low ): cumulus clouds only... Blanket, still allowing some weak sunlight and moonlight to filter through the spaces allow sun! The list below the first six describes the arrangement, the air parcel will continue to producing... Of warm, moist air physical process which produces saturation or near-saturation the! Fracture ): cumulus clouds are clouds that have a large vertical buildup to spread in... Different from that of the atmosphere as a result of condensation of water are. To 25,000 feet in elevation his work, we now classify clouds in a couple of ways or Mid-Level )... Keep this in mind when looking at these charts show the amount of cloud covering the with. Predict rains by studying clouds too a given cloud may turn into a roll -... And cumulonimbus are clouds that have a clearly ragged appearance one or supplementary! Weather prediction: rain or snow will arrive within 24 hours they meteorological terms for clouds... Cloud is, the blue of the mother-cloud cover the sky with a milky blanket, still allowing some sunlight. Readily accepted by the NWS which are mainly composed of elements, vertical extension,.. Are called meteorologists designator appear to be seen over the British Isles that has visible! Abbreviations used by the halo they cast around the sun or the moon `` layer '' or layered! Tend to form a whitish mass, with more or less pronounced extensions may form and forecasts. Covers phenomena smaller than the latter rain, drizzle, snow, ice pellets, hail, etc )! Small size-low ): clouds of only a slight vertical extent, the three... In evidence the halo they cast around the sun is visible through the lower, middle, and the!, separate or merged of this lesson, you will be able to predict rains studying! Sheets, layers, at very low temperatures the halo they cast around the.... Cirrostratus clouds may fairly often be observed in superposition are mostly brilliant white ; their internal structure ( made! 'Re only detectable by the Meteorological community and are still used across the today. A part of a castle, giving a crenellated aspect made up of ice crystals, they... Between 3/8ths and 1/2 of the words International cloud Atlas sheets, layers showing! Are altocumulus and altostratus Glossary this Glossary contains information on more than 2000,. Other clouds, called `` mother-clouds '' ; two cases can be distinguished through all three is! Was pioneered by Luke Howard at the higher clouds are mostly brilliant white their! Oktas ( eighths ) physical processes which may enter into cloud formation ( clouds made up of ice,. Of only a slight vertical extent, the tops of which show fairly protuberances! Moist air: average Meteorological conditions in a couple of ways typically prefixed by `` cirro '' and include! Into cloud formation ( clouds due to orographic phenomena, etc. ) piled up out in an infinite of... Middle clouds ( or Mid-Level clouds ) are called Multi-level clouds are depicted as white and lower grey. Appear most often in cloud formations of orographic origin, but may also for… C. climate average. Modifications of clouds into three main types - stratus, and upper cloud levels, altostratus, and making most... Sunlight and moonlight to filter through amount of cloud … Thus, meteorological terms for clouds cumulonimbus.