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63-580: The town is about 300 metres (330 yards) across a small river from the Nigerian village of Gamboru , where Fotokol residents often go for supplies. In 2014, the Gamboru Ngala massacre by jihadist group Boko Haram killed 300 people, endangering Fotokol residents as well. As of June 2014, " soldiers and paramilitary officers have been deployed in ... [Fotokol] to provide security for residents and allow children to safely attend school." In September 2014,

126-430: A characteristic other than altitude. Clouds that form in the low level of the troposphere are generally of larger structure than those that form in the middle and high levels, so they can usually be identified by their forms and genus types using satellite photography alone. These clouds have low- to mid-level bases that form anywhere from near the surface to about 2,400 m (8,000 ft) and tops that can extend into

189-590: A cloudlet of the species humilis that shows only slight vertical development. If the air becomes more unstable, the cloud tends to grow vertically into the species mediocris , then strongly convective congestus , the tallest cumulus species which is the same type that the International Civil Aviation Organization refers to as 'towering cumulus'. With highly unstable atmospheric conditions, large cumulus may continue to grow into even more strongly convective cumulonimbus calvus (essentially

252-549: A common stratiform base. Castellanus resembles the turrets of a castle when viewed from the side, and can be found with stratocumuliform genera at any tropospheric altitude level and with limited-convective patches of high-level cirrus. Tufted clouds of the more detached floccus species are subdivisions of genus-types which may be cirriform or stratocumuliform in overall structure. They are sometimes seen with cirrus, cirrocumulus, altocumulus, and stratocumulus. A newly recognized species of stratocumulus or altocumulus has been given

315-552: A counterattack , to a Chadian assault, on Fotokol, killing 81 civilians , 13 Chadian and 6 Cameroonian soldiers. Boko Haram launched a series of suicide attacks in the town , leading to the region's governor to place restrictions on Islamic veils . On 6 January 2020, a bombing in Gamboru on the bridge which connects it to Fotokol killed at least 30 people. 12°22′N 14°14′E  /  12.367°N 14.233°E  / 12.367; 14.233 This Cameroon location article

378-499: A direct effect on climate change on Earth. They may reflect incoming rays from the Sun which can contribute to a cooling effect where and when these clouds occur, or trap longer wave radiation that reflects back up from the Earth's surface which can cause a warming effect. The altitude, form, and thickness of the clouds are the main factors that affect the local heating or cooling of the Earth and

441-550: A narrower line of clouds, which are mostly stratocumuliform, cumuliform, or cumulonimbiform depending on the stability of the warm airmass just ahead of the front. A third source of lift is wind circulation forcing air over a physical barrier such as a mountain ( orographic lift ). If the air is generally stable, nothing more than lenticular cap clouds form. However, if the air becomes sufficiently moist and unstable, orographic showers or thunderstorms may appear. Clouds formed by any of these lifting agents are initially seen in

504-474: A parcel of air containing invisible water vapor to rise and cool to its dew point, the temperature at which the air becomes saturated. The main mechanism behind this process is adiabatic cooling. As the air is cooled to its dew point and becomes saturated, water vapor normally condenses to form cloud drops. This condensation normally occurs on cloud condensation nuclei such as salt or dust particles that are small enough to be held aloft by normal circulation of

567-410: A powerful "ripple" in the atmosphere, the cloud may be "surfed" in glider aircraft. More general airmass instability in the troposphere tends to produce clouds of the more freely convective cumulus genus type, whose species are mainly indicators of degrees of atmospheric instability and resultant vertical development of the clouds. A cumulus cloud initially forms in the low level of the troposphere as

630-404: 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 . Clouds are seen in the Earth's homosphere , which includes the troposphere , stratosphere , and mesosphere . Nephology is the science of clouds, which is undertaken in

693-525: A specific altitude level or form, and can therefore be common to more than one genus or species. All cloud varieties fall into one of two main groups. One group identifies the opacities of particular low and mid-level cloud structures and comprises the varieties translucidus (thin translucent), perlucidus (thick opaque with translucent or very small clear breaks), and opacus (thick opaque). These varieties are always identifiable for cloud genera and species with variable opacity. All three are associated with

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756-527: A surface-based observer (cloud fields usually being visible only from a significant altitude above the formations). These varieties are not always present with the genera and species with which they are otherwise associated, but only appear when atmospheric conditions favor their formation. Intortus and vertebratus varieties occur on occasion with cirrus fibratus. They are respectively filaments twisted into irregular shapes, and those that are arranged in fishbone patterns, usually by uneven wind currents that favor

819-403: A third" as a result. The Boko Haram attack on Gamboru on May 5–6, 2014 , and its twin town of Ngala killed at least 300 people. Some residents reported that they planned to move to Cameroon in the wake of the attacks, and a Nigerian Army source indicated that corruption was hampering efforts to defend local residents. On May 9, 2014, it was reported that the bridge linking Gamboru to

882-411: A very tall congestus cloud that produces thunder), then ultimately into the species capillatus when supercooled water droplets at the top of the cloud turn into ice crystals giving it a cirriform appearance. Genus and species types are further subdivided into varieties whose names can appear after the species name to provide a fuller description of a cloud. Some cloud varieties are not restricted to

945-603: Is a stub . You can help Misplaced Pages by expanding it . Gamboru Gamboru (or Gamburu ) is a market town in Borno State , northeast Nigeria , near the Cameroon border. It is the administrative centre of Ngala local government area . A 2013 IRIN report indicated that pharmacies in Gamboru Ngala were subject to attack by Islamist insurgents Boko Haram , and that the prices of medicines had "gone up by at least

1008-446: Is a stub . You can help Misplaced Pages by expanding it . Cloud This is an accepted version of this page In meteorology , a cloud is an aerosol consisting of a visible mass of miniature liquid droplets , frozen crystals , or other particles suspended in the atmosphere of a planetary body or similar space. Water or various other chemicals may compose the droplets and crystals. On Earth , clouds are formed as

1071-525: Is a feature seen with clouds producing precipitation that evaporates before reaching the ground, these being of the genera cirrocumulus, altocumulus, altostratus, nimbostratus, stratocumulus, cumulus, and cumulonimbus. When the precipitation reaches the ground without completely evaporating, it is designated as the feature praecipitatio . This normally occurs with altostratus opacus, which can produce widespread but usually light precipitation, and with thicker clouds that show significant vertical development. Of

1134-565: Is a species made of semi-merged filaments that are transitional to or from cirrus. Mid-level altostratus and multi-level nimbostratus always have a flat or diffuse appearance and are therefore not subdivided into species. Low stratus is of the species nebulosus except when broken up into ragged sheets of stratus fractus (see below). Cirriform clouds have three non-convective species that can form in stable airmass conditions. Cirrus fibratus comprise filaments that may be straight, wavy, or occasionally twisted by wind shear. The species uncinus

1197-399: Is caused by localized downdrafts that create circular holes in the form of a honeycomb or net. It is occasionally seen with cirrocumulus and altocumulus of the species stratiformis, castellanus, and floccus, and with stratocumulus of the species stratiformis and castellanus. It is possible for some species to show combined varieties at one time, especially if one variety is opacity-based and

1260-416: Is one that has spread out into a clear anvil shape as a result of rising air currents hitting the stability layer at the tropopause where the air no longer continues to get colder with increasing altitude. The mamma feature forms on the bases of clouds as downward-facing bubble-like protuberances caused by localized downdrafts within the cloud. It is also sometimes called mammatus , an earlier version of

1323-423: Is oppressively hot, windy, and generally cloudy , whereas the wet season is oppressively hot, oppressive, and partially cloudy. The average annual temperature ranges from 58 to 106 degrees Fahrenheit, and it rarely falls below or rises over 111 degrees. 12°22′14″N 14°13′02″E  /  12.3706°N 14.2172°E  / 12.3706; 14.2172 This Borno State , Nigeria location article

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1386-427: Is similar but has upturned hooks at the ends. Cirrus spissatus appear as opaque patches that can show light gray shading. Stratocumuliform genus-types (cirrocumulus, altocumulus, and stratocumulus) that appear in mostly stable air with limited convection have two species each. The stratiformis species normally occur in extensive sheets or in smaller patches where there is only minimal convective activity. Clouds of

1449-464: The Nigerian Army said it had recaptured Gamboru from Boko Haram, along with the nearby towns of Mafa , Mallam Fatori, Abadam , and Marte , following joint military operations by Nigerian and Cameroonian forces, civilian forces, and three days of Chadian airstrikes. On 6 January 2020, a bomb at the marketplace on the bridge to Fotokol killed at least 30 people. In Gamboru, the dry season

1512-575: The United Nations announced that it was making efforts to move 5,000 refugees staying in Fotokol to safer locations, to avoid cross-border incursions by Nigerian insurgents . Over 8,000 refugees had already been moved to the Minawo refugee camp . On 29 and 30 January 2015, fighting between Chadian soldiers and Boko Haram was reported in Fotokol and surrounding areas. On 4 February 2015, Boko Haram launched

1575-845: The cloud physics branch of meteorology . There are two methods of naming clouds in their respective layers of the homosphere, Latin and common name . Genus types in the troposphere, the atmospheric layer closest to Earth's surface, have Latin names because of the universal adoption of Luke Howard 's nomenclature that was formally proposed in 1802. It became the basis of a modern international system that divides clouds into five physical forms which can be further divided or classified into altitude levels to derive ten basic genera . The main representative cloud types for each of these forms are stratiform , cumuliform , stratocumuliform , cumulonimbiform , and cirriform . Low-level clouds do not have any altitude-related prefixes. However mid-level stratiform and stratocumuliform types are given

1638-405: The lenticularis species tend to have lens-like shapes tapered at the ends. They are most commonly seen as orographic mountain- wave clouds , but can occur anywhere in the troposphere where there is strong wind shear combined with sufficient airmass stability to maintain a generally flat cloud structure. These two species can be found in the high, middle, or low levels of the troposphere depending on

1701-753: The polar regions , 5,000 to 12,200 m (16,500 to 40,000 ft) in the temperate regions , and 6,100 to 18,300 m (20,000 to 60,000 ft) in the tropics . All cirriform clouds are classified as high, thus constitute a single genus cirrus (Ci). Stratocumuliform and stratiform clouds in the high altitude range carry the prefix cirro- , yielding the respective genus names cirrocumulus (Cc) and cirrostratus (Cs). If limited-resolution satellite images of high clouds are analyzed without supporting data from direct human observations, distinguishing between individual forms or genus types becomes impossible, and they are collectively identified as high-type (or informally as cirrus-type , though not all high clouds are of

1764-516: The Greek word meteoros , meaning 'high in the sky'. From that word came the modern term meteorology , the study of clouds and weather. Meteorologica was based on intuition and simple observation, but not on what is now considered the scientific method. Nevertheless, it was the first known work that attempted to treat a broad range of meteorological topics in a systematic way, especially the hydrological cycle . After centuries of speculative theories about

1827-445: The air to its dew point. Conductive, radiational, and evaporative cooling require no lifting mechanism and can cause condensation at surface level resulting in the formation of fog . Several main sources of water vapor can be added to the air as a way of achieving saturation without any cooling process: evaporation from surface water or moist ground, precipitation or virga , and transpiration from plants. Classification in

1890-450: The air. One agent is the convective upward motion of air caused by daytime solar heating at surface level. Low level airmass instability allows for the formation of cumuliform clouds in the troposphere that can produce showers if the air is sufficiently moist. On moderately rare occasions, convective lift can be powerful enough to penetrate the tropopause and push the cloud top into the stratosphere. Frontal and cyclonic lift occur in

1953-401: The altitude at which each initially forms, and are also more informally characterized as multi-level or vertical . Most of the ten genera derived by this method of classification can be subdivided into species and further subdivided into varieties . Very low stratiform clouds that extend down to the Earth's surface are given the common names fog and mist , but have no Latin names. In

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2016-471: The altitude levels. Ancient cloud studies were not made in isolation, but were observed in combination with other weather elements and even other natural sciences. Around 340 BC, 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 clouds from which precipitation fell were called meteors, which originate from

2079-479: The atmosphere. Clouds that form above the troposphere are too scarce and too thin to have any influence on climate change. Clouds are the main uncertainty in climate sensitivity . The origin of the term "cloud" can be found in the Old English words clud or clod , meaning a hill or a mass of stone. Around the beginning of the 13th century, the word came to be used as a metaphor for rain clouds, because of

2142-459: The cirrus form or genus). Nonvertical clouds in the middle level are prefixed by alto- , yielding the genus names altocumulus (Ac) for stratocumuliform types and altostratus (As) for stratiform types. These clouds can form as low as 2,000 m (6,500 ft) above surface at any latitude, but may be based as high as 4,000 m (13,000 ft) near the poles, 7,000 m (23,000 ft) at midlatitudes, and 7,600 m (25,000 ft) in

2205-549: The formation and behavior of clouds, the first truly scientific studies were undertaken by Luke Howard in England and Jean-Baptiste Lamarck in France. Howard was a methodical observer with a strong grounding in the Latin language, and used his background to formally classify the various tropospheric cloud types during 1802. He believed that scientific observations of the changing cloud forms in

2268-426: The formation of these varieties. The variety radiatus is associated with cloud rows of a particular type that appear to converge at the horizon. It is sometimes seen with the fibratus and uncinus species of cirrus, the stratiformis species of altocumulus and stratocumulus, the mediocris and sometimes humilis species of cumulus, and with the genus altostratus. Another variety, duplicatus (closely spaced layers of

2331-476: The homosphere, which includes the troposphere, stratosphere, and mesosphere. Within these layers of the atmosphere , air can become saturated as a result of being cooled to its dew point or by having moisture added from an adjacent source. In the latter case, saturation occurs when the dew point is raised to the ambient air temperature. Adiabatic cooling occurs when one or more of three possible lifting agents – convective, cyclonic/frontal, or orographic – cause

2394-442: The largest of all cloud genera, has the capacity to produce very heavy showers. Low stratus clouds usually produce only light precipitation, but this always occurs as the feature praecipitatio due to the fact this cloud genus lies too close to the ground to allow for the formation of virga. Incus is the most type-specific supplementary feature, seen only with cumulonimbus of the species capillatus. A cumulonimbus incus cloud top

2457-522: The latitudinal geographical zone . Each altitude level comprises two or three genus-types differentiated mainly by physical form. The standard levels and genus-types are summarised below in approximate descending order of the altitude at which each is normally based. Multi-level clouds with significant vertical extent are separately listed and summarized in approximate ascending order of instability or convective activity. High clouds form at altitudes of 3,000 to 7,600 m (10,000 to 25,000 ft) in

2520-439: The latter, upward-growing cumulus mediocris produces only isolated light showers, while downward growing nimbostratus is capable of heavier, more extensive precipitation. Towering vertical clouds have the greatest ability to produce intense precipitation events, but these tend to be localized unless organized along fast-moving cold fronts. Showers of moderate to heavy intensity can fall from cumulus congestus clouds. Cumulonimbus,

2583-657: The mid-altitude range and sometimes higher in the case of nimbostratus. These very large cumuliform and cumulonimbiform types have cloud bases in the same low- to mid-level range as the multi-level and moderate vertical types, but the tops nearly always extend into the high levels. Unlike less vertically developed clouds, they are required to be identified by their standard names or abbreviations in all aviation observations (METARS) and forecasts (TAFS) to warn pilots of possible severe weather and turbulence. Genus types are commonly divided into subtypes called species that indicate specific structural details which can vary according to

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2646-436: The name pannus (see section on supplementary features). These species are subdivisions of genus types that can occur in partly unstable air with limited convection . The species castellanus appears when a mostly stable stratocumuliform or cirriform layer becomes disturbed by localized areas of airmass instability, usually in the morning or afternoon. This results in the formation of embedded cumuliform buildups arising from

2709-602: The name volutus , a roll cloud that can occur ahead of a cumulonimbus formation. There are some volutus clouds that form as a consequence of interactions with specific geographical features rather than with a parent cloud. Perhaps the strangest geographically specific cloud of this type is the Morning Glory , a rolling cylindrical cloud that appears unpredictably over the Gulf of Carpentaria in Northern Australia . Associated with

2772-451: The other is pattern-based. An example of this would be a layer of altocumulus stratiformis arranged in seemingly converging rows separated by small breaks. The full technical name of a cloud in this configuration would be altocumulus stratiformis radiatus perlucidus , which would identify respectively its genus, species, and two combined varieties. Supplementary features and accessory clouds are not further subdivisions of cloud types below

2835-401: The physical forms and genera with which each is normally associated. The forms, genera, and species are listed from left to right in approximate ascending order of instability or convective activity. Of the non-convective stratiform group, high-level cirrostratus comprises two species. Cirrostratus nebulosus has a rather diffuse appearance lacking in structural detail. Cirrostratus fibratus

2898-482: The prefix alto- while high-level variants of these same two forms carry the prefix cirro- . In the case of stratocumuliform clouds, the prefix strato- is applied to the low-level genus type but is dropped from the mid- and high-level varients to avoid double-prefixing with alto- and cirro-. Genus types with sufficient vertical extent to occupy more than one level do not carry any altitude-related prefixes. They are classified formally as low- or mid-level depending on

2961-459: The purpose of satellite analysis. They are given below in approximate ascending order of instability or convective activity. 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 , and weather maps . The base-height range for each level varies depending on

3024-473: The rest of Nigeria, and also linking "the immigration checkpoints of both Cameroon and Nigeria," had been destroyed. On May 11 it was reported that Borno State Governor Kashim Shettima had visited the town to view the destruction and offer condolences, and "promised to rebuild the Gamboru Ngala central market." Local government chairman Bakura Mustapha indicated that over 200 vehicles, and "hundreds of shops and houses" had been burned. On 2 February 2015,

3087-417: The same type, one above the other), is sometimes found with cirrus of both the fibratus and uncinus species, and with altocumulus and stratocumulus of the species stratiformis and lenticularis. The variety undulatus (having a wavy undulating base) can occur with any clouds of the species stratiformis or lenticularis, and with altostratus. It is only rarely observed with stratus nebulosus. The variety lacunosus

3150-478: 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. The table that follows is very broad in scope like the cloud genera template upon which it is partly based. There are some variations in styles of nomenclature between the classification scheme used for

3213-579: The sky could unlock the key to weather forecasting. Lamarck had worked independently on cloud classification the same year and had come up with a different naming scheme that failed to make an impression even in his home country of France because it used unusually descriptive and informal French names and phrases for cloud types. His system of nomenclature included 12 categories of clouds, with such names as (translated from French) hazy clouds, dappled clouds, and broom-like clouds. By contrast, Howard used universally accepted Latin, which caught on quickly after it

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3276-601: The species and variety level. Rather, they are either hydrometeors or special cloud types with their own Latin names that form in association with certain cloud genera, species, and varieties. Supplementary features, whether in the form of clouds or precipitation, are directly attached to the main genus-cloud. Accessory clouds, by contrast, are generally detached from the main cloud. One group of supplementary features are not actual cloud formations, but precipitation that falls when water droplets or ice crystals that make up visible clouds have grown too heavy to remain aloft. Virga

3339-453: The stability and windshear characteristics of the atmosphere at any given time and location. Despite this hierarchy, a particular species may be a subtype of more than one genus, especially if the genera are of the same physical form and are differentiated from each other mainly by altitude or level. There are a few species, each of which can be associated with genera of more than one physical form. The species types are grouped below according to

3402-475: The stratiformis species of altocumulus and stratocumulus. However, only two varieties are seen with altostratus and stratus nebulosus whose uniform structures prevent the formation of a perlucidus variety. Opacity-based varieties are not applied to high clouds because they are always translucent, or in the case of cirrus spissatus, always opaque. A second group describes the occasional arrangements of cloud structures into particular patterns that are discernible by

3465-615: The stratocumuliform genus or genera present at any given time. The species fractus shows variable instability because it can be a subdivision of genus-types of different physical forms that have different stability characteristics. This subtype can be in the form of ragged but mostly stable stratiform sheets (stratus fractus) or small ragged cumuliform heaps with somewhat greater instability (cumulus fractus). When clouds of this species are associated with precipitating cloud systems of considerable vertical and sometimes horizontal extent, they are also classified as accessory clouds under

3528-629: The stratosphere and mesosphere, clouds have common names for their main types. They may have the appearance of stratiform veils or sheets, cirriform wisps, or stratocumuliform bands or ripples. They are seen infrequently, mostly in the polar regions of Earth. Clouds have been observed in the atmospheres of other planets and moons in the Solar System and beyond. However, due to their different temperature characteristics, they are often composed of other substances such as methane , ammonia , and sulfuric acid , as well as water. Tropospheric clouds can have

3591-490: The tropics. As with high clouds, the main genus types are easily identified by the human eye, but distinguishing between them using satellite photography alone is not possible. When the supporting data of human observations are not available, these clouds are usually collectively identified as middle-type on satellite images. Low clouds are found from near the surface up to 2,000 m (6,500 ft). Genus types in this level either have no prefix or carry one that refers to

3654-487: The troposphere (strict Latin except for surface-based aerosols) and the higher levels of the homosphere (common terms, some informally derived from Latin). However, the schemes presented here share a cross-classification of physical forms and altitude levels to derive the 10 tropospheric genera, the fog and mist that forms at surface level, and several additional major types above the troposphere. The cumulus genus includes four species that indicate vertical size which can affect

3717-463: The troposphere during the late 19th century eventually led to the creation of separate classification schemes that reverted to the use of descriptive common names and phrases that somewhat recalled Lamarck's methods of classification. These very high clouds, although classified by these different methods, are nevertheless broadly similar to some cloud forms identified in the troposphere with Latin names. Terrestrial clouds can be found throughout most of

3780-424: The troposphere is based on a hierarchy of categories with physical forms and altitude levels at the top. These are cross-classified into a total of ten genus types, most of which can be divided into species and further subdivided into varieties which are at the bottom of the hierarchy. Clouds in the troposphere assume five physical forms based on structure and process of formation. These forms are commonly used for

3843-486: The troposphere when stable air is forced aloft at weather fronts and around centers of low pressure by a process called convergence . Warm fronts associated with extratropical cyclones tend to generate mostly cirriform and stratiform clouds over a wide area unless the approaching warm airmass is unstable, in which case cumulus congestus or cumulonimbus clouds are usually embedded in the main precipitating cloud layer. Cold fronts are usually faster moving and generate

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3906-403: The troposphere where these agents are most active. However, water vapor that has been lifted to the top of troposphere can be carried even higher by gravity waves where further condensation can result in the formation of clouds in the stratosphere and mesosphere. Along with adiabatic cooling that requires a lifting agent, three major nonadiabatic mechanisms exist for lowering the temperature of

3969-491: Was published in 1803. As a sign of the popularity of the naming scheme, German dramatist and poet Johann Wolfgang von Goethe composed four poems about clouds, dedicating them to Howard. An elaboration of Howard's system was eventually formally adopted by the International Meteorological Conference in 1891. This system covered only the tropospheric cloud types. However, the discovery of clouds above

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