Editing Altostratus cloud

{{good article}}
{{Short description|Type of middle-altitude cloud}}
[[File:2020-12-31 16 06 58 Altostratus with a wavy undulating base above the Dulles section of Sterling, Loudoun County, Virginia.jpg|upright=1.6|thumb|right|alt=An altostratus radiatus cloud showing the characteristic parallel lines of cloud.|''Altostratus radiatus'' cloud showing distinctive parallel bands]]
'''Altostratus''' is a middle-altitude [[cloud]] genus made up of water droplets, [[ice crystal]]s, or a mixture of the two. Altostratus clouds are formed when large masses of warm, moist air rise, causing water vapor to condense. Altostratus clouds are usually gray or blueish featureless sheets, although some variants have wavy or banded bases. The sun can be seen through thinner altostratus clouds, but thicker layers can be quite [[Opacity (optics)|opaque]].

Altostratus clouds usually predict the arrival of [[warm front]]s. Once altostratus clouds associated with a warm front arrive, continuous rain or snow will usually follow in the next 12 to 24 hours. Although altostratus clouds predict the arrival of warmer, wetter weather, they themselves do not produce significant precipitation. Thunderstorms can be embedded in altostratus clouds, however, bringing showers.

Because altostratus clouds can contain ice crystals, they can produce some optical phenomena like [[iridescence]] and [[Corona (optical phenomenon)|coronas]].

== Description ==
[[File:2017-06-22_16_57_51_Sun_shining_dimly_through_an_altostratus_cloud_layer_over_Ladybank_Lane_in_the_Chantilly_Highlands_section_of_Oak_Hill,_Fairfax_County,_Virginia.jpg|upright=1.3|thumb|right|alt=The sun shines diumly through a largely-featureless gray altostratus cloud.|Sun shines dimly though the ''translucidus'' variant of altostratus clouds]]
Altostratus clouds are generally gray or blue-tinged with a largely-uniform blanket-like appearance. They do not have distinct features, and usually do not produce [[precipitation]]. The name "altostratus" comes from the conjugation of the [[Latin]] words "altum", meaning "high", and "stratus", meaning "flat" or "spread out".<ref name="ICA-AS">{{harvnb|Cohn|Bruhn|Anderson|Atkinson|2017|loc=Section 2.3.5.1}}</ref><ref name="MetOffice">{{cite web|url=https://www.metoffice.gov.uk/weather/learn-about/weather/types-of-weather/clouds/mid-level-clouds/altostratus|title=Altostratus clouds|publisher=Meteorological Office of the UK|access-date=25 March 2022}}</ref> Altostratus clouds can produce [[virga]], causing the cloud base to appear hazy.<ref name="WMO-Desc" /> While they do not produce significant precipitation, altostratus clouds can cause light sprinkles or even small rain showers.<ref name="Cloud-Classification">{{cite web |last=Funk |first=Ted |title=Cloud Classifications and Characteristics |url=https://www.weather.gov/media/lmk/soo/cloudchart.pdf|access-date=25 March 2022 |work=The Science Corner |publisher=[[National Oceanic and Atmospheric Administration|NOAA]] |page=1}}</ref> Consistent rainfall and lowering of the cloud base causes altostratus to become [[nimbostratus]].<ref name="Ahrens-144">{{harvnb|Ahrens|2006|p=194}}</ref>

Unlike most other types of clouds, altostratus clouds are not subdivided into [[cloud species]] due to their largely-featureless appearance.<ref name="ICA-Species">{{harvnb|Cohn|Bruhn|Anderson|Atkinson|2017|loc=Section 2.3.5.2}}</ref> However, they still appear in five varieties: ''Altostratus duplicatus'', ''opacus'', ''radiatus'', ''translucidus'', and ''undulatus''.<ref name="ICA-Varieties">{{harvnb|Cohn|Bruhn|Anderson|Atkinson|2017|loc=Section 2.3.5.3}}</ref> ''Altostratus duplicatus'' is a rare form of altostratus clouds composed of two or more layers of cloud.<ref>{{harvnb|Cohn|Bruhn|Anderson|Atkinson|2017|loc=Section 2.3.5.3.3}}</ref> ''Translucidus'' is a [[translucent]] form of altostratus clouds, meaning that the sun or moon can be seen through the cloud,<ref>{{harvnb|Cohn|Bruhn|Anderson|Atkinson|2017|loc=Section 2.3.5.3.1}}</ref> whereas the ''opacus'' variety is opaque.<ref>{{harvnb|Cohn|Bruhn|Anderson|Atkinson|2017|loc=Section 2.3.5.3.2}}</ref> ''Radiatus'' is another rare variety. It has parallel bands of cloud that stretch toward the horizon.<ref>{{harvnb|Cohn|Bruhn|Anderson|Atkinson|2017|loc=Section 2.3.5.3.5}}</ref> The ''undulatus'' variety has an wavy appearance&mdash;the underside of the cloud appears to rise and fall.<ref>{{harvnb|Cohn|Bruhn|Anderson|Atkinson|2017|loc=Section 2.3.5.3.4}}</ref>

Altostratus and [[altocumulus cloud]]s, both of which are mid-level clouds,<ref name="Cloud-Classification" /> are commonly measured together in cloud cover studies. Together, they cover around 25% of the Earth's surface on average<ref name="Sassen-688" /> based on [[CALIPSO]] satellite data.<ref name="Sassen-679">{{harvnb|Sassen|Wang|2012|p=679}}</ref> This constitutes roughly one third of the Earth's total cloud cover.<ref name="Sassen-688" /> By itself, separated from altocumulus, altostratus covers ~16% of the Earth's surface.<ref name="Sassen-688">{{harvnb|Sassen|Wang|2012|p=688}}</ref> Altostratus cloud cover varies seasonally in temperate regions, with significantly less coverage in the summer months as compared to the other seasons. Additionally, altostratus cloud cover varies by [[latitude]], with tropical regions having vastly fewer altostratus clouds when compared to temperate or polar regions.<ref name="Sassen-686">{{harvnb|Sassen|Wang|2012|p=686}}</ref> Altostratus and altocumulus cover roughly 22% of the ocean's surface based on surface measurements, with minimal variation based on season.<ref>{{harvnb|Warren|Hahn|London|Chervin|Jenne|1988|loc=Table 9b}}</ref>

Altostratus clouds are warmest at the bottom and coldest at the top,<ref name="Yang-6010">{{harvnb|Yang|Zou|2013|p=6010}}</ref> with a fairly consistent<ref name="Yang-6013" /> [[lapse rate]] of 5 to 7&nbsp;°C per kilometer (14 to 20&nbsp;°F per mile) inside the cloud. The lapse rate is the rate at which the temperature decreases with altitude.<ref name="Yang-6011">{{harvnb|Yang|Zou|2013|p=6011}}</ref> Higher lapse rates (i.e. the faster temperature drops with increasing altitude) were associated with colder clouds.<ref name="Yang-6013">{{harvnb|Yang|Zou|2013|p=6013}}</ref> The average temperature of altostratus clouds, based on data collected from roughly 45° to 80° latitude, varied from around {{convert|-16|to|-45|C|F|sigfig=2}}. Warmer temperatures occurred during summer and colder temperatures during winter.<ref name="Yang-6010" />

Inside altostratus clouds, the [[relative humidity]] is generally greatest towards the top of the cloud decreasing slowly and roughly linearly towards the bottom. The lowest part of the cloud has the lowest relative humidity.<ref name="Yang-6010" /> Below the bottom of the cloud, the relative humidity drops rapidly.<ref name="Danne-181">{{harvnb|Danne|Quante|Milferstädt|Lemke|1999|p=181}}</ref>

=== Microphysical properties ===
Altostratus can be composed of water droplets, [[supercooled]] water droplets, and ice crystals,<ref name="Cloud-Classification" /> but ice crystals make up the vast majority.<ref>{{harvnb|Sassen|Wang|2012|pp=679–680}}</ref> In some altostratus clouds made of ice crystals, very thin horizontal sheets of water droplets can appear seemingly at random, but they quickly disappear.<ref name="platt-344">{{harvnb|Platt|1977|p=344}}</ref> The sizes of the ice crystals in the cloud tended to increase as altitude decreased. However, close to the bottom of the cloud, the particles decreased in size again. During the sampling of one cloud, the scientists noted a [[Halo (optical phenomenon)|halo]] while flying near the top of the cloud, which indicated that the ice crystals were hexagonal near the top. However, farther down, the ice crystals became more conglomerated.<ref name="field-1929">{{harvnb|Field|1999|p=1929}}</ref><ref name="field-1933">{{harvnb|Field|1999|p=1933}}</ref> Mixed-phase (containing both ice and water) altostratus clouds contain a "melt layer", below which the ice crystals tend to melt into water droplets. These water droplets are spheres and thus fall much faster than ice crystals, collecting at the bottom of the cloud.<ref name="Danne-182">{{harvnb|Danne|Quante|Milferstädt|Lemke|1999|p=182}}</ref>

== Formation ==
[[File:Warm front.svg|thumb|right|upright=2.2|alt=A labeled diagram showing a warm front and the order in which clouds arrive.|Diagram of a warm front]]
Altostratus clouds form when a large [[Air mass|mass of warm air]] rises, causing water vapor in the atmosphere to condense onto nuclei (small dust particles), forming water droplets and ice crystals.<ref name="ucar">{{cite web|url=https://scied.ucar.edu/learning-zone/clouds/how-clouds-form|title=Clouds and How They Form|publisher=University Corporation for Atmospheric Research|access-date=28 March 2022|website=Center for Science Education}}</ref> These conditions usually happen at the leading edge of a warm front, where [[cirrostratus cloud]]s thicken and lower until they transition into altostratus clouds.<ref name="MetOffice" /> Alternatively, nimbostratus clouds can thin into altostratus.<ref name="Cohn-s2355" /> Altostratus can even form from the spreading of the upper [[anvil cloud]] or the middle column of a thunderstorm.<ref name="Cohn-s2355">{{harvnb|Cohn|Bruhn|Anderson|Atkinson|2017|loc=Section 2.3.5.5}}</ref>

Altostratus clouds are mid-level clouds<ref name="Cloud-Classification" /> that form from {{convert|2000|to|4000|m|ft|sigfig=2}} above sea level in [[Polar regions of Earth|polar regions]]. In [[Temperate climate|temperate regions]], the ceiling increases drastically, allowing altostratus clouds to form between {{convert|2000|to|7000|m|ft|sigfig=2}}. In [[Tropical climate|tropical regions]], altostratus can reach even higher, forming from {{convert|2000|to|8000|m|ft|sigfig=2}}.<ref name="WMO-Desc" /> They can range from {{convert|1000|to|5000|m|ft|sigfig=2}} in thickness<ref name="WMO-Desc" /> and can cover hundreds of kilometers of the Earth's surface.<ref>{{harvnb|Cohn|Bruhn|Anderson|Atkinson|2017|loc=Section 2.3.5.7}}</ref>

== Use in forecasting ==
{{see also|Weather forecasting}}
Altostratus clouds tend to form ahead of [[warm front]]s or [[occluded front]]s and herald their arrival.<ref name="MetOffice" /> These warm fronts bring warmer air into the region. Occluded fronts form when a faster-moving cold front catches up to a warm front, and the temperature after the frontal system passes may rise or fall.<ref name="frontal-systems">{{cite web|url=https://scied.ucar.edu/learning-zone/how-weather-works/weather-fronts|title=Weather Fronts|publisher=University Corporation for Atmospheric Research|access-date=28 March 2022|website=Center for Science Education}}</ref> As the frontal system approaches, cirrostratus clouds will thicken into altostratus clouds, which then gradually thicken further into nimbostratus clouds.<ref name="MetOffice" /><ref name="ahrens-120"/> If the frontal system is occluded, [[cumulonimbus cloud]]s may also be present.<ref name="frontal-systems" /> Once the altostratus clouds have arrived, rain or snow will usually follow in the next 12 to 24 hours.<ref name="ahrens-120"/>

Instability in the atmosphere can embed [[Cumulonimbus cloud|thunderstorms]] in an altostratus cloud,<ref name="WMO-Desc" /> although altostratus clouds themselves do not produce storms.<ref name="Cloud-Classification" />

== Effects on climate ==
Globally, clouds reflect around 50 [[watt]]s per square meter{{efn|To break this number, <math>50 \frac{W}{m^2}</math> down into practical terms, 50 watts is enough energy to raise the temperature of 1 liter (1 kilogram) of water by .012&nbsp;°C every second or around 43&nbsp;°C every hour. This amount of energy is being reflected by the averaged global cloud cover every single square meter. <math>Q = m \cdot c \cdot \Delta T \rightarrow \Delta T = \frac{Q}{m \cdot c} = \frac{50 J}{1 kg \cdot 4186 \frac{J}{kg \cdot ^{\circ} C}} = .012 ^{\circ} C</math>}} of short-wave solar radiation back into space, cooling the Earth by around {{convert|12|C-change|abbr=on}}, an effect largely caused by [[stratocumulus cloud]]s. However, at the same time, they reflect around 30 watts per square meter of long-wave (infrared) [[black body radiation]] emitted by the Earth back to Earth's surface, heating the Earth by around {{convert|7|C-change|abbr=on}}&mdash;a process called the [[greenhouse effect]]. [[Cirrus cloud|Cirrus]] and altostratus clouds are the top two sources of this heating effect. This combination of heating and cooling sums out to a net loss of 20 watts per square meter globally, cooling the Earth by roughly {{convert|5|C-change|abbr=on}}.<ref name="cloud-heating">{{cite web |url=http://isccp.giss.nasa.gov/role.html|title=Cloud Climatology|work=International Satellite Cloud Climatology Program|publisher=National Aeronautics and Space Administration|access-date=12 July 2011}}</ref><ref name="CRE">{{cite web|url=https://www.gfdl.noaa.gov/cloud-radiative-effect/|title=Cloud Radiative Effect|publisher=National Oceanic and Atmospheric Administration|website=Geophysical Fluid Dynamics Laboratory|access-date=29 March 2022}}</ref><ref name="Lecuyer-6213">{{harvnb|L'Ecuyer|Hang|Matus|Wang|2019|p=6213}}</ref><ref name="earthobs-global-warming">{{cite web|url=http://earthobservatory.nasa.gov/Features/GlobalWarming/|publisher=National Aeronautics and Space Administration|title=Global Warming: Feature Articles|access-date=29 March 2022|work=Earth Observatory|date=3 June 2010|last=Riebeek|first=Holli}}</ref>

Altostratus clouds are the only cloud genus besides cirrus clouds to exhibit a net global heating effect on Earth and its atmosphere; however, cirrus have a heating effect that is four times as potent as altostratus (2&nbsp;watts per square meter versus only 0.5&nbsp;watts per square meter).<ref>{{harvnb|L'Ecuyer|Hang|Matus|Wang|2019|p=6205}}</ref>

== Optical phenomena ==
Altostratus clouds can produce bright [[Halo (optical phenomenon)|halos]] when viewed from the air,<ref name="WMO-Desc">{{cite web|url=https://cloudatlas.wmo.int/en/observation-of-clouds-from-aircraft-descriptions-altostratus.html|title=Altostratus|access-date=25 March 2022|publisher=World Meteorological Organization|website=International Cloud Atlas}}</ref> but not when viewed from the ground.<ref>{{harvnb|Cohn|Bruhn|Anderson|Atkinson|2017|loc=Section 2.3.5.6.2}}</ref> Halos can take the appearance of rings, arcs, or spots of white or multicolored light and are formed by the [[Reflection (optics)|reflection]] and [[refraction]] of sunlight or moonlight shining through ice crystals in the cloud.<ref>{{harvnb|Cohn|Bruhn|Anderson|Atkinson|2017|loc=Section 3.2.3.1}}</ref> Light diffraction through altostratus clouds can also produce [[Corona (optical phenomenon)|coronas]], which are small, concentric pastel-colored rings of light around the sun or moon. They can also be [[Iridescence|iridescent]], with often-parallel bands of bright color projected on a cloud. Unlike the halos, the coronas and iridescence can be seen from Earth's surface.<ref name="MetOffice" /><ref>{{harvnb|Cohn|Bruhn|Anderson|Atkinson|2017|loc=Section 3.2.3.2 &ndash; 3.2.3.3}}</ref>

== Relation to other clouds ==
{{See also|List of cloud types}}
[[File:Cloud types en.svg|thumb|left|upright=1.6|alt=A diagram showing clouds at various heights|Heights of various cloud genera including high-, mid-, and low-level clouds]]
Altostratus and [[altocumulus cloud]]s are the two genera of mid-level clouds that usually form between {{convert|6500|and|20000|ft|m|order=flip|abbr=on}}.<ref name="Cloud-Classification" /><ref name="wmo-cloud-classification" /> These are given the prefix "alto-". These clouds are formed from ice crystals, supercooled water droplets, or liquid water droplets.<ref name="Cloud-Classification" />

Above the mid-level clouds are three different genera of high-level clouds, [[Cirrus cloud|cirrus]], [[cirrocumulus]], and cirrostratus, all of which are given the prefix "cirro-". High-level clouds usually form above {{convert|20000|ft|m|order=flip|abbr=on}}.<ref name="Cloud-Classification" /><ref name="wmo-cloud-classification">{{cite web|url=https://public-old.wmo.int/en/WorldMetDay2017/classifying-clouds|archive-url=https://web.archive.org/web/20231218182558/https://public-old.wmo.int/en/WorldMetDay2017/classifying-clouds|url-status=dead|archive-date=December 18, 2023|accessdate=14 March 2022|title=Classifying clouds| date=18 January 2017 |publisher=[[World Meteorological Organization]]}}</ref><ref name="H&H-340">{{harvnb|Hubbard|2000|p=340}}</ref> Cirrocumulus and cirrostratus are sometimes informally referred to as ''cirriform clouds'' because of their frequent association with cirrus.<ref>{{cite web|url=https://glossary.ametsoc.org/wiki/Cirriform|title=Cirriform – Glossary of Meteorology|access-date=23 February 2022|publisher=American Meteorological Society}}</ref>

Below the mid-level clouds are the low-level clouds, which usually form below {{convert|6500|ft|m|order=flip|abbr=on}} and do not have a prefix.<ref name="Cloud-Classification" /><ref name="wmo-cloud-classification" /> The two genera that are strictly low-level are [[stratus cloud|stratus]], and [[stratocumulus cloud|stratocumulus]]. These clouds are composed of water droplets, except during winter when they are formed of [[supercooled water]] droplets or ice crystals if the temperature at cloud level is below freezing. Three additional genera usually form in the low altitude range, but may be based at higher levels under conditions of very low humidity. They are the genera [[cumulus cloud|cumulus]], and [[cumulonimbus cloud|cumulonimbus]], and [[Nimbostratus cloud|nimbostratus]]. These are sometimes classified separately as clouds of vertical development, especially when their tops are high enough to be composed of supercooled water droplets or ice crystals.<ref name="Plymouth State Meteorology">{{cite web | url=http://vortex.plymouth.edu/clouds.html/ | title=Plymouth State Meteorology Program Cloud Boutique | author=Koermer, Jim | year=2011 | access-date=2 April 2012 | publisher=[[Plymouth State University]] | archive-date=10 May 2009 | archive-url=https://web.archive.org/web/20090510231716/http://vortex.plymouth.edu/clouds.html/ | url-status=dead }}</ref><ref name="Cloud-Classification" />

=== Cirrostratus ===
{{Main|Cirrostratus cloud}}
[[File:Close Cirrostratus.jpg|thumb|alt=Milky-white cirrostratus clouds cause the sky to appear lighter and have a milky tint.|Cirrostratus cloud]]

Cirrostratus clouds can appear as a smooth veil in the sky<ref>{{harvnb|Cohn|Bruhn|Anderson|Atkinson|2017|loc=Section 2.3.3.1}}</ref> or as a striated sheet.<ref name="H&H-340"/> They are sometimes similar to altostratus and are distinguishable from the latter because the sun or moon is always clearly visible through transparent cirrostratus, in contrast to altostratus which tends to be opaque or translucent.<ref name="Day-56">{{harvnb|Day|2005|p=56}}</ref> Cirrostratus come in two species, ''fibratus'' and ''nebulosus''.<ref>{{harvnb|Cohn|Bruhn|Anderson|Atkinson|2017|loc=Section 2.3.3.2}}</ref> The ice crystals in these clouds vary depending upon the height in the cloud. Towards the bottom, at temperatures of around {{convert|-35|to|-45|C|F}}, the crystals tend to be long, solid, hexagonal columns. Towards the top of the cloud, at temperatures of around {{convert|-47|to|-52|C|F}}, the predominant crystal types are thick, hexagonal plates and short, solid, hexagonal columns.<ref name="parungo-254">{{harvnb|Parungo|1995|p=254}}</ref><ref name="parungo-256">{{harvnb|Parungo|1995|p=256}}</ref> These clouds commonly produce halos, and sometimes the halo is the only indication that such clouds are present.<ref name="ahrens-120">{{harvnb|Ahrens|2006|p=120}}</ref> They are formed by warm, moist air being lifted slowly to a very high altitude.<ref>{{harvnb|Hamilton|2007|p=24}}</ref> When a warm front approaches, cirrostratus clouds become thicker and descend forming altostratus clouds,<ref name="Cloud-Classification"/> and rain usually begins 12 to 24 hours later.<ref name="ahrens-120"/>

=== Altocumulus ===
{{Main|Altocumulus cloud}}
[[File:Altocumulus cloud.jpg|thumb|alt=Small shreds of white altocumulus clouds against a blue sky.|Altocumulus clouds]]
Altocumulus clouds are small patches or heaps of white or light gray cloud.<ref>{{harvnb|Cohn|Bruhn|Anderson|Atkinson|2017|loc=Section 2.3.4.1}}</ref><ref name="Cloud-Classification" /> Like altostratus, altocumulus are composed of a mixture of water droplets, supercooled water droplets, and ice crystals. Although altocumulus clouds are mid-level clouds that form at roughly the same altitude as altostratus clouds, their formation methods are completely different. Altocumulus forms from [[convection|convective]] (rising) processes,<ref name="Cloud-Classification" /> whereas altostratus is usually formed by descending and thickening cirrostratus.<ref name="MetOffice" />

=== Stratus ===
{{Main|Stratus cloud}}
[[File:2020-05-18 09 13 58 Stratus clouds with bases that are about 700 feet above ground level over the KLWX WSR-88D NEXRAD in the Dulles section of Sterling, Loudoun County, Virginia.jpg|thumb|alt=A featureless gray stratus cloud.|Stratus cloud]]
Stratus are low-level clouds that are usually visually similar to altostratus.<ref name="Cloud-Classification" /> Stratus comes in two species: ''nebulosus'', a largely-featureless flat gray cloud sheet, and ''fractus'', shattered fragments of cloud<ref>{{harvnb|Cohn|Bruhn|Anderson|Atkinson|2017|loc=Section 2.3.8.2}}</ref> often called "scud".<ref name="Cloud-Classification" /> Opaque varieties of altostratus and ''stratus nebulosus'' clouds can be virtually indistinguishable from each other to the naked eye, to the point that the [[World Meteorological Organization]] suggests that one of the few ways to distinguish between these clouds is to check what types of clouds came before them.<ref name="Cohn-s23566">{{harvnb|Cohn|Bruhn|Anderson|Atkinson|2017|loc=Section 2.3.5.6.6}}</ref> Altostratus clouds, because they tend to form from warm fronts,<ref name="MetOffice" /> are usually preceded by high-level cirriform clouds.<ref name="Cohn-s23566" /> Stratus clouds tend to form by cooling air masses, often at night,<ref>{{harvnb|Cohn|Bruhn|Anderson|Atkinson|2017|loc=Section 2.3.8.8}}</ref> and thus are not usually preceded by other types of clouds.<ref name="Cohn-s23566" />

=== Nimbostratus ===
{{Main|Nimbostratus cloud}}
Nimbostratus are low-level (sometimes classified as vertical) rain-bearing stratus clouds. Unlike the sprinkles or light drizzles that altostratus or stratus can produce, nimbostratus produces heavy, continuous rain or snow. These clouds are thick and dark enough to entirely blot out the sun.<ref name="Cloud-Classification" /><ref>{{harvnb|Cohn|Bruhn|Anderson|Atkinson|2017|loc=Section 2.3.6.1}}</ref> Nimbostratus has no species<ref>{{harvnb|Cohn|Bruhn|Anderson|Atkinson|2017|loc=Section 2.3.6.2}}</ref> or varieties.<ref>{{harvnb|Cohn|Bruhn|Anderson|Atkinson|2017|loc=Section 2.3.6.3}}</ref> Like altostratus, nimbostratus clouds can be made of ice crystals, supercooled water droplets, or water droplets.<ref>{{harvnb|Cohn|Bruhn|Anderson|Atkinson|2017|loc=Section 2.3.6.7}}</ref>
{{clear}}

==See also==
{{commons category|Altostratus clouds}}
*[[List of cloud types]]

== Notes ==
{{notelist}}

== Sources ==
; Footnotes
{{Reflist}}

; Bibliography
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*{{cite book|last1=Hubbard|first1=Richard Keith|title=Boater's Bowditch: The Small Craft American Practical Navigator|chapter-url=https://books.google.com/books?id=nfWSxRr8VP4C&pg=PA340|edition=2nd|date=5 May 2000 |publisher=International Marine/Ragged Mountain Press|isbn=978-0-07-136136-1|chapter=Glossary}} <!-- Hubbard -->
*{{cite book|chapter-url=http://old.iupac.org/goldbook/A00257.pdf|publisher=[[International Union of Pure and Applied Chemistry]] (IUPAC)|title=IUPAC Compendium of Chemical Terminology|chapter=Altostratus Cloud (in Atmospheric Chemistry)|edition=2|year=1997|access-date=20 April 2011|archive-date=4 March 2016|archive-url=https://web.archive.org/web/20160304045646/http://old.iupac.org/goldbook/A00257.pdf|url-status=dead}} <!-- IUPAC -->
*{{cite journal|title=Reassessing the Effect of Cloud Type on Earth's Energy Balance in the Age of Active Spaceborne Observations. Part I: Top of Atmosphere and Surface|last1=L'Ecuyer|first1=Tristan|last2=Hang|first2=Yun|last3=Matus|first3=Alexander|last4=Wang|first4=Zhien|date=1 October 2019|volume=32|issue=19|publisher=American Meteorological Society|journal=Journal of Climate|pages=6197–6217|doi=10.1175/JCLI-D-18-0753.1|bibcode=2019JCli...32.6197L|doi-access=}} <!-- L'Ecuyer -->
*{{cite journal|title=Ice Crystals in High Clouds and Contrails|journal=Atmospheric Research|volume=38 |issue=1–4|first=F.|last=Parungo|oclc=90987092|doi=10.1016/0169-8095(94)00096-V|date=May 1995|pages=249–262 |bibcode=1995AtmRe..38..249P }} <!-- Parungo -->
*{{Cite journal|title=Lidar Observation of a Mixed-Phase Altostratus Cloud|first=C. M. R.|last=Platt|date=April 1977|journal=Journal of Applied Meteorology|volume=16|pages=339–345|issue=4|issn=0021-8952|doi=10.1175/1520-0450(1977)016<0339:LOOAMP>2.0.CO;2|bibcode = 1977JApMe..16..339P |doi-access=free}} <!-- Platt -->
*{{Cite journal|title=The Clouds of the Middle Troposphere: Composition, Radiative Impact, and Global Distribution|last1=Sassen|first1=Kenneth|last2=Wang|first2=Zhien|doi=10.1007/s10712-011-9163-x|date=2012|journal=Surveys in Geophysics|volume=33|issue=3–4|pages=677–691|bibcode=2012SGeo...33..677S|s2cid=129776090}} <!-- Sassen -->
*{{cite journal|title=Global Distribution of Total Cloud Cover and Cloud Type Amounts over the Ocean|last1=Warren|first1=Stephen G.|last2=Hahn|first2=Carol J.|last3=London|first3=Julius|last4=Chervin|first4=Robert M.|last5=Jenne|first5=Roy L.|date=December 1988|publisher=[[United States Department of Energy]]|journal=Office of Energy Research|doi=10.2172/5415329|url=https://www.osti.gov/servlets/purl/5415329|access-date=26 March 2022|doi-access=free}} <!-- Warren -->
*{{cite journal|title=Temperature Profiles and Lapse Rate Climatology in Altostratus and Nimbostratus Clouds Derived from GPS RO Data|last1=Yang|first1=S.|last2=Zou|first2=X.|date=15 August 2013|journal=Journal of Climate|publisher=American Meteorological Society|doi=10.1175/JCLI-D-12-00646.1|doi-access=free|volume=26|issue=16|pages=6000–6014|bibcode=2013JCli...26.6000Y}} <!-- Yang -->

{{Cloud types}}

{{DEFAULTSORT:Altostratus Cloud}}
[[Category:Stratus]]
[[Category:Cloud types]]