![Mammatus clouds in the Nepal Himalayas](https://upload.wikimedia.org/wikipedia/commons/4/42/Mammatus_clouds_in_the_Nepal_Himalayas.jpg)
Mammatus (also called mamma
or mammatocumulus, meaning "mammary cloud") is a cellular pattern of pouches hanging underneath the
base of a
cloud
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 ...
, typically a
cumulonimbus
Cumulonimbus (from Latin ''cumulus'', "heaped" and ''nimbus'', "rainstorm") is a dense, towering vertical cloud, typically forming from water vapor condensing in the lower troposphere that builds upward carried by powerful buoyant air currents. ...
raincloud, although they may be attached to other classes of parent clouds. The name ''mammatus'' is derived from the Latin ''
mamma'' (meaning "
udder
An udder is an organ formed of two or four mammary glands on the females of dairy animals and ruminants such as cattle, goats, and sheep. An udder is equivalent to the breast in primates and elephantine pachyderms. The udder is a single mass han ...
" or "
breast
The breast is one of two prominences located on the upper ventral region of a primate's torso. Both females and males develop breasts from the same embryological tissues.
In females, it serves as the mammary gland, which produces and sec ...
").
According to the
WMO
The World Meteorological Organization (WMO) is a specialized agency of the United Nations responsible for promoting international cooperation on atmospheric science, climatology, hydrology and geophysics.
The WMO originated from the Internat ...
International Cloud Atlas
The ''International Cloud Atlas'' or simply the ''Cloud Atlas'', is a cloud atlas that was first published in 1896 and has remained in print since. Its initial purposes included aiding the training of meteorologists and promoting more consisten ...
, ''mamma'' is a cloud supplementary feature rather than a genus, species or variety of cloud. The distinct "lumpy" undersides are formed by cold air sinking down to form the pockets contrary to the puffs of clouds rising through the convection of warm air. These formations were first described in 1894 by
William Clement Ley
William Clement Ley (6 July 1840 - 22 April 1896) was an English clergyman and pioneer meteorologist who studied clouds and examined their dynamics and use in weather forecasting.
Life
Ley was born in Bristol to William Henry Ley who was a headm ...
.
Characteristics
![Cumulonimbus incus with mammatus clouds](https://upload.wikimedia.org/wikipedia/commons/3/32/Cumulonimbus_incus_with_mammatus_clouds.jpg)
Mammatus are most often associated with
anvil cloud
A cumulonimbus incus (Latin ''incus'', "anvil"), also known as an anvil cloud, is a cumulonimbus cloud which has reached the level of stratospheric stability and has formed the characteristic flat, anvil-top shape. It signifies the thunderstor ...
s and also severe thunderstorms. They often extend from the base of a
cumulonimbus
Cumulonimbus (from Latin ''cumulus'', "heaped" and ''nimbus'', "rainstorm") is a dense, towering vertical cloud, typically forming from water vapor condensing in the lower troposphere that builds upward carried by powerful buoyant air currents. ...
, but may also be found under
altostratus
Altostratus is a middle-altitude cloud genus made up of water droplets, ice crystals, 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 usuall ...
, and
cirrus
Cirrus may refer to:
Science
*Cirrus (biology), any of various thin, thread-like structures on the body of an animal
*Cirrus (botany), a tendril
* Infrared cirrus, in astronomy, filamentary structures seen in infrared light
*Cirrus cloud, a typ ...
clouds, as well as volcanic ash clouds.
When occurring in cumulonimbus, mammatus are often indicative of a particularly strong storm. Due to the intensely sheared environment in which mammatus form,
aviators are strongly cautioned to avoid
cumulonimbus
Cumulonimbus (from Latin ''cumulus'', "heaped" and ''nimbus'', "rainstorm") is a dense, towering vertical cloud, typically forming from water vapor condensing in the lower troposphere that builds upward carried by powerful buoyant air currents. ...
with mammatus as they indicate convectively induced turbulence. Contrails may also produce lobes but these are incorrectly termed as mammatus.
Mammatus may appear as smooth, ragged or lumpy lobes and may be opaque or translucent. Because mammatus occur as a grouping of lobes, the way they clump together can vary from an isolated cluster to a field of mammae that spread over hundreds of kilometers to being organized along a line, and may be composed of unequal or similarly-sized lobes. The individual mammatus lobe average diameters of and lengths on average of . A lobe can last an average of 10 minutes, but a whole cluster of mamma can range from 15 minutes to a few hours. They are usually composed of ice, but also can be a mixture of ice and liquid water or be composed of almost entirely liquid water.
True to their ominous appearance, mammatus clouds are often harbingers of a coming storm or other extreme weather system. Typically composed primarily of ice, they can extend for hundreds of miles in each direction and individual formations can remain visibly static for ten to fifteen minutes at a time. While they may appear foreboding they are merely the messengers - appearing around, before or even after severe weather.
Hypothesized formation mechanisms
![Mammatus cloud panorama](https://upload.wikimedia.org/wikipedia/commons/b/bc/Mammatus_cloud_panorama.jpg)
The existence of many different types of mammatus clouds, each with distinct properties and occurring in distinct environments, has given rise to multiple hypotheses on their formation, which are also relevant to other cloud forms.
One environmental trend is shared by all of the formation mechanisms hypothesized for mammatus clouds: sharp
gradient
In vector calculus, the gradient of a scalar-valued differentiable function of several variables is the vector field (or vector-valued function) \nabla f whose value at a point p is the "direction and rate of fastest increase". If the gr ...
s in temperature, moisture and momentum (
wind shear
Wind shear (or windshear), sometimes referred to as wind gradient, is a difference in wind speed and/or direction over a relatively short distance in the atmosphere. Atmospheric wind shear is normally described as either vertical or horizont ...
) across the anvil cloud/sub-cloud air boundary, which strongly influence interactions therein. The following are the proposed mechanisms, each described with its shortcomings:
* The anvil of a
cumulonimbus cloud
Cumulonimbus (from Latin ''cumulus'', "heaped" and ''nimbus'', "rainstorm") is a dense, towering vertical cloud, typically forming from water vapor condensing in the lower troposphere that builds upward carried by powerful buoyant air currents. ...
gradually subsides as it spreads out from its source cloud. As air descends, it warms. However, the cloudy air will warm more slowly (at the
moist adiabatic lapse rate
The lapse rate is the rate at which an atmospheric variable, normally temperature in Earth's atmosphere, falls with altitude. ''Lapse rate'' arises from the word ''lapse'', in the sense of a gradual fall. In dry air, the adiabatic lapse rate is ...
) than the sub-cloud, dry air (at the
dry adiabatic lapse rate
The lapse rate is the rate at which an atmospheric variable, normally temperature in Earth's atmosphere, falls with altitude. ''Lapse rate'' arises from the word ''lapse'', in the sense of a gradual fall. In dry air, the adiabatic lapse rate is ...
). Because of the differential warming, the cloud/sub-cloud layer
destabilizes and
convective
Convection is single or multiphase fluid flow that occurs spontaneously due to the combined effects of material property heterogeneity and body forces on a fluid, most commonly density and gravity (see buoyancy). When the cause of the convec ...
overturning can occur, creating a lumpy cloud-base. The problems with this theory are that there are observations of mammatus lobes that do not support the presence of strong subsidence in the lobes, and that it is difficult to separate the processes of
hydrometeor
In meteorology, precipitation is any product of the condensation of atmospheric water vapor that falls under gravitational pull from clouds. The main forms of precipitation include drizzle, rain, sleet, snow, ice pellets, graupel and hail. ...
fallout and cloud-base subsidence, thus rendering it unclear as to whether either process is occurring.
* Cooling due to
hydrometeor
In meteorology, precipitation is any product of the condensation of atmospheric water vapor that falls under gravitational pull from clouds. The main forms of precipitation include drizzle, rain, sleet, snow, ice pellets, graupel and hail. ...
fallout is a second proposed formation mechanism. As hydrometeors fall into the dry sub-cloud air, the air containing the precipitation
cools
Cools is a Dutch patronymic surname meaning "son of Cool", Cool being an archaic nickname for Nicholas. The name is particularly prominent in the Belgian province of Antwerp. People with the surname include:
* Alexander Cools ( 1941–2013), D ...
due to
evaporation or
sublimation. Being now cooler than the environmental air and unstable, they descend until in static equilibrium, at which point a restoring force curves the edges of the fallout back up, creating the lobed appearance. One problem with this theory is that observations show that cloud-base evaporation does not always produce mammatus. This mechanism could be responsible for the earliest stage of development, but other processes (namely process 1, above) may come into play as the lobes are formed and mature.
* There may also be destabilization at cloud base due to melting. If the cloud base exists near the freezing line, then the cooling in the immediate air caused by melting can lead to convective overturning, just as in the processes above. However, this strict temperature environment is not always present.
* The above processes specifically relied on the destabilization of the sub-cloud layer due to
adiabatic or
latent heat
Latent heat (also known as latent energy or heat of transformation) is energy released or absorbed, by a body or a thermodynamic system, during a constant-temperature process — usually a first-order phase transition.
Latent heat can be underst ...
ing effects. Discounting the
thermodynamical effects of hydrometeor fallout, another mechanism proposes that
dynamics of the fallout alone are enough to create the lobes. Inhomogeneities in the masses of the
hydrometeors
In meteorology, precipitation is any product of the condensation of atmospheric water vapor that falls under gravitational pull from clouds. The main forms of precipitation include drizzle, rain, Rain and snow mixed, sleet, snow, ice pellets, ...
along the cloud-base may cause inhomogeneous descent along the base. Frictional drag and associated eddy-like structures create the lobed appearance of the fallout. The main shortcoming of this theory is that vertical velocities in the lobes have been observed to be greater than the fall speeds of the hydrometeors within them; thus, there should be a dynamical downward forcing, as well.
* Another method, that was first proposed by
Kerry Emanuel
Kerry Andrew Emanuel (born April 21, 1955) is an American professor of meteorology currently working at the Massachusetts Institute of Technology in Cambridge. In particular he has specialized in atmospheric convection and the mechanisms acting t ...
, is called cloud-base detrainment instability (CDI), which acts very much like convective cloud-top
entrainment
Entrainment may refer to:
* Air entrainment, the intentional creation of tiny air bubbles in concrete
* Brainwave entrainment, the practice of entraining one's brainwaves to a desired frequency
* Entrainment (biomusicology), the synchronization o ...
. In CDI, cloudy air is mixed into the dry sub-cloud air rather than precipitating into it. The cloudy layer destabilizes due to evaporative cooling and mammatus are formed.
* Clouds undergo thermal reorganization due to radiative effects as they evolve. There are a couple of ideas as to how radiation can cause mammatus to form. One is that, because clouds radiatively cool (
Stefan–Boltzmann law
The Stefan–Boltzmann law describes the power radiated from a black body in terms of its temperature. Specifically, the Stefan–Boltzmann law states that the total energy radiated per unit surface area of a black body across all wavelengths ...
) very efficiently at their tops, entire pockets of cool, negatively
buoyant
Buoyancy (), or upthrust, is an upward force exerted by a fluid that opposes the weight of a partially or fully immersed object. In a column of fluid, pressure increases with depth as a result of the weight of the overlying fluid. Thus the pr ...
cloud can penetrate downward through the entire layer and emerge as mammatus at cloud-base. Another idea is that as the cloud-base warms due to radiative heating from land surface's longwave emission, the base destabilizes and overturns. This method is valid for only
optically thick clouds. However, the nature of anvil clouds is that they are largely made up of ice, and are therefore relatively optically thin.
*
Gravity waves are proposed to be the formation mechanism of linearly organized mammatus clouds. Indeed, wave patterns have been observed in the mammatus environment, but this is mostly due to gravity wave creation as a response to a convective
updraft
In meteorology, an updraft is a small-scale current of rising air, often within a cloud.
Overview
Localized regions of warm or cool air will exhibit vertical movement. A mass of warm air will typically be less dense than the surrounding regi ...
impinging upon the tropopause and spreading out in wave form over the entirety of the anvil. Therefore, this method does not explain the prevalence of mammatus clouds in one part of the anvil versus another. Furthermore, time and size scales for gravity waves and mammatus do not match up entirely. Gravity wave trains may be responsible for organizing the mammatus rather than forming them.
*
Kelvin–Helmholtz (K–H) instability is prevalent along cloud boundaries and results in the formation of wave-like protrusions (called Kelvin-Helmholtz billows) from a cloud boundary. Mammatus are not in the form of K-H billows, thus, it is proposed that the instability can trigger the formation of the protrusions, but that another process must form the protrusions into lobes. Still, the main downfall with this theory is that K-H instability occurs in a stably
stratified environment, and the mammatus environment is usually at least somewhat
turbulent
In fluid dynamics, turbulence or turbulent flow is fluid motion characterized by chaotic changes in pressure and flow velocity. It is in contrast to a laminar flow, which occurs when a fluid flows in parallel layers, with no disruption between ...
.
*
Rayleigh–Taylor instability
The Rayleigh–Taylor instability, or RT instability (after Lord Rayleigh and G. I. Taylor), is an instability of an interface between two fluids of different densities which occurs when the lighter fluid is pushing the heavier fluid.
Drazin ( ...
is the name given to the instability that exists between two fluids of differing densities, when the denser of the two is atop the less dense fluid. Along a cloud-base/sub-cloud interface, the denser, hydrometeor-laden air could cause mixing with the less-dense sub-cloud air. This mixing would take the form of mammatus clouds. The physical problem with this proposed method is that an instability existing along a static interface cannot necessarily be applied to the interface between two
sheared atmospheric flows.
* The last proposed formation mechanism is that mammatus arise from
Rayleigh–Bénard convection
In fluid thermodynamics, Rayleigh–Bénard convection is a type of natural convection, occurring in a planar horizontal layer of fluid heated from below, in which the fluid develops a regular pattern of convection cells known as Bénard cells. ...
, where differential heating (cooling at the top and heating at the bottom) of a layer causes convective overturning. However, in this case of mammatus, the base is cooled by thermodynamical mechanisms mentioned above. As the cloud base descends, it happens on the scale of mammatus lobes, while adjacent to the lobes, there is a compensating ascent. This method has not proven to be observationally sound and is viewed as generally insubstantial.
This plenitude of proposed formation mechanisms shows, if nothing else, that the mammatus cloud is generally poorly understood.
Gallery
File:Wea02264_-_Flickr_-_NOAA_Photo_Library.jpg, Mammatus clouds over U.S. Air Force Academy, 2004
File:Mammatus over Croatia.jpg, Mammatus clouds over Croatia
, image_flag = Flag of Croatia.svg
, image_coat = Coat of arms of Croatia.svg
, anthem = "Lijepa naša domovino"("Our Beautiful Homeland")
, image_map =
, map_caption =
, capit ...
File:Mammatus clouds NYC.jpg, Mammatus clouds over New York City
New York, often called New York City or NYC, is the most populous city in the United States. With a 2020 population of 8,804,190 distributed over , New York City is also the most densely populated major city in the Un ...
, 2009
File:Mammatus-clouds-Tulsa-1973.png, Mammatus clouds in Tulsa, Oklahoma
Tulsa () is the second-largest city in the state of Oklahoma and 47th-most populous city in the United States. The population was 413,066 as of the 2020 census. It is the principal municipality of the Tulsa Metropolitan Area, a region with ...
, 1973
File:Mammatus-storm-clouds San-Antonio.jpg, Mammatus clouds over San Antonio, Texas
("Cradle of Freedom")
, image_map =
, mapsize = 220px
, map_caption = Interactive map of San Antonio
, subdivision_type = Country
, subdivision_name = United States
, subdivision_type1= State
, subdivision_name1 = Texas
, subdivision_t ...
, 2009
File:Mammatus clouds over San Francisco.jpg, Mammatus Clouds over the Pacific Coast San Francisco
San Francisco (; Spanish for " Saint Francis"), officially the City and County of San Francisco, is the commercial, financial, and cultural center of Northern California. The city proper is the fourth most populous in California and 17th ...
File:Mammatussquawvalley.jpg, Mammatus clouds over Squaw Valley Ski Resort, Olympic Valley, California
Olympic Valley (historically or informally known as Squaw Valley) is an unincorporated area, unincorporated community located in Placer County, California northwest of Tahoe City, California, Tahoe City along California State Route 89, California ...
File:Cirrus-mamma01.jpg, Cirrus mamma
File:Mammatus clouds Milan July.jpg, Mammatus clouds in Milan, Italy
Milan ( , , Lombard: ; it, Milano ) is a city in northern Italy, capital of Lombardy, and the second-most populous city proper in Italy after Rome. The city proper has a population of about 1.4 million, while its metropolitan city ...
, in July 2005 on a very hot, humid day without wind
File:Mammatus clouds 2008-04-01.jpg, Mammatus Clouds in San Francisco, California
San Francisco (; Spanish for " Saint Francis"), officially the City and County of San Francisco, is the commercial, financial, and cultural center of Northern California. The city proper is the fourth most populous in California and 17th ...
File:Mammatus Clouds.png, Mammatus clouds forming in Minnesota
Minnesota () is a state in the upper midwestern region of the United States. It is the 12th largest U.S. state in area and the 22nd most populous, with over 5.75 million residents. Minnesota is home to western prairies, now given over to ...
in 2005
File:Mammatus clouds and crepuscular rays new.jpg, Mammatus clouds and crepuscular rays
Crepuscular rays are sunbeams that originate when the Sun is just below the horizon, during the twilight period. Crepuscular rays are noticeable when the contrast between light and dark is most obvious. Crepuscular comes from the Latin word ...
over San Francisco Bay
File:Mammatus clouds over central NSW.jpg, Aerial photo of mammatus clouds over central New South Wales
)
, nickname =
, image_map = New South Wales in Australia.svg
, map_caption = Location of New South Wales in AustraliaCoordinates:
, subdivision_type = Country
, subdivision_name = Australia
, established_title = Before federation
, es ...
, Australia,
File:Mammatus Clouds Over Mountains.jpg, Mammatus Clouds Over Sierras de Córdoba Mountains, Argentina
Argentina (), officially the Argentine Republic ( es, link=no, República Argentina), is a country in the southern half of South America. Argentina covers an area of , making it the second-largest country in South America after Brazil, th ...
File:Cumulonimbus Mammatus clouds near Salt Lake City.jpg, Mammatus clouds above Big Cottonwood Canyon
Big Cottonwood Canyon is a canyon in the Wasatch Range southeast of Salt Lake City in the U.S. state of Utah. The -long canyon provides hiking, biking, picnicking, rock-climbing, camping, and fishing in the summer. Its two ski resorts, Brig ...
near Salt Lake City
Salt Lake City (often shortened to Salt Lake and abbreviated as SLC) is the capital and most populous city of Utah, United States. It is the seat of Salt Lake County, the most populous county in Utah. With a population of 200,133 in 2020, th ...
, Utah
Utah ( , ) is a state in the Mountain West subregion of the Western United States. Utah is a landlocked U.S. state bordered to its east by Colorado, to its northeast by Wyoming, to its north by Idaho, to its south by Arizona, and to it ...
File:CumulusMammatus2.jpg, Mammatus clouds over Santa Catarina, Brazil
Santa Catarina (, ) is a state in the South Region of Brazil. It is the 7th smallest state in total area and the 11th most populous. Additionally, it is the 9th largest settlement, with 295 municipalities. The state, with 3.4% of the Brazili ...
, following Cyclone Catarina
Hurricane Catarina, or Cyclone Catarina () was an extraordinarily rare South Atlantic tropical cyclone, the only recorded hurricane strength storm on record in the South Atlantic Ocean. Catarina made landfall on South Brazil at peak intensity, ...
.
File:Mammatus clouds Montana MT1.jpg, Cumulus Mammatus clouds between Hamilton Hamilton may refer to:
People
* Hamilton (name), a common British surname and occasional given name, usually of Scottish origin, including a list of persons with the surname
** The Duke of Hamilton, the premier peer of Scotland
** Lord Hamilt ...
and Missoula, Montana
Missoula ( ; fla, label= Séliš, Nłʔay, lit=Place of the Small Bull Trout, script=Latn; kut, Tuhuⱡnana, script=Latn) is a city in the U.S. state of Montana; it is the county seat of Missoula County. It is located along the Clark Fork ...
File:Mammatus Over UCF.jpg, Mammatus clouds over the University of Central Florida
The University of Central Florida (UCF) is a public research university whose main campus is in unincorporated Orange County, Florida. UCF also has nine smaller regional campuses throughout central Florida. It is part of the State University ...
in Orlando, Florida, 2011.
File:Mammatus over Altomünster.jpg, Just before a large thunderstorm in Altomuenster, Bavaria
Bavaria ( ; ), officially the Free State of Bavaria (german: Freistaat Bayern, link=no ), is a state in the south-east of Germany. With an area of , Bavaria is the largest German state by land area, comprising roughly a fifth of the total lan ...
, Germany
File:Mammatus Clouds over Bingley.JPG, Mammatus clouds over Bingley
Bingley is a market town and civil parish in the metropolitan borough of the City of Bradford, West Yorkshire, England, on the River Aire and the Leeds and Liverpool Canal, which had a population of 18,294 at the 2011 Census.
Bingley railwa ...
, UK, following a thunderstorm on 2 November 2013
File:Mammatus-Cap-de-Creus 2014.jpg, Mammatocumulus in Cap de Creus, Girona
Girona (officially and in Catalan , Spanish: ''Gerona'' ) is a city in northern Catalonia, Spain, at the confluence of the Ter, Onyar, Galligants, and Güell rivers. The city had an official population of 103,369 in 2020. Girona is the capital ...
, Spain
, image_flag = Bandera de España.svg
, image_coat = Escudo de España (mazonado).svg
, national_motto = ''Plus ultra'' (Latin)(English: "Further Beyond")
, national_anthem = (English: "Royal March")
, i ...
. Electric atmosphere. June 2014
File:Mammatus Clouds, Austin, Memorial Day 2015.jpg, Mammatus clouds over Austin, Texas
Texas (, ; Spanish: ''Texas'', ''Tejas'') is a state in the South Central region of the United States. At 268,596 square miles (695,662 km2), and with more than 29.1 million residents in 2020, it is the second-largest U.S. state by ...
, after the torrential Memorial Day floods of 2015.
File:MammatusCloudsAnkita.jpg, Mammatus Clouds over Hoshiarpur
Hoshiarpur () is a city and a municipal corporation in Hoshiarpur district in the Doaba region of the Indian state of Punjab. It was founded, according to tradition, during the early part of the fourteenth century. In 1809, it was occupied b ...
May 20, 2016, Punjab, India
File:Mammatus Norwich UK 2015 05 24.jpg, Mammatus Clouds observed in Norwich Norfolk, UK, 2015/05/24 just before sunset in the west moving east. Duration 17 minutes. Calm weather. No rain, 19 Celsius.
File:Mammatus clouds regina sk june 2012.JPG, Strikingly regular mammatus clouds on June 26, 2012 in Regina, Saskatchewan, following a severe storm warning and tornado watch.
File:Mammatus clouds in Lithuania.jpg, Mammatus clouds in Lithuania, 2016
File:Mammatus-cloud.jpg, Mammatus clouds formation in Coimbatore, Tamil Nadu
Coimbatore, also spelt as Koyamputhur (), sometimes shortened as Kovai (), is one of the major metropolitan cities in the Indian state of Tamil Nadu. It is located on the banks of the Noyyal River and surrounded by the Western Ghats. Coimbat ...
India - 2019
File:Berlin Mammatus.jpg, Mammatus clouds formation in Berlin
Berlin ( , ) is the capital and List of cities in Germany by population, largest city of Germany by both area and population. Its 3.7 million inhabitants make it the European Union's List of cities in the European Union by population within ci ...
Germany 2021
File:Mammatus clouds over New Jersey.jpg, Mammatus clouds over Englewood Cliffs
Englewood Cliffs is a borough in Bergen County, in the U.S. state of New Jersey, whose population at the 2010 United States census was 5,281.[New Jersey
New Jersey is a state in the Mid-Atlantic and Northeastern regions of the United States. It is bordered on the north and east by the state of New York; on the east, southeast, and south by the Atlantic Ocean; on the west by the Delaware ...]
2021.
File:Mammatus-guthrie.jpg, center, alt=Mammatus clouds in the evening near Guthrie, Oklahoma on 2 May 2022, Mammatus clouds in the evening near Guthrie, Oklahoma on 2 May 2022
File:Mammatus Clouds - Squirrel Hill Pennsylvania - 6 16 22.jpg, alt=Picture taken of Mammatus Clouds in Squirrel Hill (Pittsburgh) Pennsylvania on June 16th 2022 around 9:02pm., Mammatus clouds at 9:02pm near Pittsburgh, Pennsylvania
Pittsburgh ( ) is a city in the Commonwealth of Pennsylvania, United States, and the county seat of Allegheny County. It is the most populous city in both Allegheny County and Western Pennsylvania, the second-most populous city in Pennsylva ...
on June 16th 2022
File:Mammatussandefjord.jpg, Mammatus cloud in Sandefjord, Norway
Sandefjord () is a city and the most populous municipality in Vestfold og Telemark county, Norway. The municipality of Sandefjord was established on 1 January 1838. The municipality of Sandar was merged into Sandefjord on 1 January 1969. On 1 ...
on July 15th 2022 around 20:43
References
External links
Forming Mammatus Clouds Time Lapse VideoMammatus Clouds sagging pouch-like structures*
Mammatus Clouds over St Albans, Hertfordshire, UK on 12 August 2008at the BBC News web site. 21 August 2008
{{DEFAULTSORT:Mammatus cloud
Accessory clouds
Cumulus