Clouds 101: Mammatocumulus (Mammatus Clouds)

3/04/2013


Mammatocumulus or mammatus clouds are very curious looking clouds which I have seen myself on two occasions. Once in the dawn during spring and once in the afternoon, during the spring/summer transition. Clouds that I've seen are the mildest possible variation of mammatus clouds and not as intense as they look on the following pictures. I can also say that it's most definitely true that they appear, perfectly formed for about 10-15 minutes and than they disperse into surrounding clouds. I also made some snapshots the second time I've spotted them but, unfortunately, I haven't saved them. They were not as impressive as the ones I've borrowed from other sites to show you but quite a sighting nevertheless. If I ever get the chance to spot them again, I will gladly share my photos with you. Mammatus clouds form in sinking air and that's one of the things that makes them stand apart from most clouds which form in rising air. When you notice a mammatus cloud (or a cluster) you actually see a cloud bottom. Normal cloud bottoms are flat. This is because moist warm air that rises and cools will condense into water droplets at a specific temperature, which usually corresponds to a very specific height. As water droplets grow, an opaque cloud forms. Under some conditions, however, cloud pockets can develop that contain large droplets of water or ice that fall into clear air as they evaporate. Such pockets may occur in turbulent air near a thunderstorm. Although mammatus most frequently form on the underside of a cumulonimbus, they can develop underneath cirrocumulus, altostratus, altocumulus, stratocumulus and volcanic ash clouds. Mammatus clouds do not produce severe weather. However, they are associated with big towering cumulonimbus clouds because they are usually found on the underside of an anvil cloud. The reason some people think Mammatus clouds mean severe weather is coming, is because they often appear before a strong storm moves in. They are also often found after a storm rolls through. In fact, mammatus are usually seen after the worst of a thunderstorm has passed. When these clouds do occur with cumulonimbus, they are generally an indicator of a particularly strong storm or a possible tornado. Intense wind shear in cumulonimbus clouds that have mammatus make it dangerous for aircraft to enter these clouds. Mammatus clouds are a cellular pattern of pouches hanging underneath the base of a cloud. They may be smooth or have ragged, lumpy lobes. These clouds can be opaque or semitransparent. Mammatus frequently occur as a grouping of lobes, so the way they clump together can vary. Some can be an isolated cluster or a field of mammatus can spread over hundreds of kilometers. They can be organized in a line or a jagged slash across the sky composed of unequal or similarly-sized lobes. The average diameter of a lobe is 1–3km. A lobe usually lasts about 10 minutes, but a cluster can remain up to a few hours. They usually are composed of ice, but can be a mixture of ice and liquid water or be composed entirely liquid water. The name of the clouds refers to the fact that their shape resembles the breasts of a woman.Oh, my. Such cheeky clouds these are.

Mammatocumulus ili mammatus oblaci su oblaci dosta interesantnog izgleda koje sam i sama osmotrila u dvije prilike. Jednom je bilo pred zoru u proljece a drugi put u rano poslijepodne, tokom prelaznog perioda iz proljeca na ljeto. Oni koje sam opazila su najslabije izrazena vrsta mammatus oblaka i definitivno nisu ispoljenih karakteristika u jednakom intenzitetu kao na slikama koje cete vidjeti. Takodjer mogu reci da je sigurno istina da kada se pojave u najcistijoj formi, taj period potraje oko 10-15 minuta nakon cega se stope sa okolnim oblacima. Drugom prilikom kada sam ih opazila sam i napravila par fotki ali ih nazalost nisam spasila. Nisu bile impresivan prizor kao slike koje sam posudila sa drugih stranica da vam ih pokazem ali su bez obzira na to bili itekako zanimljiv prizor. Ako mi se ponovo pruzi prilika da ih osmotrim, te slike cu rado da podijelim sa vama. Mammatus oblaci se formiraju u zraku koji ponire i to je jedna od karakteristika po kojoj se razlikuju od vecine oblaka koji inace nastaju u zraku koji ima vertikalno strujanje. Ako opazite mammatus oblak (ili skupinu njih) vi ustvari gledate bazu oblaka. Inace su baze oblaka ravne iz razloga sto se vlazan i topao zrak podize i hladi na visini te kondenzacijom se pretvara u vodene kapljice pri odredjenim temperaturama a sve se to odvija na specificnim visinama. Kako vodene kapljice rastu, formira se neproziran oblak. Ipak pod odredjenim uvjetima se razviju i "dzepovi" oblaka koji sadrze jako velike kapljice vode ili leda koje upadaju u cist zrak dok isparavaju. Takvi dzepovi se mogu pojaviti u turbulentnom zraku u blizini oluje. Iako se mammatus oblaci cesto formiraju u podnozju kumulonimbus oblaka (olujnih oblaka), isto tako se mogu formirati i ispod cirokumulusa, altostratusa, altokumulusa, stratokumulusa i oblaka nastalih vulkanskom prasinom. Mammatus oblaci sami ne izazivaju opasne vremenske prilike. Ipak se cesto povezuju sa kumulonimbusima (CB) jer su cest prizor pri bazi kumulonimbusa i razlog iz kojeg ljudi smatraju da pojava mammatus oblaka znaci da oluja dolazi jeste bas spomenuto formiranje u podnozju CB-a. Iako se nerijetko pojavljuju i nakon sto olujno vrijeme prodje. Stovise, mammatus oblaci se pojavljuju kada najintenzivniji i najopasniji dio olujnog vremena prodje. Kada su vidjeni u kombinaciji sa kumulonimbusom, generalno se smatraju indikatorom da ce uslijediti posebno jaka oluja ili moguci tornado. Intenzivno smicanje vjetra unutar kumulonimbusa koje prate mammatusi predstavlja veliku opasnost za avione ako udju u ove oblake. Mammatus oblaci su vrecaste formacije u celijskom obliku koje vise ispod baze oblaka. Mogu biti glatke oblacne polukruzne rese ili iskrzane rese pune ispupcenja. Mammatusi se cesto pojavljuju u skupinama i nacin na koji su grupirani moze varirati. Neki su izolirana grupica dok drugi mogu biti polje mammatusa koje se prostire na stotine kilometara. Prosjecan promjer jedne polulopte je 1-3 kilometra. Ta polulopta moze da traje otprilike 10 minuta ali se grupacija polulopti moze odrzati i par sati. Najcesce se sastoje od leda ali mogu biti mjesavina leda i vode ili da su potpuno sastavljeni od vode. Ime oblaka se odnosi na cinjenicu da im oblik podsjeca na zenske grudi. Kako su samo bezobrazni ovi oblacici.

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