Meteorological Phenomena: Frost Flowers (Sea Ice)

Last time I have started a new weather-related edition of posts under the oh-so-creative name; Meteorological Phenomena. Previously, I have presented frost flowers in their form present on land. Since there is a second type of these hydrometeors, it would be more than fitting to continue with their sea bound counterpart. Just to be clear on what hydrometeors are – any product of condensation or sublimation of atmosphere vapor, whether formed in free atmosphere or at the Earth's surface; also any water particles blown by the wind from the Earth's surface.

Prosli put sam zapocela novi rubriku koja se temelji na vremenskim pojavama i koja je kreativno nazvana “Meteoroloski Fenomeni”. Tom prilikom sam predstavila zaledjeno cvijece koje je vezano za kopno. Posto postoji jos jedna vrsta ovih hidrometeora, bilo bi prikladno nastaviti rubriku sa vrstom zaledjenog cvijeca vezanog za morski led. Cisto da budemo sigurni kako smo savladali sta su hidrometeori – svaki produkt kondenzacije ( fazni prijelaz iz gasovitog agregatnog stanja u tecno ) ili sublimacije ( tvar iz cvrstog agregatnog stanja prelazi u gasovito stanje ), bez obzira da li se desila u slobodnoj atmosferi ili na povrsini zemlje; isto ukljucuje i bilo koje cestice vode koje nanese vjetar sa povrsine zemlje.

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Sea ice is apparently more interesting than one would think on a first glance. And instead of being a uniformly smooth sheet of ice, it is a complex surface. It also blossoms. Blossoms? Yes, well, at least it looks like it is covered with many newly sprouted flowers. How, why, when and where? Frost flowers (sea ice kind) are actually ice crystals commonly found growing on young sea ice and thin lake ice. These delicate ice structures which seem like huge snow-flakes (they are 3-4cm big in diameter) hide a few secrets inside and the way they are formed is quite interesting as well. Frost flowers “blossom” on forementioned thin and new ice in the Arctic and Antarctic Ocean and only under certain conditions. They are quie needy. 

Morski led se ispostavilo da je mnogo zanimljiviji nego sto bi pomislili na prvi pogled. Umjesto da se radi o jednolicno glatkom sloju leda, on je kompleksna povrsina. Takodjer cvjeta. Cvjeta? Na neki nacin jer djeluje kao da je prekriven svjeze propupalim cvijecem. Kako, zasto, kada i gdje? Ova vrsta zaledjenog cvijeca su ustvari ledeni kristali koji su uobicajeno vidjeni kako rastu na svjeze formiranom morskom ledu i tankom jezerskom ledu. Ove njezne, delikatne strukture koje izgledaju kao velike snjezne pahulje (narastu otprilike 3-4cm u rasponu) u sebi sakrivaju i neke tajne a nacin na koji nastaju je takodjer zanimljiv. Zaledjeno cvijece “cvjeta” na spomenutom tankom, svjeze formiranom ledu preko Arktickog i Antarktickog okeana i samo pod odredjenim uvjetima. Prilicno su zahtjevni.

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Calm wind and very cold air but the catch is that there must be a huge difference in temperature between air and the underlying ice. Air must be appox -22°C cold. And how this works is that the dryness of the very cold air draws out moisture right off tiny bumps in the ice. Those tiny, tiny bits of ice change directly from a solid to gas, completely bypassing the liquid stage. The air gets supersaturated with water vapour and it cannot keep all that excess water vapour in. So when it touches ice crystals (sticking out of the water or simply floating in the air), it immediately turns back to ice. That way more ice gets created to piece together these feathery blossoms. 

Miran vjetar i mnogo hladan zrak su potrebni ali “caka” je u tome sto je neophodno da postoji znatna razlika u temperaturi zraka i leda. Zrak mora biti cca -22°C. Sve funkcionise tako sto suhoca veoma hladnog zraka izvuce vlagu sa sicusnih uzdignuca na povrsini leda. Ti sicusni komadici leda prelaze direktno iz cvrstog u gasovito stanje, u potpunosti preskacuci tecnu fazu. Zrak postaje prezasicen vodenom parom i ne moze u sebi da zadrzi taj visak. Tako da kada dotakne ledene kristale (one koji vire iz leda ili koji plutaju u zraku), momentalno se ponovo pretvara u led. Na taj nacin se sve vise leda stvara koji zajedno tvori ove pernato njezne pupoljke.

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It is thought that as the poles warm, more open sea will turn to thin ice in winter thus more of frost flowers will appear Another curious thing about frost flowers is that they are extremely salty. It contains nearly three times more saline than sea water. Inside of them, salt and marine bacteria are trapped. Approx one million of bacteria. 

Smatra se da kako se polovi budu zagrijavali, sve vise ce se povrsine otvorenog mora da se pretvara u tanak led te ce tako biti sve vise zaledjenog cvijeca. Jos jedan kuriozitet vezan za ovo ledeno cvijece jeste to da je izuzetno slano. Trostruko je veceg saliniteta od same morske vode. Unutar njih su zatocene sol i morske bakterije koje se mjere do miliona. 

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