madohora Re: ZJAWISKA ATMOSFERYCZNE 14.07.21, 23:52 There are several ways in which sea ice algal blooms are thought to start their annual cycle, and hypotheses about these vary depending on water column depth, sea ice age, and taxonomic group. Where sea ice overlays deep ocean, it is proposed that cells trapped in multiyear ice brine pockets are reconnected to the water column below and quickly colonize nearby ice of all ages. This is known as the multiyear sea ice repository hypothesis. This seeding source has been demonstrated in diatoms, which dominate sympagic blooms. Other groups, such as the dinoflagellates, which also bloom in the spring/summer, have been shown to maintain low cell numbers in the water column itself, and do not primarily overwinter within the ice. Where sea ice covers ocean that is somewhat shallower, resuspension of cells from the sediment may occur Odpowiedz Link
madohora Re: ZJAWISKA ATMOSFERYCZNE 14.07.21, 23:53 Climate change and warming of Arctic and Antarctic regions have the potential to greatly alter ecosystem functioning. Decreasing ice cover in polar regions is expected to lessen the relative proportion of sea ice algae production to measures of annual primary production.[23][24] Thinning ice allows for greater production early in the season but early ice melting shortens the overall growing season of the sea ice algae. This melting also contributes to stratification of the water column that alters the availability of nutrients for algae growth by decreasing the depth of the surface mixed layer and inhibiting the upwelling of nutrients from deep waters. This is expected to cause an overall shift towards pelagic phytoplankton production.[24] Changes in multiyear ice volume[25] will also have an impact on ecosystem function in terms of bloom seeding source adjustment. Reduction in MYI, a temporal refugia for diatoms in particular, will likely alter sympagic community composition, resulting in bloom initialization that derives from species that overwinter in the water column or sediments instead. Odpowiedz Link
madohora Re: ZJAWISKA ATMOSFERYCZNE 14.07.21, 23:53 Because sea ice algae are often the base of the food web, these alterations have implications for species of higher trophic levels.[15] The reproduction and migration cycles of many polar primary consumers are timed with the bloom of sea ice algae, meaning that a change in the timing or location of primary production could shift the distribution of prey populations necessary for significant keystone species. Production timing may also be altered by the melting through of surface melt ponds to the seawater below, which can alter sea ice algal habitat late in the growing season in such a way as to impact grazing communities as they approach winter Odpowiedz Link
madohora Re: ZJAWISKA ATMOSFERYCZNE 14.07.21, 23:53 The production of DMSP by sea ice algae also plays an important role in the carbon cycle. DMSP is oxidized by other plankton to dimethylsulfide (DMS), a compound which is linked to cloud formation. Because clouds impact precipitation and the amount of solar radiation reflected back to space (albedo), this process could create a positive feedback loop. Cloud cover would increase the insolation reflected back to space by the atmosphere, potentially helping to cool the planet and support more polar habitats for sea ice algae. As of 1987, research has suggested that a doubling of cloud-condensation nuclei, of which DMS is one type, would be required to counteract warming due to increased atmospheric CO2 concentrations Odpowiedz Link
madohora Re: ZJAWISKA ATMOSFERYCZNE 14.07.21, 23:54 Sea ice plays a major role in the global climate. Satellite observations of sea ice extent date back only until the late 1970s, and longer term observational records are sporadic and of uncertain reliability.[30] While terrestrial ice paleoclimatology can be measured directly through ice cores, historical models of sea ice must rely on proxies. Odpowiedz Link
madohora Re: ZJAWISKA ATMOSFERYCZNE 14.07.21, 23:54 Organisms dwelling on the sea ice eventually detach from the ice and fall through the water column, particularly when the sea ice melts. A portion of the material that reaches the seafloor is buried before it is consumed and is thus preserved in the sedimentary record. Odpowiedz Link
madohora Re: ZJAWISKA ATMOSFERYCZNE 14.07.21, 23:54 There are a number of organisms whose value as proxies for the presence of sea ice has been investigated, including particular species of diatoms, dinoflagellate cysts, ostracods, and foraminifers. Variation in carbon and oxygen isotopes in a sediment core can also be used to make inferences about sea ice extent. Each proxy has advantages and disadvantages; for example, some diatom species that are unique to sea ice are very abundant in the sediment record, however, preservation efficiency can vary. Odpowiedz Link
madohora Re: ZJAWISKA ATMOSFERYCZNE 14.07.21, 23:55 Algae also occur on terrestrial ice sheets and glaciers. The species found in these habitats are distinct from those associated with sea ice because the system is freshwater. Even within these habitats, there is a wide diversity of habitat types and algal assemblages. For example, cryosestic communities are specifically found on the surface of glaciers where the snow periodically melts during the day. Research has been done on glaciers and ice sheets across the world and several species have been identified. However, although there seems to be a wide array of species they have not been found is equal amounts. The most abundant species identified on different glaciers are Ancyonema nordenskioldii and Chlamydomonas nivalis Odpowiedz Link
madohora Re: HYBRYDOWE ZAĆMIENIE SŁOŃCA 14.07.21, 23:55 The rate of glacier melt depends on the surface albedo. Recent research has shown the growth of algae darkens local surface conditions, decreasing the albedo and thus increases the melt rate on these surfaces.Melting glaciers and ice sheets have been directly linked to increase in sea level rise. The second largest ice sheet is the Greenland Ice Sheet which has been retreating at alarming rates. Sea level rise will lead to an increase in both frequency and intensity of storm events Odpowiedz Link
madohora Re: ZJAWISKA ATMOSFERYCZNE 14.07.21, 23:56 On enduring ice sheets and snow pack, terrestrial ice algae often color the ice due to accessory pigments, popularly known as "watermelon snow". The dark pigments within the structure of algae increases sunlight absorption, leading to an increase in the melting rate.[33] Algae blooms have been shown to appear on glaciers and ice sheets once the snow had begun to melt, which occurs when the air temperature is above the freezing point for a few days. The abundance of algae changes with the seasons and also spatially on glaciers. Their abundance is highest during the melting season of glaciers which occurs in the summer months.[33] Climate change is affecting both the start of the melting season and also the length of this period, which will lead to an increase in the amount of algae growth. Odpowiedz Link
madohora Re: ZJAWISKA ATMOSFERYCZNE 14.07.21, 23:56 As the ice/snow begins to melt the area the ice covers decreases which means a higher portion of land is exposed. The land underneath the ice has a higher rate of solar absorption due to it being less reflective and darker. Melting snow also has lower albedo than dry snow or ice because of its optical properties, so as snow begins to melt the albedo decreases, which results in more snow melting, and the loop continues. This feedback loop is referred to as the Ice–albedo feedback loop. This can have drastic effects on the amount of snow melting each season. Algae plays a role in this feedback loop by decreasing the level of albedo of the snow/ice. This growth of algae has been studied but its exact effects on decreasing albedo is still unknown. Odpowiedz Link
madohora Re: ZJAWISKA ATMOSFERYCZNE 14.07.21, 23:56 The Black and Bloom project is conducting research to determine the amount algae are contributing to the darkening of the Greenland Ice Sheet, as well as algae's impact on the melting rates of the ice sheets. It is important to understand the extent to which algae is changing the albedo on glaciers and ice sheets. Once this is known, it should be incorporated into global climate models and then used to predict sea level rise. Odpowiedz Link
madohora Re: HYBRYDOWE ZAĆMIENIE SŁOŃCA 14.07.21, 23:57 Śnieżyca, zawieja śnieżna, burza śnieżna, zadymka – gwałtowny, obfity opad śniegu z towarzyszącym mu silnym wiatrem Odpowiedz Link
madohora Re: ZJAWISKA ATMOSFERYCZNE 14.07.21, 23:58 Podczas zawiei śnieg praktycznie nie opada na ziemię, a jest niesiony przez wiatr. Widoczność jest często ograniczona do poniżej 200 m co może sprzyjać wypadkom na drogach. Przy sprzyjających do tego warunkach mogą wystąpić wyładowania atmosferyczne wtedy mowa o burzy śnieżnej Odpowiedz Link
madohora Re: ZJAWISKA ATMOSFERYCZNE 14.07.21, 23:58 Podczas silnej śnieżycy na skutek zgniatania, tarcia kryształków lodu dochodzi do uwolnienia ładunków elektrycznych i elektryzowania się śniegu. Maksymalnie uwolnione ładunki mogą dochodzić do 0,2 nC/mg. Potencjał pola elektrostatycznego generowanego przez burzę śnieżną może dochodzić do 6–10 kV/m lub więcej. W związku z tym podczas śnieżyc obserwowane są elektrometeory. Wyjątkowo duży gradient pola elektrostatycznego obserwowany przy silnych śnieżycach występujących przy niskich temperaturach i niskiej wilgotności powietrza (suchy, drobny śnieg), prowadzi do wygenerowania znacznych ładunków elektrycznych obserwowanych postaci zakłóceń radiowych lub zjawisk świetlnych oraz wzrostu ryzyka awarii sieci elektrycznej. Odpowiedz Link
madohora Re: ZJAWISKA ATMOSFERYCZNE 14.07.21, 23:59 Generowana w ten sposób energia elektryczna ze względu na niewielką gęstość elektryczną burzy śnieżnej mogłaby zostać wykorzystana do zasilania urządzeń jedynie o niewielkim poborze energii Odpowiedz Link
madohora Re: HYBRYDOWE ZAĆMIENIE SŁOŃCA 15.07.21, 00:00 Sněhová bouře (též: vánice) je meteorologická událost s převažujícími silnými sněhovými srážkami doprovázená silným větrem a náhlým poklesem teplot. Sněhová bouře není vždy spojena jen se zimní sezónou, ale může se objevit i na jaře či na podzim. Odpowiedz Link
madohora Re: ZJAWISKA ATMOSFERYCZNE 15.07.21, 00:00 V některých případech může docházet k tomu, že na zemský povrch dopadá voda v kapalné fázi, která po dopadnutí na předmět okamžitě mrzne, čímž umožňuje vzniknout ledové krusty na předmětech. V takovém případě hovoříme o ledovce. Odpowiedz Link
madohora Re: ZJAWISKA ATMOSFERYCZNE 15.07.21, 00:00 Během sněhové bouře napadne na zemský povrch velké množství sněhu, který způsobuje následné kalamitní situace v oblasti jako kolaps dopravy, přetrhání elektrického vedení a nebo polomy v lesích. Uvádí se, že přibližně 2 cm vody jsou schopny se přeměnit ve 20 cm sněhové pokrývky. Odpowiedz Link
madohora Re: ZJAWISKA ATMOSFERYCZNE 15.07.21, 00:01 Velmi silná a prudká sněhová bouře přecházející až ve vichřici se nazývá blizard. Odpowiedz Link
madohora Re: HYBRYDOWE ZAĆMIENIE SŁOŃCA 15.07.21, 00:02 Als Schneesturm bezeichnet man einen Sturm mit heftigem Schneefall. Schneestürme sind typischerweise Winterstürme, von Tiefdruckgebieten angetriebene Starkwindereignisse bei gleichzeitigem Einbruch von polarer Kaltluft. Außerdem sind sie im Hochgebirge der Regelfall, wo sie auch im Sommer auftreten können. Odpowiedz Link
madohora Re: ZJAWISKA ATMOSFERYCZNE 15.07.21, 00:02 Schneestürme sind charakteristisch für bestimmte Weltgegenden und haben dort spezielle Namen: Blizzard – Nordamerika, Antarktis und Lappland Purga – Zentralasien Yalca – Anden im Norden Perus Winter-Buran – Kasachstan und Westsibirien Odpowiedz Link