How to create an aurora borealis effect

Weather in the Arctic

The Weather events in the Arctic is rich in variety and is largely shaped by wind and ocean currents, the arrangement of mountain ranges and the shape of the subsurface (land, sea, ice). That's the average lowest cloud cover for example on the Mainland Nunavuts and those north of it Ice islands as well as in north and Northeast Greenland to be expected where the closed pack ice cover of the Arctic Ocean, about three meters thick, still shows the greatest resistance and thus gives the Arctic Ocean a dry continental influence. The weather here is particularly poor in clouds from November to May, when the ice cover stretches as far as the mainland coast of Nunavut for several months. The result are exceptionally high values ​​of the Sunshine duration in late winter and spring, which in parts Ellesmere Islands in May even on average 500 hours exceeds (that is up to 16.5 hours / day) and thus probably marks the highest sunshine duration of a month on earth. Such a high value cannot be achieved in the subtropical desert regions, for example, because the available day length is simply too short even in summer. In contrast, regions with moist sea air are characterized by warm sea currents, as can be found on the year-round ice-free coasts of Norway and Iceland as well as in the area of ​​the Svalbard archipelago, at least on the west coast, but also Franz-Josef-Land, Nowaya Zemlya and the southeast / South of Greenland (where the Iceland Depression was formed) by a right high cloud cover out. In doing so, Iceland, in the southeast and South Greenland as in Northern Norway also the largest amounts of precipitation the Arctic, which in these regions is extensive 800mm per year and even more than double that in individual areas. In contrast, other regions of the Arctic are extremely dry. In the north of Alaska, Yukon, the Northwest Territories and on the mainland Nunavuts, but also in the Beaufort Sea and on the Canadian Ice Islands (except in the south-eastern half of Baffinland) and in the north-west and north of Greenland, in Franz Josef Land, in Central and eastern Siberia (except for the extreme eastern tip) and north of it in the Laptev and East Siberian Seas far less than 300mm of rainfall per year achieved, being in the extreme Northwest Greenland and on the northern ice islands of Canada often not even 100mm a year getting together.

So while falling precipitation is not really a productive event in considerable parts of the Arctic, settled precipitation can often be observed in some places. Especially from Mid-June to mid-September are partly extensive Fog and high fog banks above arctic seas a quite typical phenomenon, especially in areas with drift ice or cold open sea, with 80-95% of all summer days being cloudy in some of these regions. But also several Coastal areas are from fog affected, especially im June and July. During these months, the relatively strong horizontal temperature gradient between an already snow-free and therefore optimally heated country has the most significant effect compared to seawater that is already open but still very cold. This leads to a pronounced landward air flow of moist sea air (sea breeze), which condenses into fog and is brought to the coastal area in this form (advection fog, cold water fog, up to 15-20 days per summer month). Since there is then often a low-lying inversion produced by the cold sea, further air mass transport upwards is prevented. in the autumn then the slope increases Sea smoke to, a form of mist (mixed mist, warm water mist), which preferably forms over warm water surfaces when the overlying moist air condenses in the surrounding air mass, which has already cooled down due to the coming winter cold. Sea smoke can sometimes spread over a large area and take on the character of a blanket of fog. in the Deep and late winter Fog is rare in the Arctic. But when it is very cold it can be in the interior of the country in hollows or basins or along rivers in the form of flat Ice fog Occasionally encountered from sublimated water vapor.

The Temperatures in the Arctic are low. The reason for this is mainly to be found in the considerable radiation deficit or even the complete absence of short-wave solar radiation in the autumn and winter days. In addition, due to the relatively low height of the sun, the irradiation is not productive even in spring and summer and is also reflected to a not inconsiderable proportion due to the reflective effects of bright snow, glacier and sea ice surfaces. Among other things, this leads to a fascinating peculiarity of the high latitudes, according to which far in the north (low solar height), especially above the Arctic Ocean, the temperature does not rise at all in the sunshine in spring or early summer when a deep cloud cover breaks up, but often even recedes. This is because the snow surfaces (albedo 0.75-0.85), which are still relatively light at this time of year, reduce the entry of short-wave solar radiation to such an extent that the loss of long-wave cloud radiation caused by the cloud dissolution cannot be compensated for at all. The Arctic is coldest in Deep winter in Medium- and East Siberia as well as in Inland Greenlandwhere even Monthly mean temperatures to under -45 ° C decrease and absolute lows of less than -65 ° C have already occurred. Only in winter it is relatively mild south and West Iceland, where the Averages around 0 ° C lie. in the summer however, reach individual areas of the Russian Arctic on the coast to White sea (European Russia) and on Lower Lena (Central Siberia) also warm Monthly mean temperatures at about 15 ° C with average daily maximum temperatures, which even barely exceed 20 ° C. At that time it is in the Ice center of Greenland coolest with one Monthly mean under -10 ° C. The daily temperature variations (i.e. the differences between daily low values ​​and daily high temperatures) are usually rather low in the Arctic and only take on somewhat more significant values ​​in places in the interior of the country when the air is dry, especially in spring. However, in regions that have access to different types of air masses, large temperature jumps can occur in a relatively short time. For example, the supply of mild sea air can resolve a flat but pronounced inversion just as quickly as, conversely, a strong ice-cold continental wind current can displace mild air and thus initiate a sudden drop in temperature, which can easily reach more than 20 ° C.

wind So influences the weather in the Arctic and it can be traced back to various causes. Large-scale, strong winds develop above all in the vicinity of pronounced low pressure areas such as the Iceland lows, which due to the permanently maintained temperature contrast between the cold Greenlandic land / ice mass and the warm North Atlantic ocean current (foothills of the Gulf Stream) again and again approximately in the southeast or South Greenland or near Iceland are formed. These lows then migrate mostly east and northeast and, especially in the colder seasons, often reach over the Norwegian sea until the Barents Sea and sometimes even penetrate them Kara lake in front of or they stay west of it and reach the Greenland lake. In extreme cases, arctic cold air, which passes through seawater kept warm by ocean currents, can become so unstable that a full-blown air polar winter cyclones developed with a diameter of some 100km. Similar to the large tropical cyclones, this can even be equipped with a cloud-free "eye" in the center and only dissolve again when it falls on land or over sea ice surfaces. In summer, however, low pressure areas also form over the Hudson Bay and the adjacent Ice islands of Nunavuts as well as extensive along the North coast of Eurasia in noteworthy numbers, because after the rapid melting of the mostly only small amounts of snow, the land can warm up quickly while the Arctic Ocean remains relatively cool and thus a temperature contrast is created that is favorable for the development of low pressure. Some of these lows then often shift northward and slowly move over the area until autumn central arctic ocean. Away from the low pressure areas, however, strong winds can also arise on elongated hills or mountain ranges if the current cannot overcome them directly due to a striking inversion ("Barrier Jet"). Even in narrow crevices, for example between islands, air movement can sometimes be accelerated enormously and at the exit of the crevice it can also reach hurricane strengths, such as occurs with north winds between Ellesmere Island and northwest Greenland ("Gap Wind"). And the discharge of large amounts of cold air (katabatic wind) from the high inland ice (up to 3230m above sea level) to the east coast of Greenland has a dangerous effect ("Piteraq"), especially if there is a low pressure area near the coast, which really sets the circulation going. But wind in the Arctic does not always have to be expected. Especially in winter, it is often the calm of a clear night in the interior of the country that enables the formation of such icy cold-air lakes in the first place.

Iceland, 08/31/2004
Iceland, 09/01/2004

As unchangeable as this description of Arctic weather events may appear, it should not hide the fact that the conditions have now started to change significantly. Because it will be a dramatic one in the Arctic Climate change of unprecedented proportions. The temperatures increase unimaginably significantly with deviations from long-term monthly mean values, which are sometimes more than 10 ° C. More and more often rain occurs instead of snowfall, even in winter and sometimes reaching high latitudes. Glaciers are melting and sea ice cover is decreasing so rapidly that the possibility is already being considered that the Arctic Ocean could be completely ice-free in late summer and early autumn in the near future. This has an enormous impact on fauna and flora and ultimately also on us humans. This does not mean the supposedly positive effect of a navigable north-east and north-west passage, but the clearly negative effect that the natural cooling of our earth is gradually lost. It is already so warm today that the immense ice sheet of Greenland would probably not be able to build up again if it were completely removed. And the sea ice of the Arctic Ocean, which melts every summer and has to be formed anew in winter, can no longer regenerate completely even in colder winters because annual ice is significantly less stable than the multi-year compact ice cover of earlier times. When the large ice masses of the polar regions disappear, the earth as a whole becomes darker and thus increasingly carries more short-wave solar radiation, which is no longer reflected as efficiently, into its system (Ice albedo feedback). But there are also other feedback effects. Warm open seawater also generates more water due to its increased evaporation rate and the degradation of thermodynamic stability polar depressionswhose associated storms can break up the Arctic sea ice cover even further. In addition, the increasing Meridionality the large-scale atmospheric circulation (as a result of the decreasing global temperature contrasts) an increasing influx of warm air masses from the south. However, this also means that more soot from industrial areas reaches the Arctic and increases the amount of soot that is already caused by growing in-situ tourism pollution and darkening the Snow surfaces. The consequences of the feedback are therefore far-reaching and at some point may no longer be reversible. Therefore, climate and nature protection is an indispensable necessity for the Arctic natural region. The The Arctic and its nature must be protected, Fauna and flora, air and water and the climate of this unique natural region must be preserved, for us humans !!!

Andreas Pfoser, October 6, 2019