Winter 2014/2015 begins to take shape on the Eurasian heaths, first snow in Novosibirsk while Ojmjakon breaks -25 ° C

Winter 2014/2015 begins to take shape on the Eurasian heaths, first snow in Novosibirsk while Ojmjakon breaks -25 ° C

Note the marked extension of the snowpack (fresh snow) over most of the Siberian sector, with a considerable extension of the areas subject to the "Albedo" effect (credit NOAA)

Winter 2014/2015 begins to take shape, launching the first signs of the season, with the progressive cooling of the immense continental expanses of Eurasia. As was to be expected, with the arrival of the "meridian exchanges", repetitive cold waves and snowfalls have been occurring for weeks on the Siberian central-eastern sector. The snowfalls and the consequent cooling of the layer of air close to the ground have now gone far south. To the region of Lake Baikal, northern Mongolia and in recent days even along the northern border of Kazakhstan, with snow showers that have whitened part of the north-eastern Kazakh steppe. In these hours, new snowfalls, up to the plain, are affecting central Siberia, up to low Asiatic Russia, along the border with Manchuria and the coasts of the Russian Far East, in front of the island of Sachalin. But snow showers also whitened the southern part of central Siberia, including the cities of Novosibirsk and Barnaul which received the first light dusting of white on the ground.

All the fault of the polar vortex that during the week decided to center its center of gravity right on the Siberian central-eastern sector, with a vast and deep cyclonic vortex, full of freezing air at high altitude, and with a minimum baric on the ground ready dropped below 982 hpa, which is translated from the Tajmyr peninsula to the high Siberian coast, which overlooks the Laptev sea, bringing widespread snowfall, sometimes even of moderate and strong intensity, accompanied by rather strong winds, generally from WNW and West , while currents from SW and S-SO affected the coast of eastern Siberia and the Republic of Jacuzia, the historic winter frost pole of the northern hemisphere. This deep depression, of Arctic origin, filled with very cold and heavy air masses of polar origin, during the week pushed a vast and complex frontal system in front of the high Siberian coast, followed by more humid and mild currents from western quadrants, rather sustained given the "horizontal baric gradient" that developed along the southern side of the polar cyclonic circulation. The latter, rather humid, flowing along the southernmost edge of the wide cold depressionary circulation attested with their minimum around the Siberian coast, collided with the much colder air masses of Arctic origin, descending from O- NO and NO, with sometimes intense winds, at over 50-60 km / h.

The interaction of the more humid and temperate western currents with the cold air, descending from the Arctic coasts, has determined the development of an irregular cloudiness that has brought widespread snowfalls that have affected large areas of the Jamal Peninsula, the Gyda Peninsula and that of Tajmyr, to extend, through the sustained and cold winds from O-NO and NO, to the plateau of central Siberia and Jacuzia, where there were even snow showers, discharged by cumulus clouds (cumulonimbus clouds in the air cold) which developed within the flow of very cold air, descending directly from the Arctic Ocean. The snow has whitened, over 11 cm thick, the famous village of Ojmjakon, in the heart of the Republic of Jacuzia, considered the main pole of the cold in the northern hemisphere during the winter months. In the night between Thursday 16 and Friday 17 October, after the first modest snow cover, the "Albedo" effect and the thermal inversion layer that developed during the night, favored by the ventilation almost absent in the low layers and by the serenity of the Heaven, Ojmjakon sank under the -25.1 ° C wall, for the first time since the beginning of the autumn season.

Note the marked extension of the snowpack (fresh snow) over most of the Siberian sector, with a considerable extension of the areas subject to the "Albedo" effect (credit NOAA)

This is one of the most significant minimum archives on the Siberian area since the beginning of the "skin cooling". The considerable extension of the snow on the vast moors of central-eastern Siberia is speeding up the process of "skin cooling" which at this time of the year begins to churn out the first colds on the northern hemisphere, in view of the entry into the scene of the winter season. The areas subject to the "Albedo" effect, thanks to the early snow of October, now extend to Altai, north of Mongolia, and north of Kazakhstan, where the first snowfall has already arrived. During late autumn and winter the vast plains, plateaus and immense steppes between Siberia, Kazakhstan, Mongolia and the other former Soviet republics of Central Asia, north of the Caspian Sea, are affected by a strong cooling of the layer of air close to the ground. This consistent cooling, better known also as "skin cooling", is caused by a series of factors, including the persistence of dry air, the substantial reduction of sunlight during the day and the remoteness of the mitigating action of seas or oceans , in addition to the strong radiation that characterizes these places during the long winter nights. In some areas of central-eastern Siberia, between December and January, even -50 ° C -60 ° C can normally be reached, as in the Republic of Jacuzia. This creates a layer of freezing and very heavy air, close to the ground, with a thickness limited to 1000-2000 meters, which gives rise to the famous "Russo-Siberian" thermal anticyclone, that is, a vast high pressure zone of purely origin cold, structured only in the lower layers.