The Baikal winds
The climate of Lake Baikal and its coast has features of sea climate and is considerably different from the climate of the surrounding area. The lake water masses get warmed in summer to the depth of 200-250 m and accumulate much heat. The winter at the lake is milder and the summer is cooler than in the rest of Siberian territory.
The main feature of the Baikal weather is its changeableness, contrast born by the whole complex of orographic, hydrological, atmospheric and landscape qualities of the basin. The lake is situated near the centre of the Asian continent with its characteristic severe continental climate.
In the warm half-year the quantity of precipitation decreases (to 200 mm on Bolshoi Ushkany island and to 160-170 mm in the southern part of Olkhon island). The biggest quantity of precipitation in the warm season is on the windward slopes of the eastern and south-eastern coast mountains facing the Baikal (about 1,200 mm). In the cold half-year, the process of cold air intrusion from the land into the lake cavity emerges over the Baikal which is warmer than the land, the wind activity grows.
One of the climate indices is the duration of sunshine. It is longer at Lake Baikal than in the nearest territories and even in the health resorts of the European part of the country. (In the north of the Baikal cavity the sun shines 1,900-2,200 hours a year, at the Baltic coast near Riga – 1,830 hours a year, at the health resort of Abastuman in the Caucasus – 1,994 hours a year).
The average year air temperature in the southern part of the cavity is 0.7°C, in the middle part it is -1.6°C, in the northern part it is –3.6°C. In Peschanaya bay at the western coast of Lake Baikal the average year air temperature is 0.4°C above zero. It is the warmest place in the whole Eastern Siberia. The temperature transition over 0°C is recorded in autumn in the late October-early November, in spring it is late February-early March.
The air temperature above the lake is influenced by the temperature of the underlying water surface and follows its isotherms curves. Throughout the year the average air temperature over the surface of Baikal changes from -21°C in winter to +15°C in summer in the open part of the lake and from -25°C to +17°C in the coastal parts. The water temperature of the coastal parts of the lake is influenced by warm waters of the big rivers, such as the Selenga, the Barguzin, the Upper Angara and others, because of that the summer water temperature in the delta parts of the rivers and gulfs, the Barguzinsky, the Chivyrkuisky, the Mukhor, the Proval, the Posolsky sor and others, reaches +22°C.
Air humidity over Lake Baikal depends on the temperature of the lake surface and the humidity of the coming air masses. The maximum evaporation is in November-December.
The cloudiness over Lake Baikal is less in summer, and in late autumn and even in winter before freezing-over it is greater than over the surrounding territory. It is the biggest at the north-eastern coast where in November and December there are up to 75% of cloudy days. The cloudiness at the western coasts is the least which is caused by fan effect during the air masses flowing over the coastal mountain ranges into the lake cavity. The maximum cloudiness is in November, the minimum one is in February. In October-December the lower cloudiness is intensive over the Baikal owing to moisture evaporation from its ice-free surface.
The thermal conditions of the Baikal water masses are formed under the influence of the radiation flows, turbulent thermal and moisture circulation of the lake and atmosphere and other processes.
The ice condition plays a great role in the life of the lake. Lake Baikal freezes every year, it is covered with ice gradually, from the north to the south, unlike other big lakes (Ladoga Lake, Onega Lake, Teletskoye Lake). The lake is frozen for almost 5 months a year. In late October shallow bays freeze, in the middle of winter (January 1-14) – the deepest parts. Freezing-over terms are different, the variations are about 40 days. The ice is about 1 m thick in winter (2-2.5 m on other lakes). In winter, when the temperature goes down, the ice compresses at night and tears into separate fields by thermal fields (backbone, main crack). When it is warmer the ice is expanded, pressures emerge on the cracks, the ice is crushed and backbone (main) hummocks are formed. In many parts of Lake Baikal local melting of ice beneath is recorded and ice-holes are formed (from several metres up to hundreds of metres in diameter). Ice breaking open starts on April 25-30 near Bolshoi Kadilny cape which is caused by ice melting under the influence of warm deep waters brought to the surface by the current and plentiful gas formation. The northern part of the lake is the last to be cleaned of ice (June 9-14).
The Baikal is one of the roughest lakes of the world. The lake surface is very seldom calm. The roughest place is in the strait of Olkhonskiye vorota, at the entrance into the Chivyrkuisky gulf (the waves can be 4 m high), as well as in shallow places, opposite the mouth of the Selenga river, at the entrance into the Barguzin gulf and near the northern coast of Bolshoi Ushkany island (the waves are 6 m high and 22° steep).
In warm season winds directed from the land to the lake dominate, in cold season – winds blow mostly from the lake to the land which is peculiar for sea coasts.
Heavy gales at Lake Baikal are common in late summer and in autumn. The Baikal is free of ice at that time, and flows of chilled air from the coastal slopes speed to it along the valleys. The maximum wind speed at the lake is recorded in April, May and November. The minimum one is in February and July. 80% of summer gales are in August-September, the waves in the middle cavity of the lake are up to 4-4.5 m high.
The diversity of stable Baikal winds is reflected in their local names (more than 30).
Verkhovik, or the upper wind (the Angara)
Verkhovik, or the upper wind (the Angara) is the northern wind blowing from the valley of the Upper Angara river along the lake from the north to the south. The first long blowing verkhoviks are common at the lake in the middle of August. Sometimes such a wind blows for 10 days in succession. By verkhovik the weather is usually sunny, it blows tranquilly without sharp rushes, there are almost no waves at the coast, but in the open part of the lake the water is darker and the lake is covered with white foam. In late November-early December the verkhovik shakes the Baikal with heavy steep waves up to 4-6 m high. The signs of verkhovik’s intensification are glowing bright red horizon before sunrise and a cloudy “cap” over the capes of Baklany and Tolsty.
Barguzin blows mostly in the central part of the lake from the Barguzin valley across and along the Baikal. The wind is even with the power gradually growing. It is considerably shorter blowing than verkhovik. Barguzin brings sunny stable weather.
Kultuk is the wind blowing from the southern end of the Baikal along the whole lake. Kultuk brings gales and rainy weather with it. The wind is not so long blowing as verkhovik. Kultuk is more common and stronger in autumn. Its peculiarity is fog appearing on the bare rocks of the Khamar-Daban mountain range.
Gornaya is western and north-western lateral wind falling suddenly from the mountains. It is the most insidious gusty wind. It starts suddenly and becomes stronger very quickly. The heralds of the wind are torn cumulus clouds flowing over the mountains of the western coast. The wind prevails from October till November.
Sarma is a variety of gornaya, the strongest and the most horrible wind at the Baikal. It blows from the valley of the Sarma river flowing into the Maloye sea. Its speed is more than 40 m per sec. The wind becomes strongest within an hour. In summer the wind can start suddenly and end in the same way. In autumn sarma can be a day and night long. The wind originates because of the peculiar Sarma valley narrowing to the mouth which forms a kind of wind tunnel at the exit, among vertical rocks. The heralds of sarma’s appearance are clouds over the Trekhglavy (Three-headed) bare rocks of the Pribaikalsky mountain range. Pieces tear off the clouds and crawl down, they dissolve at once over the lake and form broad stripes of ripples on the water.
Fogs at Lake Baikal are common in July. They originate because of the condensation of moisture brought onto the cold mirror of the lake by the warmed air. The fogs of the cold half-year are of evaporation type. They can be observed in calm weather. They last 5-6 hours mainly in the morning, seldom over 2 days. The fogs are often extremely thick. At the height of 100-150 m over the surface of the lake the fogs are transformed into thick cloudiness which becomes cumulus clouds at a bigger height. The clouds are sometimes carried to the east beyond the Baikal cavity, they are recorded as an atmospheric phenomenon because cumulus clouds are not formed over the continent in winter.
There are most fogs in the southern cavity of the Baikal, at the Khamar-Daban coast. There are least fogs over the Maloye Sea, in the Peschanaya bay (7 days a year) and near the villages of Kultuk and Oimur (5 and 4 days a year).
Mirages are observed near the north-eastern part of the island of Olkhon, near the cape of Solnechny and near the island of Bolshoi Ushkany. There are usualy 2-6 days with mirages. Sometimes their number reaches 16 a year.