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Ladoga lake




Ladoga lake
Area: 18 135 km2
The greatest depth: 230 m

Lake Ladoga - a lake in Karelia (northern and eastern coast) and Leningrad region (western, southern and south-eastern coast), the largest freshwater lake in Europe. Refers to the pool The Baltic Sea Atlantic Ocean. The area of ​​the lake without islands is from 17,6 thousand km2 (With the islands of 18,1 thousand kilometers2); Volume of water mass - 908 km3; Length from south to north is 219 km, the greatest width is 138 km. The depth varies unevenly: in the northern part it varies from 70 to 230 m, in the southern part - from 20 to 70 m. On the shores of Ladoga Lake there are the cities of Priozersk, Novaya Ladoga, Shlisselburg in the Leningrad region, Sortavala, Pitkyaranta, Lahdenpohja in Karelia. In the Ladoga Lake 35 rivers flow into the river, and only one originates - the Neva. In the southern half of the lake there are three large gulfs: Svirskaya, Volkhovskaya and Shlisselburgskaya lips.

Climate

The climate above Lake Ladoga is moderate, transitional from moderately continental to moderately-marine. This type of climate is explained by the geographical location and atmospheric circulation characteristic of the Leningrad region. This is due to the relatively small amount of solar heat entering the earth's surface and into the atmosphere. Due to the small amount of solar heat, moisture evaporates slowly. For a year there is an average of 62 sunny days. Therefore, during most of the year, days with cloudy, cloudy weather, scattered lighting prevail. The duration of the day varies from 5 hours 51 minutes in the winter solstice to 18 hours 50 minutes at the summer solstice. Over the lake there are so-called "white nights", advancing 25-26 May, when the sun falls over the horizon no more than 9 °, and the evening twilight almost merge with the morning. The white nights of 16-17 July are coming to an end. In total, the duration of the white nights is more than 50 days. Amplitude of the average monthly sums of direct solar radiation on a horizontal surface with a clear sky from 25 MJ / m2 In December to 686 MJ / m2 in June. Cloudiness decreases on average for a year the arrival of total solar radiation by 21%, and direct solar radiation - by 60%. Average annual total radiation 3156 MJ / m2. The number of hours of sunshine is 1628 per year.

Ladoga lake

The lake itself has a noticeable effect on climatic conditions. This is characterized by a smoothing of the extreme values ​​of climatic characteristics, as a result of which the continental air masses, passing over the surface of the lake, acquire the nature of marine air masses. The average air temperature in the area of ​​Lake Ladoga + 3,2 ° C. The average temperature of the coldest month (February) is 8,8 ° C, the warmest (July) + 16,3 ° C. The average annual rainfall is 475 mm. The smallest monthly precipitation falls in February - March (24 mm), the largest - in September (58 mm). During the year, in the greater part of Lake Ladoga, western and south-western winds predominate. The average monthly wind speed in the open part of the lake and on most islands from October to January-February 6-9 m / s, in the remaining months 4-7 m / s. On the coast, the average monthly wind speed varies from 3 to 5 m / s. Stitches are rare. In October, storm winds are often observed on Lake Ladoga at a speed of more than 20 m / s, the maximum wind speed reaches 34 m / s. Breezes are observed throughout the coast in summer on windless sunny days and clear nights. The lake breeze starts around 9 hours in the morning and continues until 20 hours of the evening, its speed is 2-6 m / s; It extends to 9-15 km deep into the land. Fogs are observed most often in spring, late summer and in autumn.

Ladoga lake
Shores, bottom relief and hydrography of the lake

The area of ​​the lake without islands is from 17,6 thousand km2 (With the islands 18,1 thousand km2); Length from south to north is 219 km, the greatest width is 138 km. The volume of water mass of the lake is 908 km3. This is 12 times more than annually poured into it by rivers and carried by the river Neva. Seasonal fluctuations in the water level in the lake are small due to the large area of ​​the water surface of this reservoir and because of the relatively small annual variation in the amount of water entering it. The latter is due to the presence of large lakes within the catchment area of ​​the Ladoga Lake and the presence of hydroschemes on all major tributaries, which together provides a fairly even flow of water throughout the year. The coastline of the lake is more than 1000 km. The northern shores, ranging from Priozersk in the west to Pitkyaranta in the east, are mostly high, rocky, heavily indented, form numerous peninsulas and narrow bays (fjords and skerries), as well as small islands separated by straits. The southern coasts are low, slightly indented, podzaplivaemye because of neotectonic submeridional skewing of the lake. The coast here is replete with shoals, rocky reefs and banks. In the southern half of the lake there are three large gulfs: Svirskaya, Volkhovskaya and Shlisselburgskaya lips. The eastern coast is scarce, two gulfs - Lunkulanlahti and Uksunlahti, fenced off from the side of the lake by one of the largest islands of Ladoga - Mantsinsaari. Here there are wide sandy beaches. The West Bank is even less rugged. He was overgrown with a dense mixed forest and shrubbery, approaching close to the water's rim, along which placers of boulders. Rocks of stones often escape from the capes far into the lake, forming dangerous submarine shoals.

Ladoga lake

The relief of the bottom of Lake Ladoga is characterized by an increase in depth from south to north. The depth varies unevenly: in the northern part it ranges from 70 to 230 m, in the southern part - from 20 to 70 m. The average depth of the lake is 50 m, the largest is 233 m (north of Valaam Island). The bottom of the northern part is uneven, worn by depressions, while the southern part is more calm and more smooth. Lake Ladoga occupies the eighth place among the deepest lakes in Russia. Transparency at the western shore of Lake Ladoga 2-2,5 m, at the eastern coast of 1-2 m, in the near-shore areas 0,3-0,9 m, and to the center of the lake increases to 4,5 m. The least transparency was observed in Volkhov Bay (0,5-1 m), and The largest - to the west of the Valaam Islands (in summer 8-9, in winter over 10 m). On the lake there are constant disturbances. During strong storms, water "boils" in it, and the waves are almost entirely covered with foam. The water regime is characterized by overtaking phenomena (fluctuations in the water level at 50-70 cm annually, maximal up to 3 m), seiches (up to 3-4 m), wave height in storms up to 6 m. The lake freezes in December (coastal part) - February (central part), is opened in April - May. The central part is covered with solid ice only in very severe winters. Because of the long and strong winter cooling, the water in the lake and in the summer is very cold; It heats up only in the thin upper layer and in the coastal strip. The temperature regime differs in the central deep-water part of the lake and on the coast. The surface water temperature in August is up to 24 ° C in the south, 18-20 ° C in the center, near the bottom near 4 ° C, in winter under ice 0-2 ° C. Fresh and clean water (except for areas contaminated with industrial wastewater), minerals and salts are dissolved in an insignificant amount. Water refers to the hydrocarbonate class (low content of calcium and magnesium salts, slightly more than nickel, aluminum).

Ladoga lake
Pool and Islands

In the Ladoga Lake flow 35 rivers. The largest river that flows into it is the Svir River, which carries water from it Lake Onega. Also, the lake receives water through the Vuoksa River from Lake Saimaa, and across the Volkhov River from Lake Ilmen. It also falls into the rivers Morye, Avloga, Burnaya, Kokkolonoki, Soskuyonyoki, Ijoki, Airajoki, Tohmajoki, Janisjoki, Syuskyuonoki, Uksunjoki, Tulemajoki, Minalanjoki, Vidlitsa, Tuloksa, Olonka, Obzhanka, Voronezh, Syas, Lava, Ryabinovka, Naziya and others. . Neva is the only river flowing from Lake Ladoga. The catchment area is 258 600 km2. Approximately 85% (3820 mm) of the incoming part of the water balance gives inflow of river water, 13% (610 mm) - atmospheric precipitation and 2% (90 mm) - groundwater inflow. About 92% (4170 mm) of the expenditure part of the balance goes to the Neva River, 8% (350 mm) - to evaporation from the water surface. The water level in the lake is not constant. Its oscillations are clearly visible over a lighter strip on the surface of rocks leaving into the water. On the Ladoga Lake about 660 islands (an area of ​​more than 1 ha) with a total area of ​​435 km2. Of these, about 500 is concentrated in the northern part of the lake, in the so-called skerry region, as well as in the Valaam (around 50 islands, including the Bayev Islands), the Western archipelago and the group of islands Mantsinsaari (about 40 islands). The largest islands are Riekkalansari (55,3 km2), Mantsinsaari (39,4 km)2), Kilpola (32,1 km)2), Tulolansari (30,3 km)2) And Valaam (27,8 km)2). The most famous on Lake Ladoga Valaam Islands - an archipelago of about 50 islands with an area of ​​about 36 km2, Due to the location on the main island of the archipelago of the Valaam Monastery. Also known is the island of Konevets, which also houses the monastery.

Ladoga lake
Flora and fauna

The northern and eastern coasts of the Ladoga Lake belong to the subzone of the middle taiga, and the southern and western to the subzone of the southern taiga. For the middle taiga are characteristic spruce forests, without undergrowth, with a closed stand and a continuous cover of brilliant green mosses. In the subzone of the southern taiga, dark coniferous species with an undergrowth dominate, where lime, maple, and elm sometimes occur, a grassy layer appears with the participation of oakgrass grasses, and the moss cover is less developed than in the middle taiga. The most characteristic type of forest is spruce forests. The islands of the lake are rocky, with high, up to 60-70 m, sometimes steep banks, covered with forest, sometimes almost naked or with sparse vegetation. The southern and southwestern coast of the lake has been overgrown with reeds and cattail for 150 km. Here there are havens and nesting places of waterfowl. On the islands there are a lot of nesting gulls, blueberries and cranberries grow on them, and on larger ones there are mushrooms. In Ladoga Lake there are 120 species of higher aquatic plants. Along the coasts of the islands and the mainland stretches a strip of reed thickets with a width of 5-10 m. A variety of macrophyte groups develop in deeply embedded bays in the land. The width of the overgrowth strip in these places reaches 70-100 meters. Almost completely there is no water vegetation along the eastern and western shores of the lake. In the open waters of the lake, vegetation is poorly developed. This is hampered by greater depth, low water temperature, a small amount of dissolved nutrient salts, coarse-grained bottom sediments, and frequent and violent disturbances. Therefore, the most diverse vegetation occurs in the northern - skerry - the area of ​​Ladoga. In the lake, 154 species of diatom, 126 species of green and 76 species of blue-green algae are common. In the deep Ladoga waters, only 60-70 thousand microorganisms per cm3, And in the surface layer - from 180 to 300 thousand, which indicates the weak ability of the lake to self-purification.

Ladoga lake

In Ladoga Lake, 378 species and varieties of planktonic animals were identified. More than half of the species are rotifers. The fourth part of the total number of species is composed of protozoa, while 23 percent falls together on the branching and copepods. Daphnia and cyclops are the most widespread zooplankton species in the lake. A large group of aquatic invertebrates lives at the bottom of the lake. In Ladoga they are found 385 species (mostly different crustaceans). The first place in the benthic fauna belongs to the larvae of insects, which account for more than half of all species of benthic animals - 202 species. Next come worms (66 species), water mites, or hydrocines, mollusks, crustaceans and others. The lake is rich in freshwater fish, which for spawning goes to rivers. There are 53 species and varieties of fish in the Ladoga lake: Ladoga slag, salmon, trout, paly, whitefish, ryadushka, smelt, bream, cheese, bluefish, gulber, raspberries, asp, catfish, pikeperch, roach, perch, pike, burbot and others. . The human impact on the reservoir reduces the number of valuable fish - salmon, trout, palia, lake-river whitefish and others, and the Atlantic sturgeon and Volkhov whitefish are listed in the Red Book of Russia. The most productive areas include the shallow southern part of the lake with depths up to 15-20 m, where the main fish fishery is concentrated, and the northern skerry region is the least productive. From the Gulf of Finland along the Neva for spawning in Volkhov and other rivers through the lake there is a sturgeon. Along the southern and south-eastern shore of Ladoga Lake pike perch is found. The salmon dwell in the lake, which in autumn goes to the rivers where it spawns. In Lake Ladoga and Volkhov, they breed Siberian hornets, Siberian sturgeon and other fish. In Lake Ladoga, 256 species of birds belonging to the 17 squads are regularly found. On the transit span in spring and autumn, there are more than 50 bird species. The migration links of Lake Ladoga range from Iceland to India and from southern Africa to Novaya Zemlya. The most attractive for birds is the southern Ladoga area. Here, on a flight there are grebes, swans, geese, ducks, waders, gulls, terns, cranes and cowherds, as well as nesting of river ducks, tufted blacks, red-headed ducks, gulls, terns, large and middle curlews, a large godwit, herbalist, golden plover And other waders, a gray crane, white-tailed eagle, an osprey, a kobchik, an owl, a bearded owl, a swamp owl and several other birds. The northern skerries are a nesting place for the greyhound grebe, large and middle sized crabs, gulls (including sea gull and creek), terns (including polar terns), waders and many other species; on the fly are observed accumulations of arctic ducks and waders. In Lake Ladoga, the only representative of the pinnipeds, the Ladoga ringed seal, lives. The number of seals in the lake is estimated at 4000-5000 goals (according to 2000 data). The species is listed in the Red Book.

Ladoga lake



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