Tien Shan is one of the highest mountain-mass in the ex-USSR. It is greatly visited by trekkers, backpackers, climbers and mountaineers. The CIS part of the mountain is situated in Kirgizia (the Respublik of Kirgizstan), the north and west ridges - in Kazakhstan, the southwest ridges of  Tien Shan - in Tadjikistan and Uzbekistan.
        Mountain-chains stretch from the West to the East for 1200 kilometers (in the ex-USSR). It's maximum width is 350-400 kilometers. In the north Tien Shan is limited by the Iliyskaya valley, in the south - by the Ferganskaya hollow, to the west - it joins the Alaysky ridge of the Gissaro-Alaysky mountain-chain.
        Ridges of Tien Shan are separated by intermountain hollows, which consist of continental sedimentary precipitation.
        Geologists refer Tien Shan to the old mountains, but it has high tectonic activity. We still remember the destroying earthquakes happened in Tashkent (the capital of Uzbekistan) in 1966. Seismologists say, that earthquakes have increased for the last years, there are 30-40 earthquakes every year.
        According to the orography structure, Tien Shan is generally divided into west, east, north, central and internal (the east part is situated in China). The internal part of Tien Shan includes the area of the Kayindy (Kayindy-Katta), Inylchek-Too (Inylchektau), Sari-Jazz, Tengritag ridges. The central part includes the Kuylu, Akshiyrak, Jetymbel, Nary-Too, Borkoldoy, Art-Bashi ridges and the rest part of the Terskey-Ala  Too (Terskey-Alatau) ridge.
        The north Tien Shan consists of the Kirgizkiy ridge, Kungey-Ala-Too (Kungey-Alatau), Ketmen, Chu-Iliysky mountains and Zailiysky Alatau which is situated to the north of the Issyk-Kul lake.
        The west Tien Shan includes the Talassky Alatau ridge with the Chatkalky, Chandalashsky (Sandalashsky), Pskemsky, Ugamsky, Fergansky, Atoyoksky ridges.
        The most ridges of Tien Shan have mountain glacier «alpine» relief. But side by side with keen summits and peaks there are many flat surfaces especially in the central and internal Tien Shan. Such surfaces, inclined to the south, crown the Terskey-Alatau (Terskey Ala Too) ridge.
        The bottom of the alpine valleys in the internal and central Tien Shan have flat surface as well. They are covered with grasses and considered to be good pastures. Tien Shan is a place of contrast, green meadow are in the vicinity of snowcapped mountains.
        At the slopes of the Tien Shan ridges it often happens soil erosion, scree and stone-fall. There is a high activity of mud flows in the north slops of Zailiysky Alatau. They often caused a damage to the capital of Kazakhstan - Alma-Ata (Almati). The catastrophic mud flow destroyed the Issyk lake in 1963. As a rule mud flow happens here every year, when snow is melding or when it is raining. Unfortunately it causes peoples death sometimes.
        The climate of Tien Shan is continental: hot summer in foothills and valleys, cool-in nival and subnival zones, severe winter, high fluctuation in temperature during a day and a year, little cloudiness and dry air. The sun is often shining here 2500-2700 hours per year (in Moscow, for example, 1600 hours). The variety of relief in Tien Shan, such as high ridges or deep hollows as well as cloudiness influence on the length of the sun shining. It is maximum cloudiness (7-8) in March-April, minimum (3-4)-in August-September.
        Air masses have a great influence on the weather. Heat belts in Tien Shan are changed from the foot of the mountains till summits.
        West air currents influence on the climate of the region. They carry moist air masses from Atlantic to the Tien Shan mountains. Mountain relief causes precipitation which reach 1600 mm per year in highlands, mainly in the slops facing the west and northwest. It is dry in the east slops and in the valleys of internal and central Tien Shan. Precipitation is about 200-300 mm per year. Maximum precipitation fall in the summer, but in the west slops-in the winter. Thickness of the snow cover in winter reaches 2-3 meters in the west valleys, as for the east slops and behind them, especially in the valleys of the internal and central Tien Shan snow is not falling. In spite of low temperature (-25°-28 °C) the valleys are used as winter pastures.
        The Issyk-Kul lake influences on the climate of the Issyk-Kul hollow. The water increases the air temperature by 10 °C, it is the very reason of the cool summer in Central Asia, the average temperature of July-August is about +16,5° +16,9 °C.
        The snow-line increases from the northwest to the sough-east as well.
        The Tallasky Alatau and the Kirgizsky ridge are covered with snow at the height of 3600-3800 meters in the north slops and 3800-4200 meters in the south ones. In the Central Tien Shan, in the Khan Tengri region, near the Pobeda ("The Victory")  peak snow is at the height of 4200-4450 meters. The central Tien Shan is not much covered with ice, because of its high altitude. The largest glaciers of  Tien Shan, such as South Inylchek (60 km), North Inylchek (about 35 km), Kaindy (25 km), Semenova (21 km), Mushketova (20 km) are situated here.
        The total area of Tien Shan is more than 7300 square km, the total number of glaciers reaches 7800. Glaciers of flat summits which cover ridges are typical for Terskey-Alatau.         Freezing is almost in permanent state, some glaciers are leaving, others are coming.
        At the time of a great ice-age Tien Shan was covered with more massive glaciers. They caused swells, moraines, glacial valleys and glacial lakes which are situated everywhere in Tien Shan.
        Ili, Chu, Tarym, Syrdarya rivers and their tributaries flow into reservoirs of the deserts of Middle and Central Asia or into the lakes of Tien Shan. Glaciers and snow feed rivers which have its sources in highlands. Therefore they have high water twice a year, the most powerful one is in summer (in July-August).
        The Naryn river draw particular attention for being one of the most powerful rivers in the ex-USSR. 700 glaciers feed Naryn. 630 rivers flow into it. Naryn descends from Tien Shan increasing its speed.
        There are many lakes in Tien Shan but the biggest and the most beautiful one is Issyk-Kul. It occupies the hollow between the Kungey-Alatau and Tereskey-Alatau ridges. Its maximum depth is 720 meters, average one is 278 meters, it's length is 1822 km, and it is about 58 km wide. Issyk-Kul takes the seventh place in the ex-USSR for its area, and the third place - for its width. The river doesn’t have flowing, therefore the water is salt.
        The following rivers of  Internal Tien Shan - Song-Kel, Chatyr-Kel are drying up nowadays. There are many lakes in highlands but they don’t have influence on climate.
        As it is mentioned above, there is a great variety of relief, climate, snow-line boundaries, fauna and flora in Tien Shan. 

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