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§ 49. Glaciers (textbook)

§ 49. Glaciers


1. Remember how the temperature of height?

2. What is heavier than water: liquid or solid?


Formation glaciers. Some water hydrosphere of our planet is in solid state. Snow and ice covered large expanses of land. If all the ice roztaly, the ocean levels rose to a 64 m and would have flooded vast areas of land with thousands of settlements.

Glacier - A cluster of ice on land. Unlike the river ice, he not formed from water and from snow. Glaciers are formed where one year more snow falls than time to thaw. Such conditions are created only when negative winter and summer, ie in the polar regions and in the mountains above certain level. The limit above which snow does not have time during the year roztaty, called snow line. Height Snow line decreases from the equator to the poles, as in the same direction decreasing temperature. Thus, in the mountains at the equator (eg, Kilimanjaro) Snow line is at altitude of 4500 meters in the mountains of temperate latitudes (Alps) - At an altitude of 3000 m. In the polar latitudes,  constantly low temperatures, the snow line is at the bottom - in sea level. Above the snow line gradually compacted snow piled up and becomes ice.

Glaciers on the Earth is covered with 11% of the land. Ice cover reflects sunlight back into space. In such places there soil, No plants, rare animals and birds settle. Among the distinguished mountain glaciers and cover.


Fig. Mountain glaciers


Features mountain glaciers.Mountain glaciers formed on the tops of high mountains in all latitudes. They differ in shape and size. Glaciers form depends on the relief of the mountains: one of the top cover caps, others are on recess chashopodibni slopes, others filled mountain valleys. The largest mountain glaciers cover top Himalayas, Tien Shan and Pamir.

Under action of its enormous weight of ice can move - to flow. Their movement on Unlike the flow of the river, it is difficult to see. Because speed is very small Some- meters per day. Mountain glaciers descending down valleys in the form of long tongues that resemble icy river. They can take ice and tributaries have lodopady. This glacier, like a river, destroys, takes, laying rocks. On Devise surface it deep grooves and smooths performances. Road in Glacier vmerzayut fragments of rocks (clay, sand, stones) and, with it moving down. Having gone down below the snow line, the edge of the glacier melts. They piled brought him fragments of rocks. These glacial deposits are called Moreno. From under the edge of glacier flow streams that  feed the rivers. Longest mountain glacierDarwin length of 350 km located in the Andes in South America. "Champion" for the speed of is glacier Kvarayak, located on the island. Greenland. He slid into the ocean at speeds of 24 m per day.

Investing glaciers. Ice covering the surface cover- land regardless of its topography. They are formed in polar latitudes, snow line is very low. Glaciers, like panels covering mainland Antarctica, Greenland, Arctic Islands. They have the shape of domes, which power more than 3 km. Ice In this glacier is growing in the center of the dome and slowly spreads to the edges. Therefore, the entire glacier is moving to the edges.

Land glacier, descending into the ocean, vidlamuyutsya chunk. Sliding blocks in water and converted to - icebergs. The temperature of ice in the iceberg reaches -60 0C. Therefore, no large icebergs melt years. Some of them are of enormous size - tens of kilometers in length and width. Record large icebergs born off the coast of Antarctica. They can be long over 200 km, 80 km wide and 500 m thick over most part of the iceberg - 90% - is under water and it is not visible. As they go under the influence currents and winds, they become very dangerous for shipping. Many when a collision with an iceberg resulted in the death of ships and people.

Value glaciers. Glaciers can be compared with huge natural freezer, which is very vyholodzhuyut air. From glacier surface is constantly blowing winds. Therefore, ice shields at the poles determine the planet's weather and climate of the whole Earth.

Through circulation of water in mountain glaciers is delayed from 10 to 120 years and in Antarctica and Greenland - to 250 thousand years. So wet that fell out atmosphere in the solid state near the South Pole, is back in Ocean in a quarter of a million years. Because glaciers contain many (80%) "Preserved" the mostcleaner freshwater on the planet. Deliver it to the polar latitudes could icebergs. For example, one medium-sized iceberg contains as much fresh water how much per year it brings a small river. But so far there are only projects transporting icebergs to the shores of countries that are vulnerable to shortages Freshwater.


FAQ task

1. What is a glacier? How is it formed?

2. What features are detected formation of glaciers in the mountains?

3. Where the snow line will be higher - at 300 пн. sh. or 500 пн. sh.?

3. Where widespread ice cover?

4. What is called icebergs? How are they dangerous?

5. As glacier water participates in the global water cycle?

6. Possible formation of glaciers in the Crimean mountains or the Ukrainian Carpathians? What and they should change for this in nature?