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TEXT 6 THE USE OF SOLAR ENERGYThe sun possesses a limitless amount of energy and mankind is looking for different ways to utilize it because time will come when we shall not have any other energy but the Sun’s, coal, oil and gas will be used up. The most primitive device for using the heat of the sun is the gardener's greenhouse. Usually this device consists of the solar water-heater placed on the roof of the greenhouse and covered with glass. The water circulating in it is heated by the sun, and then pumped into a hot-water tank warming the greenhouse. Such a 100 square-meter greenhouse was not long ago built in Turkmenia. It will use solar energy to grow flowers and vegetables all the year round on a commercial basis. Solar energy is used both for heating houses and for cooling them. For example in Florida many «Solar houses» have been built. In these houses some material is used to take in and to keep heat of the sun and to give it away gradually as required. Water is a good material for the purpose, but Glauber’s salt is even more efficient. It melts at a temperature of 90° taking in a large amount of heat which it gives back when it turns into crystal again. Another interesting material is gravel in the walls of the house, which it keeps warm on sunless days. In Ashkhabad there are many houses cooled with the help of solar energy. Ten children's institutions in the same city have been equipped with showers. They look like any other showers, except that water for them is heated by the sun to a temperature of 60° on the south sides of the houses. As Turkmenia gets more than 180 sunny days each year (as many as Egypt and California) solar showers can be used from early spring till late autumn. A solar plant to distil underground water has been operating for several years in the Central Kara-Kum Desert. Its initial capacity was three cubic meters of water daily. After the evaporator the area had been increased to one hectare, the capacity went up four-fold. This is enough to provide water for a large number of sheep. A group of scientists from Turkmenian Academy of Sciences has made experiments on solar energy concentrators and gathered enough data on possible potential performance of solar electric stations generating cheap electricity in the Kara-Kum Desert. As the result a solar furnace developing temperatures of 3000° (in a sunray focal point) has been built. Electricity generated by this furnace costs a half of that generated by thermal stations. In the near future Kara-Kum will become a large producer of cheap electricity. The amount of solar energy per square meter here is equivalent to the energy got from burning 200 kg of the best coal. The most efficient way of generating electricity from sunlight, however, seems to be the «solar battery». The first solar batteries were semi-conductor crystals of germanium or silicon similar to those used in transistors. When the sun lights such a crystal, an electric current is generated. Since their first demonstration in 1954 the solar battery has been extensively developed and used in one of the greatest achievements of mankind – in space research on boards of space ships, space rockets and sputniks. Solar batteries are very good for the purpose because of their long life. TEXT 7 WATER There is no life without water. Man can live without clothes, without shelter, and even for time without food. Without water he soon dies. All his food contains water from about 60 percent in meat to 95 percent in watery fruit. His body is about 70 percent water. The air surrounding him contains enormous quantities of water in the form of vapour. The surface of the earth is 70 per cent water, to an average depth of over 4 kilometres. And yet man often does not have enough water. Water led man forward. The need to carry and keep it gave rise to pottery. Water, in fact, was at the roots of civilization – people settled down on the banks of great rivers. Industry is thirsty, too. We need 10 litres of water to produce one litre of petrol, 100 litres to produce one kilogram of paper, 600 litres to produce one kilogram of woolen cloth, 3500 litres to produce one ton of dry cement and In Africa, where surface water is scarce and ground water unobtainable, women spend most of their time carrying water from springs and rivers which are sometimes as much as 15 kilometres or three hours walk away. Under such conditions the amount of water used is nothing but absolute minimum. The earth has as much water as it ever had. What can man do to provide enough water for life? There are new methods of treating raw water, filtration and chlorination. There are modern methods of collecting, pumping, storing and distributing water. There are gigantic projects of taming the rivers, of harnessing their strength to produce power for man’s use, preventing floods and using the water for increasing the harvest of the land and providing food for growing population of the world. Perhaps a practical way will be found of making the rain fall where it is most needed. A clean, plentiful and convenient water supply in all parts of the world must be provided. TEXT 8 FRESH WATER RESOURCES The Earth’s water cycle or hydrologic cycle is the continuous circulation of moisture and water on our planet. The time required for a water particle to pass through one or more phases of the hydrologic cycle varies from a few hours to months or even centuries. A water particle may be evaporated from the ocean and in a short period fall back as rain or snow on the same water surface. If a water particle falls as snow or hail on a mountain height, it may remain there for months until it is melted, and joined with other melted particles on the long journey overland or underground. If a water particle is evaporated from the ocean and carried into the polar regions, falling there as ice or snow, it may remain frozen for centuries before it returns to the ocean as part of an iceberg or as melted outflow from the glacier. Rain, hail, and snow are various forms of precipitation. Precipitation that falls upon land areas is the source of all our fresh water supply. We depend upon it to compensate the quantity that is taken from lakes, streams and wells for numerous uses. Hydrologists estimated that the natural water cycle is far more intensive than had been supposed. Annual evaporation from the Earth’s surface amounts to the colossal figure of over half a million cubic kilometres of water, while the atmospheric moisture is renewed every ten days on the average. River water has a 12-day replacement cycle. Glaciers proved to be slowest «accumulators of moisture». Their replacement cycle is 8500 years. These figures will make it possible to achieve a more accurate picture of the world’s fresh water resources. TEXT 9 FORESTS SAVE WATER When we cut down trees or plow under grass, the land is left with nothing on it to hold back the water. Every time it rains, the water flows over the land and is carried out to sea where we can’t use it. Such water carries soil and minerals with it. Often, the amount of water is so great that rivers flood. The water is wasted. We can conserve water by planting trees, grass or other types of vegetation to absorb or slow down the run-off of waters. Hillsides that are too steep to be farmed should be covered with forests. The «floor» of a forest is spongy and absorbs water from rain and snow. The soil of grasslands also stores water this way. A bare soil lets rain and melting snow run over its surface without soaking in. This may cause floods in rivers in the spring but in the summer the streams and rivers dry up because the bare soil did not store enough water. The water table drops very low in these areas. This means that springs will stop running and wells will dry up.   ЧТО ПРОИСХОДИТ, КОГДА МЫ ССОРИМСЯ Не понимая различий, существующих между мужчинами и женщинами, очень легко довести дело до ссоры...  Живите по правилу: МАЛО ЛИ ЧТО НА СВЕТЕ СУЩЕСТВУЕТ? Я неслучайно подчеркиваю, что место в голове ограничено, а информации вокруг много, и что ваше право...  ЧТО И КАК ПИСАЛИ О МОДЕ В ЖУРНАЛАХ НАЧАЛА XX ВЕКА Первый номер журнала «Аполлон» за 1909 г. начинался, по сути, с программного заявления редакции журнала...  Конфликты в семейной жизни. Как это изменить? Редкий брак и взаимоотношения существуют без конфликтов и напряженности. Через это проходят все... Не нашли то, что искали? Воспользуйтесь поиском гугл на сайте:
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