The biosphere of the planet is presented as an organized shell of the earth's crust. Its boundaries are mainly determined by the field of existence of life. The shell material has a heterogeneous physical and chemical composition. Living, biogenic, inert, bio-inert, radioactive matter, matter of cosmic nature, scattered atoms - this is what the biosphere consists of. The main difference of this shell is its high organization.
The global water cycle is driven by the energy of the sun. Its rays hit the earth's surface, transferring their energy to H2O, heating it, and turning it into steam. Theoretically, given the average rate of evaporation per hour, in a thousand years the entire oceans could be in the form of steam.
Natural mechanisms form large volumes of atmospheric fluid, carry them over fairly long distances and return them to the planet in the form of precipitation. Precipitation that falls on the Earth ends up in rivers. They flow into the oceans.
Distinguish between small and large water cycle. Small due to precipitation in the oceans. A large water cycle is associated with precipitation on land.
Every year about one hundred thousand cubic meters of moisture spills onto the earth. Due to it, lakes, rivers, seas are replenished,moisture also penetrates into the rocks. A certain proportion of these waters evaporates, some returns to the oceans and seas. Some are used by living organisms and plants for growth and nutrition.
The water cycle contributes to the moistening of artificial and natural ecosystems on land. The closer the area is to the ocean, the more precipitation falls. From land, moisture is constantly returned to the ocean. A certain amount evaporates, especially in forested areas. Part of the moisture is collected in the rivers.
The water cycle requires a significant amount of energy. About a third of the total amount received from the Sun is spent on the entire process. Before the development of civilization, the water cycle was balanced: as much water entered the ocean as it evaporated. With an unchanged climate, there would be no shallowing of rivers and lakes.
With the development of civilization, the water cycle began to be disturbed. Irrigation of agricultural crops contributed to an increase in evaporation. In the southern regions, there was a significant shallowing of the rivers. So, over the past thirty years, the Amu Darya and Syr Darya have brought very little water to the Aral Sea, as a result, the water level in it has also decreased significantly. At the same time, the appearance of an oil film on the surface of the World Ocean reduced evaporation.
All these factors have a negative impact on the state of the biosphere. It's not just the southern regions that are suffering. Serious changes are noted in the northern regions. More often recently, droughts have occurred, pockets of ecologicaldisasters. So, for example, in Western Europe, during the last three or four years, the weather has been very hot in the summer. Although in the past the climate in these areas was very mild. As a result of too much increase in temperature, forest fires often began to break out.
