Water from the atmosphere
is a huge reservoir of moisture, and even in arid regions it contains, as a rule, more than 6-10 g of water per 1 m3, while in tropical regions this value reaches 25 g / m3. So, 1 km3 of the surface layer of the atmosphere in hot, arid and desert regions of the Earth contains up to 20,000 tons of water vapor. The amount of water at any given moment in the Earth's atmosphere is 14 thousand km3, while in all river channels there are only 1.2 thousand km3. Every year 577 thousand km3 evaporate from the surface of the land and ocean, the same amount then falls in the form of precipitation. The annual river runoff is only 7% of the total amount of precipitation. From a comparison of the total amount of evaporated moisture and the amount of water in the atmosphere, it is easy to see that it is renewed 45 times in the atmosphere during the year.