Why do some typhoons come from the sea, but rainfall comes from fresh water?

Precipitation mainly comes from water vapor, not sea water blown by typhoons!!! Typhoons come from the tropical ocean, where the temperature is high and sea water evaporates more. After the typhoon forms, it moves towards the mainland, carrying water vapor with it. It collides with air masses over the continent to form precipitation.

The standard for dividing fresh water and salt water is based on their salinity. Salt water is 35‰, and fresh water is only 0.01-0.5‰. The original water on the earth came from a large number of comets carrying water ice. After impacting the earth, the water ice After melting, it was distributed in impact craters, and the water flowed downwards to form the most primitive ocean on earth.

Water circulates in nature. Surface water evaporates to form precipitation. This water is all fresh water. Precipitation gathers into rivers. Rivers are mostly fresh water. There are only some closed lakes where evaporation is greater than the sink all year round. The flow gradually turns into a saltwater lake, and the rivers merge into the ocean. When the rivers flow to the ocean, trace amounts of minerals on the surface are dissolved in the water, and finally flow to the ocean. After billions of years of evaporation, the ocean's mineral content continues to concentrate, making the salt water degree gradually increases.

When water evaporates, the minerals in the water will not evaporate in one piece, but will continue to be concentrated in the remaining water. Therefore, water vapor is fresh water, but when it condenses in the air, it needs to be condensed in the air. Dust acts as condensation nuclei, so precipitation is not pure water, but fresh water with very low salinity.

The heavy rainfall caused by typhoons mainly comes from water vapor. Only in coastal areas, due to strong winds and strong waves, some water spray can indeed be picked up by the typhoon, which will press a large amount of sea water to the coast, and the sea water will be wrapped up. It can form relatively localized salt water rainfall. This kind of rainfall is not normal, and the water droplets that are blown up cannot reach very high before falling.

As it moves toward the interior of the land, the salt water wrapped up by the typhoon is gone, leaving only light water such as water vapor. The density, dryness, and humidity of the air mass on the land surface are inconsistent with that of the typhoon air mass. , the lighter air mass will be lifted after the collision. During the lifting process, the water vapor in the air mass condenses into small water droplets. When the lifting force of the wind on the water droplets is less than the gravity of the water droplets, rainfall will form, so the water vapor located inside the land Precipitation is all freshwater rain, and typhoons affect a large area. Once a typhoon makes landfall, it will cause widespread precipitation. The key to the problem is the formation process of precipitation. Precipitation mostly comes from water vapor rather than directly blown sea water.

In addition, rainfall in the interior of the land can also be caused by water vapor formed by the transpiration of rivers, lakes, seas, and forest and wetland plants. Such precipitation is generally relatively limited in scope, while surface evaporation in inland areas is It is small, and ocean water vapor cannot reach it, so it is relatively dry with less rain and many saltwater lakes.