A large amount of water vapor contained in the ocean air comes from the evaporation of seawater.
Seawater is mainly water (that is, fresh water), and there are other salts, about 90% of which are salts containing potassium, iodine, sodium, bromine and other elements such as sodium chloride, magnesium chloride, magnesium sulfate and magnesium carbonate.
In the process of seawater evaporation, because the salt in seawater is difficult to evaporate under natural conditions, it precipitates in seawater and water can be directly evaporated into the air. So the water vapor contained in the sea surface atmosphere is fresh water. Typhoon and sea breeze bring the water evaporated from seawater into the atmosphere to high altitude to form precipitation, which is also fresh water, not seawater.