Question

Why are the oceans main source of moisture in the air

Answer 1

Humidity is not the same everywhere! It can change each day and is generally different in locations that have different climates. On the interior of continents, where the air is further from oceans and less able to pick up vapor from the sea surface, there is generally lower humidity than places that are near the ocean. Also, because warm air can hold more moisture than cool air, locations with warm climates, such as those near the equator, generally have higher humidity than locations with cooler climates, such as those near the poles.