It is the theory of kinetics. Solar energy heats up the superficial layer (surface) of water and the water molecules jump from the surface in to air (due to increased in energy). If the air is moving the molecule gets carried away and further heated to become a vapor. If still air is there, then only it will drop back to the surface.
This is the basis for perspiration also.
If you heat a solution, you are providing energy. Here, solar radiation is the source of energy. Besides, if the air is saturated with water vapors then the evaporation is less.
Remember, phase changes could not happen unless you change the temperature and of course, pressure.
Please note: Boiling is different from evaporation as applied to whole mass not for a layer of water.
Evaporation is the proccess of water turning into vapor.
vapor
The amount of water vapor in the atmosphere varies from place to place. Humidity is the term used to describe the amount of water vapor in the atmosphere.
Relative humidity the exact amount of water vapor in the atmosphere (specific humidity)
The Troposhere has the most water vapor then any other layer in the atmosphere.
The main processes that return water vapor to the atmosphere are evaporation and transpiration. Evaporation occurs when liquid water changes into water vapor from sources such as oceans, lakes, and rivers. Transpiration is the process through which plants release water vapor from their leaves into the atmosphere. Both of these processes contribute to the water cycle by replenishing the atmosphere with water vapor.
condensation
Condensation
Water vapor turning into water is a gas changing into a liquid. This process is known as condensation.
Nail polish remover is a volatile liquid (primarily acetone), which is neither a vapor nor a gas. Now, "volatile" means that it has a high vapor pressure, meaning that easily turns into a partial vapor at standard temperature and pressure (about room temp and a standard atmosphere). So, the acetone is mostly liquid, with some of it turning into vapor (gas) at any given time.
through evaporation
Water vapor