Evaporation
Evaporation is the name of the process where liquid turns into gas. Particles in a liquid state are held together by little bonds, but high temperatures break these bonds and make the particles grow far apart from each other, turning the liquid into a gas.
When water evaporates, anything that was in the water remains behind. This includes salt, sugar, rocks, minerals and any other materials that sometimes end up in water.
Evaporation is a purifying process. It can clean water such as seawater which is too salty to drink. To do this the seawater has to be heated until it evaporates, leaving the salt behind. The steam then needs to be collected and cooled until it turns back into water. We are then left with pure water ready to drink.
Transpiration
Water can also make its way up to the sky thanks to the help of plants when they transpire.
This happens when plants absorb water from the soil with their roots and send the water to their leaves. A waxy layer known as the cuticle minimises water loss. On the underside of the leaves, the water is released through tiny pores called stomata. The water from the leaves eventually turns into gas through a process called transpiration. We cannot see this with our eyes but we can sometimes feel it. Areas with a lot of vegetation can have levels of humidity (or water) in the air; this water is coming from the plants. An oak tree can transpire around 151,000 litres of water a year!
The amount of water that can be transpired depends on the plant, the moisture of the ground, and the temperature and movement of the wind around the plants.
