Science:Water Cycle

The water cycle is the continuous movement of water on Earth.
Heat energy from the Sun causes water on the earth to evaporate, forming water vapour.
Water cycle in Earth
1. Water evaporates from the ground and water bodies, living things also release water vapour into the air through respiration.
2.Warm air cools as it rises to the sky =>Water vapour in warm air condenses into tiny water droplets => gather to form clouds.
3.Water droplets become big and heavy =>fall as rain, snow or hail. Rain falls onto Earth as fresh water.
4. Back to step 1.( Cycle continues)

Clouds
Clouds provide us with rain, snow or hail = fresh water.
Clouds also help to reduce the effect of the Sun's direct rays on the Earth.
Clouds are made up of tiny water droplets, clouds in liquid state. 
Water droplets = visible
Water vapour = invisible
Snow
Snow = made up of snowflakes
Air temperature drops below freezing point(0 degrees) => water droplets in clouds freeze =>snowflakes are formed.
Hail
Hail = frozen rain or hailstones that fall from the sky, usually during summer thunderstorms.
Temperature near top of clouds is low. Water droplets freeze when they are there(near top of clouds) 
Air movements inside the clouds carry the frozen water droplets up and down a lot of times within the clouds. Each time they rise, another layer of ice forms around them. 
Frozen water droplets become too heavy to be carried by air movements => fall as hailstones 


Frost
Temperature of ground is below freezing point => air above ground becomes very cold =>water vapour (in the air) freezes into tiny crystals => crystals form a sparkling white coat of frost on the ground and trees.




The need for water in plants
Water plays an important role in carrying out life processes in plants.
Sufficient water for a seed would activate life processes within the seed and germination occurs
In the plant transport system, water helps in movement of substances within the plant.
Conditions for photosynthesis: Water, Light and Carbon dioxide