Earth holds a fixed amount of water.
Ninety-seven percent of this water is salty ocean water.
Only three percent of Earth's water is fresh water.
Only one percent of this fresh water is accessible on the surface.
Step one begins when the sun heats the ocean surface.
Liquid water absorbs this heat and transforms into invisible gas.
Eighty percent of all water vapor comes from our oceans.
This warm gas rises high into the sky.
Step two is transpiration, where plants release water vapor.
First, roots pull liquid water up from the soil.
Then, leaves release this water through tiny pores.
One single oak tree releases forty thousand gallons of vapor every year.
Step three is condensation, where rising vapor cools down.
The temperature drops three point five degrees Fahrenheit for every thousand feet.
This cold air forces the rising vapor to clump together.
The vapor turns into liquid droplets to form clouds.
Step four is precipitation, when clouds get too heavy with water.
Gravity pulls this stored water back down to the ground.
Above thirty-two degrees Fahrenheit, water falls as liquid rain.
Below thirty-two degrees Fahrenheit, water freezes into snow.
Step five is collection, which divides water into two main paths.
Path one is runoff, where water slides into rivers.
Path two is infiltration, where water sinks deep into the soil.
Both paths eventually empty back into the ocean.
Let us review the five steps of the water cycle.
First, water evaporates from oceans and transpires from plants.
Second, the rising vapor cools and condenses into clouds.
Third, precipitation falls and collection returns it to the sea.
This same water has recycled for four billion years.