1. THE WATER CYCLE
The Water Cycle

2. Nature is always moving water through the air, land, and plants…
What is the Water Cycle?
The water cycle
Nature is always moving water through the air, land, and plants…
so that the water we use is constantly recycled

3. Evaporation: The process of turning from a liquid to a gas or vapor.
The Water cycle
Evaporation: The process of turning from a liquid to a gas or vapor.
With the energy from the sun, water rises with the air high up into the troposphere
During this process impurities and salts in the water are left behind

4. transpiration The water cycle
During the process of photosynthesis, plant lose water vapor to the atmosphere
This process of evaporation through plant leaves is called transpiration
In large forests, an enormous amount of water will transpire through leaves

5. Humidity and Relative humidity
The amount of water vapor in the air is called the humidity.
When the air has the maximum amount of water vapor it can hold it is said to be saturated.
The amount of water it takes to reach saturation is dependent on temperature therefore it is more productive to talk about Relative humidity.
Relative Humidity: The amount of water in the air compared to the maximum it can hold. (expressed as a percentage)

6. condensation The water cycle
The air temperatures decrease as the water vapor rises into the troposphere
Water droplets form to create clouds when the air reaches a specific temperature called the Dew Point
This process of going from a vapor to a liquid is called condensation

7. Water falls from the clouds as rain, snow, sleet, or hail
Precipitation
The water cycle
Water falls from the clouds as rain, snow, sleet, or hail

8. Runoff
The water cycle
Some water stays on the earth’s surface and flows into rivers, lakes, reservoirs, etc.
Then the cycle begins again, as water from the earth’s surface evaporates into the atmosphere

9. Infiltration
Some water on the surface will enter the soil through infiltration and eventually reach groundwater.
Different surfaces have different infiltration rates

10. About 75 percent of the earth’s surface is covered by water
Why is it important to preserve water?
The water cycle
About 75 percent of the earth’s surface is covered by water
But only 0.01 percent of this is available for living organisms to use
The rest is “locked up” as salt water or is frozen in polar ice caps and glaciers