The Water Cycle

The Water Cycle

What is the water cycle? 

the continuous movement of water within the Earth and it's atmosphere. It is a complex system that includes liquid water evaporating into water vapor, condensating to form clouds, and precipitating back to Earth in the form of rain and snow.

Everywhere!!

Notice how only 2.5% of all Earth's water is freshwater, which is what life needs to survive. Over 96% of all water is found in the oceans! Almost all of it is locked up in ice and in the ground. Only 1.3% of all freshwater is surface water, such as lakes and rivers. Surface freshwater is only 1.3% of all freshwater. Most of surface freshwater is locked up in ice, and another 20% is in lakes. Water covers 70% of the Earth's surface!!

Definitions 

atmosphere -  layers of gases surrounding a planet or other celestial body. Earth's atmosphere is composed of about 78% nitrogen, 21% oxygen, and  1% other gases.

water - is a chemical compound consisting of two hydrogen atoms (H) and one oxygen (O)  atom (H2O).

sun - a star at the center of the solar system. It is a hot ball of gases that gives off great amounts of energy 

run off - water "running off" the land surface

Define water.

1. Snow and Ice
2. Two hydrogen atoms and one oxygen atom
3. A gas in our atmosphere
4. H2Q

Define atmosphere.

1. H2O
2. layers of gases surrounding the planet
3. Air
4. The sky

More Definitions

evaporation - the process of turning from liquid into vapor.

condensation - the process where water vapor becomes liquid. Condensation happens one of two ways: Either the air is cooled to its dew point or it becomes so saturated with water vapor that it cannot hold any more water.

Infiltration - the movement of water into the ground from the surface. 

precipitation - is any liquid or frozen water that forms in the atmosphere and falls back to the Earth. It comes in many forms such as; rain, sleet, and snow.

clouds - a visible mass of condensed water vapor floating in the atmosphere, typically high above the ground.

sublimation - is the conversion between the solid and the gaseous phases of matter, with no intermediate liquid stage.

transpiration - The release of water from plant leaves.

What is evaporation?

1. The process of liquid turning into a vapor
2. A visible mass of condensed water
3. The process where water vapor becomes liquid
4. Snow

What is the sun?

1. A star at the center of our solar system
2. A heat source for Earth
3. A ball of gas
4. All of the above

How does it start?

Step 1: Evaporation. Water absorbs heat energy from the sun and turns into vapor. Water bodies like the lakes, oceans, and rivers are the main source of evaporation. 

Step 2: Condensation. Water rises up into the Earth's atmosphere. At high altitudes in the sky, water becomes tiny ice/droplet particles because of the low temperature. 

Step 3: Sublimation. Ice directly converts into water vapors without converting into liquid water. Ice sheets of the North Pole and the South Pole and the ice caps on the mountains are the main sources of this. 

Step 4: The clouds (condensed water vapors) then pour down as precipitation due to wind or temperature change. This occurs because the water droplets combine to make bigger droplets. These water droplets fall down as rain. If the temperature is very low (below 0 degrees), then the water droplets would fall as snow. 

Step 5: As water precipitates, some of it is absorbed by the soil. The roots of the plants absorb the water and push it toward leaves where it is used for photosynthesis. The extra water is moved out of leaves through stomata (very tiny openings on leaves) as water vapor. 

Step 6: As the water pours down in whatever form, it leads to run off.As water runs over the ground it displaces the top soil with it and moves the minerals along with the stream. This runoff combines to form channels, rivers and ends up into lakes, seas and oceans. 

Step 7: Some of the water that precipitates does not runoff into the rivers and is absorbed by the plants or gets evaporated. It moves deep into the soil. The water seeps down and increases the level of ground water table. It is called pure water and is drinkable! 

Let's recap! 

Take a breath with the class after all that information. Summarize with the picture shown how the water cycle is processed. 

Any questions? 

Let's discuss! 

Give the students a chance to ask for any clarification they need on the information given.