1. The Water Cycle

2. The water on Earth is limited
It goes through a cycle that changes its form and location, but no new water is created. We drink the same water the dinosaurs did!

3. The cycle
There are 5 parts to the water cycle, and we can start the cycle at any point, then follow the cycle through.
Can you name the 5 parts?

4. The 5 parts of the water cycle are:
Evaporation/Transpiration
Condensation
Precipitation
Accumulation

5. What powers the Water Cycle?
The Sun
How?
The Sun transfers its heat energy to the
water on Earth, which causes evaporation.
What is evaporation?
A change of a liquid to a gas—when water evaporates from the Earth’s surface, it enters our atmosphere.

6. ALSO…
Another form of transferring water to the atmosphere is called transpiration.
This is similar to evaporation, but it comes from plants and trees.
Think of it like a plant that is sweating, and the plant “sweat” (water) evaporates.

7. Transpiration
Transpiration is the transfer of water vapor from plants to the atmosphere

8. I said the Sun transfers it’s Heat Energy to the water, what is meant by heat energy?
Heat is a form of energy which causes molecules to move faster and spread out.
There are three main ways to transfer heat…can you name any?

9. Heat Transfer The three methods of heat transfer are Radiation
Conduction
Convection

10. Radiation
This can best be described as the warm feeling you get from the Sun, or by sitting next to a fire.
The heat is radiating out, and you feel it’s energy warming you.

11. Conduction This is the actual transfer of heat through contact.
Some examples would be
Touching a hot plate
Walking barefoot on the sand at the beach and burning your feet
Can you think of one?

12. Convection Convection is the transfer of heat by the flow of material.
Examples of convection heat transfer are
Using a blow-dryer
Heating a bowl of soup

13. So now we know the Sun powers the water cycle…what is next?
Well, after evaporation and transpiration we have condensation, followed by precipitation, and accumulation, then the cycle continues.

14. Sun’s Heat Energy

15. Condensation
Condensation is when water vapor (or gas) changes back to a liquid.
This happens when the water vapor in our atmosphere cools enough to form droplets.
This is how clouds form. We will discuss this more in-depth later.

16. After condensation, we have precipitation; can you figure out what precipitation is?
CORRECT!!!
As the water droplets combine and get bigger and bigger they fall back to Earth and accumulate to complete the cycle.
Precipitation can be in one of four forms; can you name them?

17. Atmospheric Conditions
The type of precipitation we have depends on the atmospheric conditions in a particular place.
To understand this, we must first understand our Atmosphere; we will talk about this soon.

18. After precipitation is Accumulation
This is simply the water coming back to Earth’s surface and accumulating in the form of ice caps, rivers, lakes and oceans.

19. To recap the water cycle
There are 4 main parts to the water cycle, but remember there is no particular order.
Let’s name and describe each one.
Evaporation/Transpiration, Condensation, Precipitation, and Accumulation.

20. Earth's Atmosphere

21. Earth’s Atmosphere Divided into 5 main layers Troposphere
Stratosphere (contains Ozone Layer)
Mesosphere
Thermosphere
Exosphere

22. 500km
80km
50km
Ozone Layer
(Ozone Layer is within the stratosphere)
12km

23. Troposphere
Lowest layer of the atmosphere —we live here. Extends about 12km high
Contains 75% of the atmospheric gas—Our atmospheric gas is mostly Nitrogen (78%) and Oxygen (21%).
Contains 99% of water vapor
Clouds, rain, and snow form here.

24. Stratosphere Layer above troposphere—between 12km and 50km high.
Ozone layer exists here. Protects Earth from Sun’s harmful rays also referred to as Ultraviolet radiation.
An Ozone molecule is 3 oxygen atoms.

25. Mesosphere Layer above stratosphere—between 50km and 80km high.
This is the “middle” layer of the atmosphere.
Meteors are seen in this layer

26. Thermosphere Layer above mesosphere—between 80km and 500km high.
Thickest layer of atmosphere.
Named for it’s high temperatures.
The Space Shuttle orbits the Earth here.
Auroras form in this layer

27. Exosphere
Outer most layer of the atmosphere—starts at 500km and eventually becomes Outer space.
Most satellites are in this section.

28. Temperature changes with height in atmosphere

29. Temperature changes
Troposphere—decreases with height because air is thinner and absorbs less heat.
Stratosphere—increases with height because ozone layer traps most of Suns energy.
Mesosphere—decreases with height because very few molecules to trap heat (similar to our troposphere)

30. Temperature changes cont.
Thermosphere and Exosphere—increases with height because it absorbs high amounts of Sun’s radiation (closest to Sun).

31. Any questions?? Now that we know about our atmosphere,
We will concentrate more on the layer that we live in… we call this the
Troposphere

32. Water cycle and our troposphere
Does the temperature increase or decrease with height in our troposphere?
So, when dealing with water, where would you expect to see frozen water, up high or down low?
What are some names for frozen water?
Ice
snow

33. If temperature decreases with height
Why isn’t all precipitation hail, sleet, or snow?
Let’s discuss this…understand the question, think, then raise your hand to answer.