1. Sun-our star and the source of all energy on the Earth


2. Solar energy is the energy of the sun.


3. Radiation-how the SunÕs energy moves through space, as radiation strikes the EarthÕs surface it

changes into heat.


4. hydrologic or water cycle-endless process in which water evaporates from oceans and lakes, condenses into clouds and returns to the Earth as precipitation.

5. Solar energy heats the water and drives the water cycle

6. Three states of water-solid, liquid, and gas

7. three major steps of hydrologic cycle-evaporation/transpiration, condensation, and precipitation

8.  Energy is either added to or taken away during each step to cause the changes!

9. evaporation-water absorbs enough heat to change into a gas called water vapor.  Water vapor is INVISIBLE!!!  Molecules gain energy, energy is added.

10.  We CANNOT see water vapor!

11.  Oceans provide the greatest amount of water vapor.  ONLY the water evaporates, the salt stays behind in the ocean.

12. transpiration- plants losing water vapor to the air through leaves (plant sweat!)  Molecules gain energy, energy is added.

13. condensation- water vapor cooling down or losing enough energy to change into tiny droplets of water.  Molecules lose energy, energy is lost. 

14. clouds are caused by condensation.  Clouds are tiny droplets of water, they are NOT water vapor!

15. clouds form when water vapor condenses on dust, smoke or even salt particles from the ocean.

16. fog is a cloud that forms near the ground.

17. Dew is water droplets that have condensed on the ground in the cool morning air. 

18. frost-happens when water vapor condenses and freezes on grass, leaves, and other surfaces (windshields)

19. precipitation-liquid and solid forms of water falling from the sky to the ground. Molecules lose energy.

20. Precipitation forms when water droplets about the size of a period in a sentence start growing, must get about 100 times larger to fall.

21. When the water droplets get large enough, gravity pulls them towards the ground as precipitation.

22. 4 forms of precipitation- rain, sleet, snow, and hail.

23. Infiltration-a portion of the precipitation that reaches the Earth's surface seeps into the ground, adding to the aquifer.

24. runoff-water from precipitation making its way back into the ocean.

25. Accumulation-anywhere that water is stored during the water cycle; can be the oceans, lakes, rivers, or aquifers.  Water may be in an aquifer for a very short period of time or it can be there for thousands of years.