1. Water How much of the Earth’s surface is covered by water?
Three-fourths of the Earth’s surface is covered by water.
The total water supply of the world is 326 million cubic miles. A cubic mile of water equals more than one trillion gallons. 
About 3,100 cubic miles of water, mostly in the form of water vapor, is in the atmosphere at any one time. If it all fell as precipitation at once, the Earth would be covered with only about 1 inch of water. 

2. Drinkable water How much of Earth’s water is drinkable?
Most of the water on Earth, 97% to be exact, is salt water found in the oceans. Only about 3% is fresh for drinking and irrigation.
Only about 3% of Earth's water is fresh. Two percent of the Earth's water (about 66% of all fresh water) is in solid form, found in ice caps and glaciers. Because it is frozen and so far away, the fresh water in ice caps is not available for use by people or plants. That leaves about 1% of all the Earth's water in a form useable to humans and land animals. This fresh water is found in lakes, rivers, streams, ponds, and in the ground. (A small amount of water is found as vapor in the atmosphere.)  Over two-thirds of the earth's fresh water exists as ice in the form of glaciers and ice caps.

3. Water How old is the water you drank at this morning?
The water in your glass may have fallen from the sky as rain just last week, but the water itself has been around pretty much as long as the earth has!  
The water in your glass may have fallen from the sky as rain just last week, but the water itself has been around pretty much as long as the earth has!   When the first fish crawled out of the ocean onto the land, your glass of water was part of that ocean.  When the Brontosaurus walked through lakes feeding on  plants, your glass of water was part of those lakes.  When kings and princesses, knights and squires took a drink from their wells, your glass of water was part of those wells.

4. Water Properties
A water molecule consists of one atom of oxygen bound to two atoms of hydrogen.
The water molecule has a positive charge on the side of hydrogen atoms and a negative charge on the other side. Water molecules tend to attract each other because the positive ends attract to the negative ends.
When atoms react, they typically either require energy to make the reaction occur or give off energy to make the reaction occur. Now, you can take that water and freeze it to ice (solid), keep it as a liquid, or boil it to turn it into a gas (steam). To go between these phases, you either add or take away energy.
The water molecule, H2O , is a very polar molecule, somewhat like two little bar magnets glued together in a wide V shape. You know how bunches of magnets like to clump together. So water molecules attract each other strongly, and the substance water has higher melting and boiling points.
Water has a very simple atomic structure. This structure consists of two hydrogen atoms bonded to one oxygen atom (Figure 8a-1). The nature of the atomic structure of water causes its molecules to have unique electrochemical properties. The hydrogen side of the water molecule has a slight positive charge (see Figure 8a-1). On the other side of the molecule a negative charge exists. This molecular polarity causes water to be a powerful solvent and is responsible for its strong surface tension (for more information on these two properties see the discussion below).

5. States of Matter (phases)
Water can be found as a solid, liquid or gas.
Although water continuously changes states from solid to liquid to gas, the amount of water on Earth remains constant. There is as much water now as there was hundreds of millions of years ago. 
Water is unique in that it is the only natural substance that is found in all three states -- liquid, solid (ice), and gas (steam) -- at the temperatures normally found on Earth. Earth's water is constantly interacting, changing, and in movement.
Define matter as anything that takes up space and has mass. Mass is the amount of matter in something.
Activity 4: To try to inflate a balloon inside a bottle. 1.) Hold the top of the balloon and push the bottom of the balloon inside the bottle. 2.) Stretch the top of the balloon over the mouth of the bottle. 3.) Try to inflate the balloon by blowing into it. What happened? Why? (The bottle is filled with air. Blowing into the balloon causes the air particles (molecules) inside the bottle to move together, but only slightly. The air is in the way of the balloon, preventing it from inflating. Remember two pieces of matter cannot occupy the same space at the same time.) Try putting a hole in the bottom of the bottle and then see if the balloon can be inflated inside the bottle. Try different size bottles and holes.
Water's state is determined mostly by temperature.

6. Molecules
Small pieces of water are called molecules. Molecules are always moving.

7. Solid, liquid, gas
Liquid: The molecules are further apart and are not arranged in any special order. They are free to move in any direction, but are confined by their container.
Solid: The molecules are relatively close to one another, and the motion of each molecule is restricted by its interaction with other molecules.
Gas: The molecules are further apart and have little interaction with one another.

8. Density at Freezing
39°
32°

9. Freezing/Melting Freezing turns a liquid into a solid.
Melting turns a solid into a liquid.

10. Condensation and Evaporation
Condensation is a gas changing into a liquid.
Liquids evaporate into gases.

11. Sublimation and Frost Sublimation is a solid changing into a gas.
A gas becomes solid through deposition.
Sublimation - snow on a black top road or driveway, when the temperature is less than 0 C. Turns directly to vapor without making a puddle.

12. Water Cycle (Hydrologic Cycle)
Water is constantly being cycled between the atmosphere, the ocean and land. This cycling is a very important process that helps sustain life on Earth. 
Each part of the cycle drives the other parts.
Condensation
Water is constantly being cycled between the atmosphere, the ocean and land. This cycling is a very important process that helps sustain life on Earth.  As the water evaporates, vapors rise and condense into clouds. The clouds move over the land, and precipitation falls in the form of rain, ice or snow. The water fills streams and rivers, and eventually flows back into the oceans where evaporation starts the process anew. Learn a lot more about this complicated process in concepts.
Precipitation
Evaporation
Infiltration

13. Evaporation
Evaporation is the process where a liquid changes from its liquid state to a gaseous state.
For example, all of the water in a pot left on a table will eventually evaporate. It may take several weeks. But, if that same pot of water is put on a stove and brought to a boiling temperature, the water will evaporate more quickly.  Spray water on the back on student’s hand and ask them to wave it around: What happened to the water?
During the water cycle some of the water in the oceans and freshwater bodies, such as lakes and rivers, is warmed by the sun and evaporates. During the process of evaporation, impurities in the water are left behind. As a result, the water that goes into the atmosphere is cleaner than it was on Earth. 
Studies have shown that the oceans, seas, lakes, and rivers provide nearly 90 percent of the moisture in the atmosphere via evaporation, with the remaining 10 percent being contributed by plant transpiration.

14. Approximately 80% of all evaporation is from the oceans, with the remaining 20% coming from inland water and vegetation.
Winds transport the evaporated water around the globe, influencing the humidity of the air throughout the world. For example, a typical hot and humid summer day in the Midwestern United States is caused by winds blowing tropical oceanic air northward from the Gulf of Mexico.
Image by: Globe
Most evaporated water exists as a gas outside of clouds and evaporation is more intense in the presence of warmer temperatures. This is shown in the image above, where the strongest evaporation was occurring over the oceans and near the equator (indicated by shades of red and yellow).
Only about 10 percent of the water evaporated from the oceans is transported over land and falls as precipitation. Once evaporated, a water molecule spends about 10 days in the air.

15. Humidity
Most of the time, you can't see it, but the air contains a lot of water.  The amount of water in the air is called humidity. The atmosphere is the super-highway of the water cycle.
Here are some things to try for yourself to prove that water vapour is around you. Look at the air coming out of a friends mouth when he or she breathes. Can you see anything? Now breathe on a mirror that was in a refrigerator until it got cold. Do you see fog on the mirror? That fog is caused by tiny water droplets that formed when the water vapour in your breath was cooled by the cold mirror. If you live somewhere where winters are cold enough for ice to form outside, you have probably "seen your breath". A cloud forms outside your mouth when you exhale because the cold air cools the invisible water vapour in your breath and some of it turns into tiny water drops.
Puddles, wet clothes on a clothes line, blackboard washed with water
Just as oil floats on water because it is less dense, clouds float on air because the moist air in clouds is less dense than dry air.

16. Wind speed: the higher the wind speed, the more evaporation
Wind speed: the higher the wind speed, the more evaporation. Temperature: the higher the temperature, the more evaporation. Humidity: the lower the humidity, the more evaporation.
There is a number of climatic factors that affect evaporation. Most of them are quite obvious from our everyday experience. We know that after getting wet we will dry up faster if we stay in the sun, and it will be even faster on a windy day. When it is humid outside things do not seem to dry up as quick as when it is dry. So the evporation is higher when it is sunny, hot, windy and dry.

17. Transpiration
Transpiration is the loss of water from the leaves by evaporation; this helps keeps water moving round the plant by sucking water up from the roots.
10% of total evaporation

19. Condensation
Condensation is the opposite of evaporation. Condensation occurs when a gas is changed into a liquid.
Condensation occurs when the temperature of the vapor decreases.  When the water droplets formed from condensation are very small, they remain suspended in the atmosphere. These millions of droplets of suspended water form clouds in the sky or fog at ground level. Water condenses into droplets only when there are small dust particles present around which the droplet can form. 
Fog on glasses, car windows, ice water on hot day

20. Cloud Formation In the United States, there are 40
trillion gallons of water above your head on an average day.
Activity
Imagine a block of air, or air parcel, rising upward through the atmosphere. The air parcel expands as it rises and this expansion, or work, causes the temperature of the air parcel to decrease.
As the parcel rises, its humidity increases until it reaches 100%. When this occurs, cloud droplets begin forming as the excess water vapor condenses on the largest aerosol particles. Above this point the cloud droplets grow by condensation in the rising air.
If the cloud is sufficiently deep or long lived, precipitation will develop.

21. Cloud Formation
When the air cools, water vapor condenses into tiny water droplets, which form clouds.
What appears to be cloud-free air (virtually) always contains sub microscopic drops, but as evaporation exceeds condensation, the drops do not survive long after an initial chance clumping of molecules. As air is cooled, the evaporation rate decreases more rapidly than does the condensation rate with the result that there comes a temperature (the dew point temperature) where the evaporation is less than the condensation and a droplet can grow into a cloud drop. Evaporation increases with temperature, not because the holding capacity of the air changes, but because the more energetic molecules can evaporate more readily (with, of course, the caveat that evaporation is also influenced by things other than temperature, as described above).

22. Condensation Nuclei
The particles around which water vapor condenses are called condensation nuclei. Some condensation nuclei are smoke, dust, or salt crystals from the ocean.
Eventually, each condensation nucleus collects enough water to become a tiny droplet. The droplets are so small that they float in the air. A large number of the droplets forms a cloud.
These particles are called condensation nuclei and are so small that they can be seen only under an electron-microscope with a magnification of several thousand times.
Clouds also caused by lifting by fronts or mountains.

23. Three Main Ingredients
Moisture
Cooling air
Condensation Nuclei
Most of the condensed water in clouds does not fall as precipitation because their fall speed is not large enough to overcome updrafts which support the clouds. For precipitation to happen, first tiny water droplets must condense on even tinier dust, salt, or smoke particles, which act as a nucleus.

24. What stops a cloud from falling?
1 mile in diameter and 300 feet thick
Because unlike an elephant, a cloud's weight is spread out over a very large area. Plus, the cloud's droplets and crystals are very small--about one micron, or one-hundred-thousandth of an inch across. A cloud's individual particles are so small, in fact, that warm air rising from the earth's surface is able to keep them floating in the air. It's similar to how dust motes swirl in a shaft of sunlight. Although the bits of dust are affected by gravity, even the gentlest air currents are enough to keep them dancing around in the air
Clouds are composed primarily of small water droplets and, if it's cold enough, ice crystals. The vast majority of clouds you see contain droplets and/or crystals that are too small to have any appreciable fall velocity. So the particles continue to float with the surrounding air. For an analogy closer to the ground, think of tiny dust particles that, when viewed against a shaft of sunlight, appear to float in the air.
Have you ever observed (observing is different from just looking at something) a camp fire? As a log burns some of the carbon in a log is oxidized (that is it burns) and the combination of oxygen and carbon becomes carbon dioxide. Ash is what is left, material that was not oxidized.
As the fire burns, the air around it is heated and because the warm air is less dense than the cool air surrounding it, the warm air is forced to rise. The upward moving air (in meteorology we call it an updraft) carries some of the ash with it. Now think about it, ash from burning logs is not lighter than air, but it floats upward, pushed by the updraft.
Apply that same reasoning to a cloud. The liquid water drops and ice crystals are held aloft by rising air.

25. Stratus and Cumulus
The word stratus comes from the Latin word that means "to spread out." Stratus clouds are horizontal, layered clouds that stretch out across the sky like a blanket.
The word cumulus comes from the Latin word for a heap or a pile. Cumulus clouds are puffy in appearance. They look like large cotton balls.

26. Cirrus and Nimbus
The word cirrus comes from the Latin word for a tuft or curl of hair. Cirrus clouds are very wispy and feathery looking.
Nimbus means rain cloud.

27. Cumulus

28. Stratus

29. Cirrus

30. Cumulonimbus

31. CumulostratusStratus Clouds

33. Precipitation
When the temperature and atmospheric pressure are right, the small droplets of water in clouds form larger droplets and precipitation occurs.
precipitation-is water being released from clouds as rain, sleet, snow, or hail. Precipitation begins after water vapor, which has condensed in the atmosphere, becomes too heavy to remain in atmospheric air currents and falls.
Water is continually evaporating and condensing in the sky. If you look closely at a cloud you can see some parts disappearing (evaporating) while other parts are growing (condensation). Most of the condensed water in clouds does not fall as precipitation because their fall speed is not large enough to overcome updrafts which support the clouds. For precipitation to happen, first tiny water droplets must condense on even tinier dust, salt, or smoke particles, which act as a nucleus. Water droplets may grow as a result of additional condensation of water vapor when the particles collide. If enough collisions occur to produce a droplet with a fall velocity which exceeds the cloud updraft speed, then it will fall out of the cloud as precipitation. This is not a trivial task since millions of cloud droplets are required to produce a single raindrop.

34. Cloud Droplet – Rain Drop
Water is continually evaporating and condensing in the sky. If you look closely at a cloud you can see some parts disappearing (evaporating) while other parts are growing (condensation). Most of the condensed water in clouds does not fall as precipitation because their fall speed is not large enough to overcome updrafts which support the clouds. For precipitation to happen, first tiny water droplets must condense on even tinier dust, salt, or smoke particles, which act as a nucleus. Water droplets may grow as a result of additional condensation of water vapor when the particles collide. If enough collisions occur to produce a droplet with a fall velocity which exceeds the cloud updraft speed, then it will fall out of the cloud as precipitation. This is not a trivial task since millions of cloud droplets are required to produce a single raindrop.

35. Collisions and Coalescence
Raindrops can be produced by the collision and merging of cloud droplets. Collisions take place because the terminal velocity of a water drop increases as its size increases, over the normal size range of cloud droplets and raindrops. Large droplets fall faster then collide with and merge with smaller ones. When two rain droplets merge, "coalescence" has taken place. As a result of coalescence, the large drops can grow fairly rapidly.     Raindrops are also produced by the melting of ice crystals, snowflakes, and other frozen particles. When ice crystals exist in the presence of "supercooled" water droplets in subfreezing air, the crystals grow as the droplets evaporate. There is a pressure force driving the water molecules from the water to the ice, resulting in a rapid growth of ice crystals in the presence of liquid cloud droplets.     As ice crystals grow, the heavier ones fall. As a result, collisions and merging occur. A snowflake can be made up of a group of crystals stuck together. When such a particle falls through a layer of air whose temperature is above freezing, the crystals melt and raindrops are produced. In mountainous areas during the winter, valley locations often experience rain while snow falls at higher elevations.
Thick clouds – big raindrops
Thin clouds – small raindrops or drizzle

36. Precipitation
This is also the basic situation that leads to freezing rain. The difference being that, with freezing rain, the rain gets cold enough to freeze, but doesn't. This is a state called super cooled. When the super cooled rain strikes something it freezes almost instantly coating it with ice.
Sleet is frozen raindrops that bounce upon impact with a hard surface

37. Rain or Snow?

38. Hail

40. Runoff and Infiltration
Once the precipitation hits the ground:
It may become run-off
It may be soaked into the ground (infiltration)

41. Infiltration
Infiltration is an important process where rain water soaks into the ground. Water that infiltrates the ground becomes groundwater making up an aquifer.
When water returns to the Earth, it can be absorbed into the soil. This process is called percolation. Water will trickle through the tiny spaces between the soil particles and eventually collect above an impermeable rock layer. This water and saturated soil above the rock layer is called ground water.
Surface Runoff is the movement of water over land to points of lower elevations.  Water flowing across the land gathers in low points to form tiny rills, brooks, and tributaries that merge to form creeks and streams.  These elaborate systems of surfacewater all connect to larger streams and rivers and carry an extraordinary amount of water into lakes and oceans...
Precipitation may also get into plants, where it is evaporated through transpiration.

42. Infiltration
As the water infiltrates through the soil and rock layers, many of the impurities in the water are filtered out. This filtering process helps clean the water.

43. Infiltration

44. Slope

45. Vegetation 2 1 3
Vegetation reduces sediment by slowing runoff velocity and permitting greater infiltration.
Precipitation that collects on the leaves or stems of plants is known as interception.
Tree roots loosen and provide conduits through which water can enter the soil.
Vegetation protects the soil from pounding rainfall, which can close natural gaps between soil particles. 4 5

46. Aquifer
Aquifer is the term given to a rock unit that will yield water in usable quantities to wells or springs. Aquifers must be both
Porous
Permeable
Aquifer is the term given to a rock unit that will yield water in usable quantities to wells or springs. An aquifer can be visualized as a giant underground sponge which holds water and which, under certain conditions, will allow water to move through it. Depending on the type, the aquifer may contain both the saturated and unsaturated zones, or just the saturated zone.
Permeable material contains interconnected cracks or spaces that are both numerous enough and large enough to allow water to move freely.
Porous material contains spaces that can be filled by water.
Unconfined aquifers are bound by the water table; that is, they have no confining rock layers over the top of them
Some aquifers, however, lie beneath layers of impermeable materials. These are called confined aquifers, or sometimes artesian aquifers. A well in such an aquifer is called an artesian well. The water in these wells rises above the top of the aquifer because of confining pressure; the level to which it rises is called the static water level. If the water level rises above the ground surface, a flowing artesian well occurs.

47. Snake River Aquifer
The Eastern Snake River Plain Aquifer in Eastern Idaho is the largest aquifer in Idaho, and one of the largest and most productive aquifers in the world. The Eastern Snake River Plain covers more than 10,800 square miles of southeastern to south central Idaho. The plain stretches more than 170 miles from Ashton, south and west to Twin Falls and King Hill, and is more than 60 miles across at its greatest width. The elevation of the plain ranges from over 6,000 ft. to about 2,900 feet above sea level.
Snow and rain that falls on the 36,000 square-mile upper Snake River Basin, including parts of Wyoming, Utah, and Nevada, supply the Snake River and Eastern Snake River Plain Aquifer.
Each year, about 8 million acre feet of water flow past King Hill, the western boundary of the Eastern Snake River Plain. This is enough water to cover all of the Eastern Snake River Plain with about 16 inches of water.
In contrast, the entire Eastern Snake River Plain Aquifer is thought to contain as much as a billion acre feet of water, enough to cover the Plain with about 140 feet of water, creating a lake more than twice as deep as Lake Erie.

48. How Fast Does It Move?

49. Twin Falls Idaho Falls Less than 50 50-100 100-200 200-300
Craters of the Moon
Less than 50
50-100
More than 300

50. Surface Runoff
If precipitation occurs faster than it can get into the ground, it becomes runoff. Runoff remains on the surface and flows into streams, rivers, and eventually lakes or the ocean.
When water returns to the Earth, it can be absorbed into the soil. This process is called percolation. Water will trickle through the tiny spaces between the soil particles and eventually collect above an impermeable rock layer. This water and saturated soil above the rock layer is called ground water.
Excess lawn chemicals, pet wastes, oil and gas drippings along highways are all sources of pollution washing into the lakes, streams and recharge basins.
Runoff water reaches stream systems much faster than water which must percolate through the soil

51. Surface Water
Any water that travels or is stored on top of the ground. 

53. If you were a drop of water….
Reservoir
Approximate Residence Time
Glaciers
40 years
Seasonal Snow Cover
0.4 years
Soil Moisture
0.2 years
Groundwater: Shallow
200 years
Groundwater: Deep
10,000 years
Lakes
100 years
Rivers
0.04 years

54. Most Important Element

55. Words to Remember Evaporation Transpiration Condensation Precipitation
Surface Runoff
Infiltration
Aquifer

56. If you were a drop of water:
In a river (surface runoff)
To a lake
Groundwater
Animal
River
Clouds
Stay in lake
To groundwater (infiltration)
Lake
Stays in groundwater
To the ocean
Clouds
Stay in ocean
To an animal
Soil
Stay in animal
To clouds (evaporation)
Glacier
Lake
Ocean
Stay

57. In a one hundred year period, an average water molecule spends 98 years in the ocean, 20 months as ice, about two weeks in lakes and rivers, and less than a week in the atmosphere.
One inch of rain falling on one acre of land is equal to about 27,154 gallons of water. (United States Geological Survey)