1. Why do you think we need to keep it safe??
Our world is about 70% water!
Of that water:
97% is salty!
2% is stored in ice!
(glaciers / ice caps)
1% is in the ground, lakes, streams, rivers, and ponds.
So the water that is readily available for us to drink is very small!

2. Earth’s Oceans
Takes up about 70% of the Earth’s surface

3. Pacific Ocean
Atlantic Ocean
Indian Ocean
Arctic Ocean
Southern Ocean

4. Ocean Salinity Na = Sodium / Cl = Chlorine
NaCl = Sodium Chloride or SALT
Salinity – the amount of dissolved solids in a given amount of liquid

5. Ocean Salinity Some parts of the ocean are saltier than others
Coastal water in hot, dry climates has higher salinity
Coastal water in cool, humid climates has lower salinity
Reason? Warmer temperatures increase evaporation
Salinity near the coast is less than in the open ocean because fresh water from streams and rivers enters the ocean at the coast

7. Ocean Salinity
Water movement within the ocean can cause the salinity of different parts of the ocean to be higher or lower.
Slower moving water has higher salinity
Faster moving water has lower salinity

8. The Oceans and the Water Cycle
The water cycle is continuous
Moving from the ocean, to the atmosphere, to the land, and then back to the ocean!
The ocean is a BIG part of the water cycle because nearly all of Earth’s water is in the ocean!

9. The Water Cycle
Evaporation –Increased heat energy turns a liquid into a gas.
Condensation –Decreased heat energy turns a gas into a liquid.
Precipitation – when water falls back to the earth in the form of rain, sleet, snow, or hail.

10. The Water Cycle
Runoff- the movement of water to the oceans, mainly in the form of rivers, lakes, and streams.
Runoff consists of precipitation that doesn’t evaporate or is part of ground water.
All of Earth’s water eventually finds its way back to the ocean!!!

11. Freshwater vs. Saltwater
Who has ever been swimming in the ocean?
What differences to you notice about saltwater compared to swimming in a pool with freshwater?
Saltwater is denser than freshwater….so you float better in the ocean!
That’s what we call buoyancy!
Saltwater is more buoyant than freshwater!

12. Freshwater vs. Saltwater
Ever wonder why the oceans don’t freeze like lakes do?
Ever wonder why we use salt on ice in the roads to melt ice?
That’s because salt in water lowers the temperature at which the water will freeze!
Freshwater freezes at 32oF (0oC)
Saltwater freezes at about 28oF (-1.91oC)

13. REVIEW Which ocean is located between Africa and Australia?
What is the chemical formula for salt?
Where is the ocean’s salinity the highest?
What is condensation?
What are the 4 types of precipitation?