1. Lesson 4 Ocean Currents http://oceanexplorer. noaa
Lesson 4 Ocean Currents I. Ocean currents = Stream like movements of water
A. Surface currents= occur near or at the surface of the ocean
Can reach 100 m deep or deeper
Warm-water surface currents create warmer climates in coastal areas that would normally be cooler
Gulf Stream= warm water current is one of the strongest & moves more water than all of the rivers on Earth combined
Allows for a warmer climate around the British Isles

2. Cold-water currents: brings cooler water and milder temps
The California current brings cooler North Pacific water in and creates a much milder climate along the west coast

3. Stop and think
Where do most hurricanes hit the coast in North America?
If hurricanes are large tropical storms that originate over large bodies of warm water why does this make sense?
Should we watch for hurricanes along the California coast?

4. B. What Affects Surface Currents?
Continental Deflections: when surface currents meet continents, the currents “bounce” off or deflect off the land masses and change directions

5. https://youtu.be/i2mec3vgeaI
The Coriolis Effect= deflection of moving objects from a straight path due to Earth’s rotation
Earth is spherical & rotation is always 24 hours
Points on the equator travel faster than points closer to the poles
Causes currents and winds are deflected to the right in the Northern Hemisphere and to the left in the Southern Hemisphere
Noticeable in long unobstructed distances

6. Global Winds= winds that blow across the surface of the Earth’s oceans & push water across the Earth’s surface
Global Surface winds will match the pattern of the Global Surface Currents

7. C. What powers surface currents?= THE SUN
The sun heats the air at the equator more directly causing wind
Differences in heating causes pressure differences
Warm air is less dense than cool air so it rises
Rising warm air creates low pressure near the equator
Differences in pressure causes the wind and the wind causes the surface currents

8. II. Current Events A. How do deep currents form?
Deep currents= movement of ocean water far below the surface
Caused by differences in water density
Density= the amount of matter in a given space or volume
Density of ocean water is effected by salinity and temperature
Water with high salinity is denser than water with low salinity
Colder water molecules are closer together making it more dense than warmer water whose molecules are further apart
High density sinks and lower density water rises causing a current

9. B. What are convection currents?
Convection currents= movement of water that results from density differences
Can be vertical, circular or cyclical
Like a conveyor belt with surface currents on the top and deep water currents on the bottom
Water from the surface moves towards the poles, cools and sinks becoming the deep water current which pushes the the cold water towards the equator which warms becoming the surface
Currents carry the energy from the sun

10. Upwelling: Process in which cold, nutrient-rich water from the deep ocean rises to the surface to replace warm surface water
Winds “push” warm water away causing cold water to rise and replace the warm
Nutrients brought up are full of nitrates & iron that help plants grow in the photosynthetic waters
Phytoplankton & zooplankton are tiny plants and animals that depending on the upwelling

11. Current travel the World A. What do ocean currents transport?
Ocean currents transport ENERGY
Water absorbs large amounts of solar energy at the equator and through currents carries it to the poles
Influences Earth’s climate
Warm water releases energy in the form of eat as it cools

12. Ocean currents transport matter
Carries dissolved salt (NaCl)- sodium cholride
Carries dissolved gasses
Takes in CO2 through waves and releases O2= important controller of greenhouse gases

13. Lesson 5 Human Impact on Water A. Where is water
97% of Earth’s water is salt
3% is fresh
Of the 3% …
68-79% is in glaciers & icecaps
The remaining 30% is in groundwater and les than 1% is in fresh surface water surface

14. Water quality= measure of how clean or polluted water is
Water supply= the availability of water
Influences where people live and what they can grow
Water supply systems carry water from underground or surface water for usage by people

15. B. Threats to Fresh Water
Water Pollution= waste or other material is added to water so that it is harmful to organisms that use it
Point-source pollution= pollution that comes from a specific site
Can be controlled b/c you know where its coming from

16. Non-point source pollution= pollution that comes from many sources https://youtu.be/WfKmHl-45ls
More difficult to control because it doesn’t come from a single source
Hard to find the true source at times
Street gutters, fertilizers, draining from mines, salts from irrigation

17. C. Types of Water Pollution
Thermal pollution= any heating of natural water that results form human activity

18. Chemical pollution= harmful chemicals are added to the water supplies
Industry= chemicals used to process metals or oils
Agriculture= pesticides, herbicides, & fertilizer runs off into water sources
Acid rain= gases from burning fossil fuels mix with the water in the atmosphere

19. Biological pollution= live or dead organisms are added to the water
Microbes in animal or human wastes can cause disease
Eutrophication= an increase in the amount of nutrients in water
Artificial eutrophication= human activity increases the levels (wastewater & fertilizer runoff)

20. D. Measuring Water Quality
Dissolved oxygen= (DO) measure of the amount of dissolved oxygen gas that is in water
pH= a measure of how acidic or how alkaline the water is
Dissolved solids= measure of the amount of ions or microscopic suspended solids are in water
Turbidity= a measure of how cloudy the water is
Microbial load= identifying harmful microscopic organisms

21. E. Steps for Treating Water to Drink https://youtu.be/tuYB8nMFxQA
Screen out large debris
Add chemicals to make particles “stick” together
Flocculation= particles that are stuck together are heavy and fall out of suspension in the water
This will also remove bacteria & microbes that are in the particles that fall out of suspension
Chlorine is added to kill remaining microbes left in the water
Fluoride may be added to prevent tooth decay
Air is bubbled throughout the water before it is ready to drink
Potable= water suitable to drink
Oxygen removes certain harmful metals in water

22. F. Monitoring of Water quality
EPA Environmental Protection Agency: monitors, enforces, and sets standards for drinking water in public systems
Safe Drinking Water Act= federal law that ensures safe drinking water for people in the United States
Sets limits on the amounts of heavy metals, bacteria, or other things that could be in drinking water

23. G. Getting water into homes
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Surface water may be collected or wells may be dug into aquifers
Water is then piped into a water treatment plant where chemicals can be added, it is put into tanks for debris to settled, and then it can be pumped through pipes into homes
Growing populations have larger demands for water
Aquifers may subside (collapse) due to water being taken out of them too quickly before recharge is possible
Sinkholes may form
Near the coast if an aquifer is pumped out too quickly saltwater intrusion may occur
Salt water gets into the aquifer and contaminates the water

24. Death of a Sea= Aral Sea in South Asia0