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Salinity

Salinity. Goal: To compare characteristics of ocean water. Tonight’s homework: DR 2.1, 2.2 and 2.3 all due Fri . Warm-up: In your science journal:. 1) What is salinity? 2) What are the different minerals that make up the salinity of water? * HINT: Check out p. 40. The Dead Sea.

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Salinity

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  1. Salinity Goal: To compare characteristics of ocean water. Tonight’s homework: • DR 2.1, 2.2 and 2.3 all due Fri. Warm-up: In your science journal: • 1) What is salinity? • 2) What are the different minerals that make up the salinity of water? • *HINT: Check out p. 40

  2. The Dead Sea • Take 3 minutes to silently read through the article on the Dead Sea. As you read, think about the following questions: • What is unique about the Dead Sea? • What is the major problem in this area? • What is being proposed as a possible solution?

  3. The Dead Sea • Now, take 3 minutes to discuss your answers with the people at your table. • Unique? • Problem? • Solution? Now, write a short paragraph in your science journal to answer these three questions.

  4. Properties of Water H • Review the properties of water. • Discuss how we map the ocean floor. Goal: Tonight’s homework: • Study for map quiz tomorrow. Warm-up: Read p. 41. Then, in your journal: O H • What are the two main factors that determine the density of water? How does each factor influence its density? • (HINT  You might have to THINK about it!)

  5. Quiz Practice

  6. The Earth’s Oceans

  7. Division of the Global Ocean • Four main ocean basins 3. - the largest and has the greatest depth 4. – about half the size of the Pacific and not quite as deep 5. – third largest, largely in southern hemisphere 6. – about 7 percent the size of the Pacific, partly covered by ice Pacific Ocean Atlantic Ocean Indian Ocean Arctic Ocean

  8. Characteristics of Ocean Water • Salinity • Total amount of solid material dissolved in water • Typically expressed in parts-per-thousand (‰) • Average salinity is 35‰ ( = 3.5%) • Major constituent is sodium chloride (NaCl)

  9. Salinity 12) Which type of waters tend to be saltier (higher salinity)? In groups at your tables, discuss and come up with a reason for the answer you got for question 12 of your directed reading. Think about it: What factors could cause salinity to increase or decrease for a particular body of water?

  10. Salinity 13) What happens to salt water when it evaporates? Processes affecting seawater salinity • Decrease salinity (add freshwater) • Increase salinity (remove water) • Salt is left behind (salinity increases) • Precipitation • Runoff from land • Near the mouth of a river • Glacial melting • Evaporation (in hot, dry, sunnier areas)

  11. The Dead Sea

  12. Salinity Very low salinity where the river empties into the ocean. mouth of the Amazon River

  13. Where does the salt come from? 14) Sources of sea salts • Comes from _______________________ • Chemical weathering of rocks • Streams/rivers bring salts to ocean • Water evaporates from the ocean, leaving the salts behind • rivers and streams

  14. Temperature Zones • Surface zone • Warm, shallow, well-mixed due to currents • Thermocline • Thermo temperature • Cline  gradual change • Deep zone • Cold; Too deep for sunlight to penetrate • Cooler • Warmer

  15. Which Profile is Which? • summer • winter • Low latitude (tropical) • Mid-latitude (temperate) • High Latitude (polar) Which profile has the thickest thermocline layer? The thinnest? Which profile has the thickest surface layer? Thinnest? Which profile doesn’t have any distinct temperature layers?

  16. Review 4) If sunlight only reaches down 100 meters deep, why does the surface zone often go deeper (200 – 300 m)? Which of the three ocean layers (surface, thermocline, deep zone) holds the most water in the oceans? What actually is the thermocline? Thermocline

  17. Changes in Surface Temperature 19) Surface water temperature varies with the a. b. latitude time of year • Lower surface temperatures are found in high-latitude regions (away from the _____________ ) • Higher temperatures found in low-latitude regions equator

  18. Global Thermostat 25) What is the most important function of the oceans? Absorb heat from the sun * Regulate the Earth’s climate 26) Why are waters at the equator warmer than waters at higher latitudes? The equator receives much more direct radiation and heat from the sun.

  19. Away from the equator, the same amount of light radiation is spread over a much bigger area. By the way, why do we have seasons on Earth?

  20. What is this?

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