Science Starter What is density? What are convection currents? What effect does density have on convection currents?

Today’s Agenda Warm Up & Objective Oceanography Notes Ocean Currents! Partner Share Class Discussion Exit Ticket & Homework

Objective 2.3.1: We will be able to explain how the density of ocean water is affected by temperature

Imagine you went to Myrtle Beach and found a message in a bottle from Madagascar 200 years ago. How do you think it got there? Why do you think it took so long?

#5.11 Aim: What are some aspects of the ocean? Agenda QOD (10) Lesson: oceanography(15) Activity: Ocean currents! (15) Share (5) Summary share (5) HW #12 Ocean water Does not just contain water! Ocean water has ~3.5% dissolved minerals which we call “Salt”

Three Important Factors in Oceans: Salinity: is the total amount of solid material dissolved in water (how salty the water is) Density: how heavy something is for its size (mass per unit volume) Temperature: influenced by the sun’s radiation and the depth of the ocean water

Ocean Density Variations: Salinity: increases with ocean depth Temperature: decreases with ocean depth Density: increases with ocean depth As the depth of the ocean water increases, the temperature DECREASES and the density INCREASES

Drastic Changes in Temperature and Density: Thermocline: layer of ocean between 300-1000 meters where there is a rapid change in TEMPERATURE with depth Pycnocline: layer of ocean between 300-1000 meters where there is a rapid change in DENSITY with depth

Three Ocean Layers: Surface Zone: 2% of ocean water is found in the surface zone Lowest density, lowest salinity and highest water temperatures Transition Zone: 18% of ocean water is found in the transition zone The layer is in between the warmer surface zone and the colder deep zone The thermocline and pycnocline are located in the transition zone

Three Ocean Layers: Deep Zone: 80% of ocean water found in the deep zone Sunlight never reaches the deep zone Water temperature is only a few degrees above freezing Highest density, highest salinity, lowest temperatures

Ocean structure Colder, saltier water is more dense and sinks #5.11 Aim: What are some aspects of the ocean? Agenda QOD (10) Lesson: oceanography(15) Activity: Ocean currents! (15) Share (5) Summary share (5) HW #12 Ocean structure Colder, saltier water is more dense and sinks - Surface water temperature changes much more than deep water

#5.11 Aim: What are some aspects of the ocean? Agenda QOD (10) Lesson: oceanography(15) Activity: Ocean currents! (15) Share (5) Summary share (5) HW #12 Horizontal movement Density differences, sunlight, and wind cause currents Ocean currents play a major role in maintaining Earth’s heat balance: Heat is transferred from the tropics (near the equator) where there is excess heat, to the polar region where there is less heat

#5.11 Aim: What are some aspects of the ocean? Agenda QOD (10) Lesson: oceanography(15) Activity: Ocean currents! (15) Share (5) Summary share (5) HW #12 Vertical movement Downwelling – water rich in dissolved gases sinks (brings O2 to deep-water life!) Upwelling – water rich in nutrients from the bottom rises (excellent for fisheries!)

Ocean Density Demo Density = Salinity =

SALINITY AND DENSITY DEMO In which beaker does the golf ball sink? In which did it float? What was different about the two beakers? What conclusion can you make about the effect of salinity on the density of water?

Discussion Questions How does salinity affect density? Where do you think the coldest water is located in the ocean? Which is the most dense layer of the ocean? Which is the least dense layer of the ocean? Which layer of the ocean contains the most salt?

PREDICT! 1. How does temperature affect density? 2. Why don’t the ocean layers mix together (include salinity and density in this answer) 3. List the ocean layers in order of least dense to most dense: ______________________, ________________________, ________________________________. 4. Now read pages 426-427 of your Earth Science book and explain HOW and WHY ocean layers formed: (3-4 complete sentences)

In oceans near the Equator, the Sun heats the water at the surface In oceans near the Equator, the Sun heats the water at the surface. As you travel deeper into the water, the temperature quickly begins to drop because of lack of sunlight. This rapid drop in temperature as you go deeper is called the thermocline. Once you get past the thermocline, about 1000 meters into the water, the temperature is only a few degrees above freezing!

As the temperature gets colder, the water gets more and more dense As the temperature gets colder, the water gets more and more dense. Remember, hot stuff rises because it’s less dense and cold stuff sinks because it’s more dense. Just like there’s a rapid drop in temperature as you go deeper into the ocean, there’s also a rapid rise in density. This rapid rise is called the pycnocline. Therefore, the less dense, warmer water will be at the surface of the ocean and the more dense, colder water will be at the bottom of the ocean. 1. Describe the thermocline. 2. Describe the pycnocline.  3. What are the characteristics of the water you would find at the surface of the ocean? At the bottom?

Ocean currents are the large-scale water movements that happen at the surface and depths of the oceans. Surface currents are driven by global wind patterns, while currents below the surface are driven by differences in water density. The major surface currents are called gyres—huge circles of water current that are pushed along by the wind. When wind moves the warm, less dense water along the surface, the colder, more dense water rises to take its place. This process is called upwelling.   4. What are ocean currents?  5. What factor drives surface ocean currents? What is a gyre?

https://www.youtube.com/watch?v=AasKk3HRyOI #5.11 Aim: What are some aspects of the ocean? Agenda QOD (10) Lesson: oceanography(15) Activity: Ocean currents! (15) Share (5) Summary share (5) HW #12 https://www.youtube.com/watch?v=AasKk3HRyOI

Exit Ticket 1. Which of the following affects the density of ocean water? salinity and salt content temperature and ocean animals salinity and ocean floor depth salinity and temperature 2. Which is the shallowest zone that only makes up 2% of all ocean water? the surface zone the transition zone the deep zone the mixed transition zone

3. Where would you find the lowest density seawater? surface mixed zone deep zone transition zone abyssal zone 4. Why does ocean water form in layers? low-density water exists near the surface, and higher density water occurs below temperatures vary at each depth of the ocean salinity is increased in the surface zone and decreased in the deep zone salinity varies in different regions of the world