Ocean Layers Lab-The interaction of salinity, temperature, & density

Density is: ______

Salinity is: ______

Use the information you learned yesterday about salinity and the information in the paragraph below to answer the pre-lab questions.

Temperature and salinity affect the density of water. Salinity does not differ much through the ocean waters, therefore oceanographers need to be accurate when measuring salinity. Today, in this lab you are going to predict how temperature affects density. Oceanographers know that ocean water has formed layers according to density. Low-density water exists near the surface, and higher-density water occurs below. There are three main layers of the ocean: shallow surface mixed zone, transition zone, and deep zone. The surface zone is mixed because the waves, tides, and currents come together. The zone extends from sea level to about 300 meters below. It only accounts 2% of ocean water. The transition zone occurs below the surface zone, but above the deep zone. This zone accounts for about 18% of ocean water. The deep zone is that lowest layer, resting right above the ocean floor. Water density is very high in this zone and it contains 80% of ocean water.

Diagram of layers:

Pre-Lab Questions:

  1. How does salinity affect density? ______
  2. How does temperature affect density?

______

______

  1. Where do you think the coldest water is located in the ocean? ______
  2. Which is the most dense layer of the ocean?______
  3. Which is the least dense layer of the ocean?______
  4. Which layer of the ocean contains the most salt?______

SALINITY AND DENSITY DEMO

  1. In which beaker does the golf ball sink? ______In which did it float? ______
  2. What was different about the two beakers? ______
  3. What conclusion can you make about the effect of salinity on the density of water? ______

*Temperature & Density Video Clip

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. 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. 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.
  1. Describe the pycnocline.
  1. 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.

  1. What are ocean currents?
  1. What factor drives surface ocean currents? What is a gyre?