Experiment - Currents

Transcription

1 CURRENTS Curriculum Outcome: Describe the interactions of the ocean currents, winds, and regional climates. Curriculum Outcome: Carry out procedures in order to investigate how temperature differences in water cause currents Curriculum Outcome: & State a conclusion based on experimental data about the formation of water currents

2 Experiment - Currents Get a large beaker of room temperature water Put a little bag of ice at the edge of the beaker Place a drop of food colouring near the bag of ice What happens? Use a thermometer to test the temperature of the water in different places. Draw a conclusion from the experiment.

3 Observation Checklist for Assessment Observation: Rarely Always Carries out procedures carefully Uses instruments effectively Organizes, compiles and displays data

4 What is a current? A current is water moving in a certain direction. What causes currents? Currents are caused by cooler water sinking and pushing warmer water upward

5 What are convection currents? Circular currents caused by the difference in temperatures from the bottom to the top of the water. They help redistribute nutrients and oxygen in lakes that are icecovered in the winter.

6 What is an overturn? An overturn is mixing the upper and lower levels of water. Overturns occur in the spring and fall, when convection currents mix the surface and bottom waters.

7 Ocean Currents Convection currents exist in the ocean on a global scale. Cold water at the poles sinks and tends to flow toward the equator. The warmer, equatorial water is pushed upwards and warmed even more. It flows along the surface of the oceans to replace the water moving away from the poles. These surface currents are helped by winds. As the water moves from the equator it cools and begins to sink. This completes the cycle.

8 What Factors Affect Ocean Currents? Remember that Earth is not a ball standing still. It rotates and spins and is affected by the gravitational force of the Sun and the Moon. Also, strong winds blow around the Earth and the continents get in the way. This all affects the flow of ocean waters. However, ocean currents do form consistent circular patters called gyres.

9 What are gyres? Ocean currents moving in large circles in the Northern and Southern Hemispheres.

10 What is an ocean basin? An ocean basin is the floor of the deep ocean

11 Why do gyres flow in giant circular patterns instead of straight lines? The position of the continents. The shape of the ocean basins. The rotation of the Earth causes gyres to move in a circular pattern.

12 Describe the differences and similarities Similarities Both are moving water Both are types of currents Both affect climate Both are restricted to and named for a specific location Both affect the moving of nutrients and oxygen in the water between gyres and currents Differences Gyres are larger than currents and are made up of several currents Gyres are circular in nature/ Currents are more linear or semi-circular Gyres circle half an ocean/ Currents flow in a smaller part of the ocean

13 Understanding Concepts Explain the significance of convection currents to the survival of many aquatic organisms. In both lakes and oceans, convection currents stir up and redirect nutrients and dissolved oxygen throughout the water body. This adds to the survival of aquatic organisms.

14 Where are some important fishing areas in the oceans? The major fishing grounds around the world are mainly found on the continental shelf around each continent, particularly on shallow banks.

15 What causes these areas to generate such large numbers of fish? The best fishing grounds are usually where two currents meet, causing the water to gush and become unstable. Nutrients are brought to the surface of the water, promoting growth of aquatic plants and algae. Any food chain with a good supply of producers (plants) also has large numbers of animals, so plenty of fish would feed in these areas.

16 Explore What do the terms El Nino and La Nina mean? Explain them. Explain the effects that temperature, salinity, pollution, overfishing and upwelling have on oceans and lakes.

17 Ocean Currents 1HYFg Wind video 2RRk