Ocean Currents Demo

This activity is taken from “Let’s Go Live with Maddie & Greg”, a live family science show on YouTube!

View the full episode this activity is taken from on YouTube

“We love this activity because it reminds us how important our oceans are!”

Materials you could use

A container of water

Bricks (or similar) to lift the container off a table

Plastic cups

Hot water

Blue ice cubes (It can help the experiment to add a little bit of salt to your ice cubes)

Red food colouring

Labels - equator, polar ice caps

Method

This activity is all about finding out how the ocean helps regulate the temperature of our planet, carrying hot and cold water around our oceans in a series of currents.

1. Set your tank of water on top of the bricks. You want the tank to have enough space below it so you can place your cups on the table beneath it. Get an adult to pour hot water into a few plastic cups.

2. Place the cups of hot water below the tank at one end and label this side of the tank 'The Equator'. The cups of water will start to heat the water in this part of your ‘ocean’, just like how the sun heats up the water at the equator.

3. Label the other side of your tank ‘polar ice-caps.’ Place your blue ice cubes into the water on this side of the tank.

4. Add a squeeze of red food colouring into the warming water on the equator side. Observe what happens to the blue cold water and the red warm water.

5. You could hold some white paper, card, or material behind the tank of water to help you to see what is happening. You should see the cold, blue water sink and moves across the bottom of the tank towards the 'equator'. The red water will rise and moves across the tank towards the 'polar ice caps'. This sets up a circular current.

The equator is an imaginary line around the center of the earth. It is hotter at the equator because it gets more direct sunlight.
Polar ice caps are found in the arctic (at the top or north of the planet) and the antarctic (at the bottom or south of the planet).

When the ocean demo is set up you should see that the cold blue water sink and moves across the bottom of the tank towards the warmer water. The red water will rise and moves across the tank towards the colder water. This sets up a circular current.

This happens because cold water is denser and sinks to the bottom of the tank. Hot water is less dense so it rises up. As the cold water sinks, it pulls water in above it, allowing the hot water to come across. As the hot water rises it pulls water in from below it.

We see this happening in our oceans - warm water flows away from the equator to the ice caps where it cools down. Coldwater at the ice caps sinks and flows towards the equator, where it gets warmed up and begins to rise and flow away again. This is known as thermohaline circulation.

Our favourite fact

In 1992, a cargo ship container tumbled into the North Pacific, dumping 28,000 rubber ducks and other bath toys into the ocean. Over the next 25 years, the ducks washed up on several different continents, revealing a worldwide network of currents, that had been invisible!