Try This: See Convection Currents!
We often don't see what affects our daily lives, like air. When we think of air and weather, we may often think about high- and low-pressure systems. Wouldn’t it be cool if we could actually visualize these high- and low-pressure systems and the convection currents that result when they meet?
With a few things that may already be in your kitchen, you can create your very own model of convection currents, and the results are quite stunning!
Here’s what you need:
- A clear tub or bowl
- A couple cups or two stacks of books to hold the clear tub or bowl high enough that you can slide a mug underneath
- A mug
- Food coloring of two different colors
- Hot and cool water
Here’s what you do:
1. Use a couple cups, or two stacks of books, to set the clear tub or bowl just high enough that you can slide your mug underneath. After you’re sure the mug will fit underneath, remove it and set it aside.
2. Fill the clear tub or bowl with cool, not cold, water.
3. Fill your mug with hot water (like from an electric kettle, or the stove), or fill the mug with water and heat it in a microwave. Then move your mug of hot water near the raised tub.
4. Put one drop of the same color of food coloring at the bottom of the far right and far left side of your tub. It's important to leave an empty space in the middle.
5. Get your second color of food coloring ready. In the space between the two dots of food coloring, add a third drop but of a different color.
6. Slide the cup of hot water under the middle of the bowl or tub, below where the third drop of food coloring was placed.
7. Observe as the heat from the hot water in the mug creates convection currents in the tub!
Liquids and gasses are both fluids. The water in the tub represents the air around us in the atmosphere. At first the water in the tub was all about the same, and the different drops of food coloring acted about the same. When the hot water source was added below the middle of the clear tub, the heat energized the water and food coloring above it making the water and food coloring rise.
This faster moving area of fluid created an area of lower pressure. The fluid around it is cooler, moving more slowly, and of higher pressure. As the fluid rises creating a lower pressure system, the higher pressure system that surrounds it moves into the lower pressure space.
In the activity, this resulted in convection currents, specifically currents we could see due to the food coloring. Though we used a heat source to create our area of low pressure in this activity, this is not always the case in the air that surrounds us. In our atmosphere we cannot see these convection currents but we can feel them as wind or see the clouds and precipitation that they can cause!