Science from home: Temperature and density

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What you need:

  • Cups (Glass will work best)
  • Cold water
  • Hot/warm water
  • Food coloring
  • A waterproof layer that covers the mouth of the cup (example: Plastic bag/cardboard)
  • Flat container, just in case (example: casserole dish)

Steps:

  1. Since we are working with water, place a container (like a casserole dish)
  2. Fill one cup with cold water
  3. Fill another cup with hot water (if using plastic cups, think about using warm water so the cup does not melt)
  4. Add a few drops of food coloring into the cold water
  5. Add a few drops of a different color food coloring in the warm/hot water
  6. Cover/ seal off the mouth of the cold water using something like a sheet of plastic, plastic bag, or thick piece of cardboard
  7. Place the cup of cold water upside down directly on top of the cup of hot water (with material used in step 6 as a boundary completely covering the mouth of both cups)
  8. Make sure that the edges of the cups are perfectly lined up
  9. Carefully remove boundary layer between the cups (that was used in step 6)
  10. Watch what happens
  11. Repeat steps 1-5
  12. Cover/ seal off the mouth of the hot water using something like a sheet of plastic, plastic bag, or thick piece of cardboard
  13. Carefully place the cup of hot water upside down directly on top of the cup of cold water (with material used in step 12 as a boundary completely covering the mouth of both cups)
  14. Make sure that the edges of the cups are perfectly lined up
  15. Carefully remove boundary layer between the cups (that was used in step 12)
  16. Watch what happens

The science and how this applies to our atmosphere:

Our atmosphere acts like a fluid. So, we can use water to see how it it reacts, and in this case how it reacts to different temperatures.

Did you notice that when the warm was on top and the cold was on bottom, the two did not mix?

That is because warm air is less dense than cold air. So naturally, it will sit on top of cold air (in water in the experiment). When warm air molecules are not being forced upward, it represents a stable atmosphere and calm weather.

There was a very different response to the warm cup on bottom and the cold cup on top.

Since the cold water is more dense that the warm water, it rushed to the bottom of the cup and pushed the warmer water to the top. As a result, the two colors mixed and gave us purple water.

This is a process that happens in our atmosphere when something like a cold front moves through. A cold front means that we have colder air moving in. Since the colder air is more dense, it will cut under the warmer air and force it upward.

This upward motion of air molecules creates instability. When moisture moves into an unstable atmosphere, we get thunderstorms.

Copyright 2020 Nexstar Broadcasting, Inc. All rights reserved. This material may not be published, broadcast, rewritten, or redistributed.

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