Uploaded July 2024 | Updated September 2026, 2 weeks ago
Thermal gradients happen when 2 or more materials separate at different temperatures. In fluids like air or water, colder fluids are more dense and settle, while warmer fluids are less dense and rise.
Often when this happens in air, you'll see storm fronts form. Much of our weather is based on the interaction of air at different temps and humidity. This would model a calm night with little wind to mix the two layers around.
In this demo, I filled a large glass jar with hot tap water. After placing the large tea bag in it, I left it in the sink to steep. I did not shake or mix this jar at all, so the fluids have been very still.
The cool metal of the sink conducts heat away from the bottom of the jar, resulting in a region of cooler tea. The cooler tea is desner than the warm water. The temperature and mixture density is great enough to result in a separation between the two liquids! Black tea is ~1.03 g/cm3, while water is ~1g/cm3.
As the whole jar cools down, the tea mixture will diffuse up. This takes about an hr.
If you want to see the density of your favorite drinks, check aqua-calc.com/page/density-table
If you'd like to see more, leave a comment below about what you would change! I have a couple ideas, but I'd like your feedback as well.
Thermal gradients happen when 2 or more materials separate at different temperatures. In fluids like air or water, colder fluids are more dense and settle, while warmer fluids are less dense and rise.
Often when this happens in air, you'll see storm fronts form. Much of our weather is based on the interaction of air at different temps and humidity. This would model a calm night with little wind to mix the two layers around.
In this demo, I filled a large glass jar with hot tap water. After placing the large tea bag in it, I left it in the sink to steep. I did not shake or mix this jar at all, so the fluids have been very still.
The cool metal of the sink conducts heat away from the bottom of the jar, resulting in a region of cooler tea. The cooler tea is desner than the warm water. The temperature and mixture density is great enough to result in a separation between the two liquids! Black tea is ~1.03 g/cm3, while water is ~1g/cm3.
As the whole jar cools down, the tea mixture will diffuse up. This takes about an hr.
If you want to see the density of your favorite drinks, check aqua-calc.com/page/density-table
If you'd like to see more, leave a comment below about what you would change! I have a couple ideas, but I'd like your feedback as well.
