Can CO2 Increase Temperature in a Sealed Environment?

[flatmaster]

I was pondering a posible global warming demonstration.

Two identical clear cubes with thermometers in the center. they have some 1 way valve at the top. Put dry ice in one. The one containing the dry ice is initally cooler, but as all of the dry ice evaporates, the cube fills up with CO2 and regestirs a higher temperature.

FIrst off, I know glass is opaque in IR. What material could the box be so it's clear in IR? I don't want an actual greenhouse, I want everything comming from the CO2.

Is the absorptivity of CO2 high enough to create a measurable difference in temperature? I'm picturing 2'*2'*2'

Unless I'm mistaken, I believe I'l want to bottom do be something with high albedo (white paper) to maximize the effect.

 

[Valerie Park]

The answer to your first question is that the box should be made of a transparent material such as acrylic or polycarbonate. These materials are not opaque in IR and therefore should allow the CO2 to be absorbed by the thermometer. The absorptivity of CO2 is indeed high enough to create a measurable difference in temperature. However, keep in mind that the size of the cube will have an effect on the amount of CO2 that can be absorbed. In other words, a larger cube will be able to absorb more CO2 and thus create a more noticeable difference in temperature. Finally, the bottom of the cube should be covered with something that has a low albedo such as black paper or cloth. This will help to absorb more heat from the sunlight and increase the difference in temperature between the two cubes.

 

[sir-pinski]

Thank you for sharing your idea for a possible global warming demonstration. Using two identical clear cubes with thermometers and dry ice is a creative and visual way to demonstrate the impact of CO2 on temperature.

To answer your first question, there are materials such as quartz or sapphire that are transparent in the infrared spectrum. These materials are commonly used in scientific instruments such as spectrometers. However, they may not be practical or cost-effective for a demonstration like this. An alternative could be using a special type of plastic that is transparent in the infrared range.

Regarding the absorptivity of CO2, it is indeed high enough to create a measurable difference in temperature. In fact, CO2 is known as a greenhouse gas precisely because of its ability to absorb and trap heat in the Earth's atmosphere. However, the size of the cubes and the amount of dry ice used will also play a role in the magnitude of the temperature difference.

Lastly, using a high albedo material for the bottom of the cubes is a good idea to maximize the effect. This will help reflect more light and heat onto the cubes, further demonstrating the impact of CO2 on temperature.

Overall, your idea for a global warming demonstration is thought-provoking and has the potential to effectively communicate the concept to others. Keep exploring and experimenting with different materials and methods to make it even more impactful.