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.