1. The problem statement, all variables and given/known data Hello, so I'm in a class that is building sensors and sending them up in a weather balloon. For my project, I am wanting to quantify the greenhouse effect by measuring the intensity of infrared light emitted as thermal radiation from the Earth as a function of height-- the idea is that as the balloon rises, some of the IR light is absorbed by water vapor and other greenhouse gases, causing intensity to go down. 2. Relevant equations From Wein's displacement law, I know emitted radiation will be about 10 μm. I calculated the change in intensity due to spherical geometry causing an increase in area. 3. The attempt at a solution I have a couple questions about the experiment and one problem. 1. It seems like the intensity of far-IR light from the sun is negligible compared to that radiated from the Earth. Is this a reasonable assumption? 2. I am unable to find data on emission of water vapor. Will the light absorbed be re-emitted at the same wavelength, skewing our data? This is my biggest concern, because it would basically invalidate the experiment. Finally, we have been searching for a circuit component that detects light intensity in the 10 μm range. Have any of you used one in this range? It must detect intensity of the wavelength. Thanks you so much!