1. The problem statement, all variables and given/known data I’m trying to figure out the equation for sol-air temperature and don't undertand how to find ΔR. 2. Relevant equations tsa=to+(αIt-εΔR)/ho tsa - sol-air temperature to – ambient air temperature (outside dry-bulb air temperature) α – surface solar absorptance (inverse of the product’s listed solar reflectance) It – total solar radiation incident on the surface (can get from solar radiation ground monitoring sites) ε – surface emittance (can get from product data sheet) ΔR – net radiation exchange (difference between the long-wave radiation received and emitted by the surface) ho – external surface heat transfer coefficient (can get from several places on the web) 3. The attempt at a solution I think I understand most of the variables (please correct me if I’m wrong) except, as stated above, how to find ΔR. Do I calculate the emissivity of the sky and then multiply the emittance of the product, then subtract the answer from the sky emissivity?