What is the effect of temperature on the density and hence weight of air?
"warm air rises, cold air sinks..." Gee, thanks. THIS, we all know. How about something helpful? I -do- know that at 20 degrees (68 degrees F), air at sea level can be assumed to weigh approximately 1.2 ounces per cubic foot (based on the CRC Handbook of Physics And Chemistry's information on Nitrogen, which being roughly 80% of our atmosphere seemed a reasonable source for an approximation). What I need to know, and meant by the question, was more along the lines of "How much effect does changing the temperature of the air have on the weight of the air", ie, if it's a really hot day in the desert then how much lift am I going to lose.