The air inside a hot air balloon has an average temperature of 71.7° C. The outside air has a temperature of 11.1° C. What is the ratio of the density of air in the balloon to the density of air in the surrounding atmosphere?

Answer 1

Since the pressure is very nearly the same inside and outside the balloon, density is inversely proportional to absolute temperature.

rho_inside/rho_outside = T_outside/T_inside
= 284.3/344.9 = 0.824