a. The air temperature of the Earth's atmosphere increases linearly with altitude h, T = T₀ + αh. In this case, the relative temperature change αh/T₀ remains much less than unity. The mean free path of air molecules λ, the mass of each molecule m, and the number of molecules per unit volume of air n. Estimate the heat flux density to the Ground. Will the density of this flow change if the number of molecules per unit volume of air increases?
b. How many times is the thermal conductivity of hydrogen greater than that of air? The radius of hydrogen molecules is 0.14 nm, and the radius of nitrogen and oxygen molecules is 0.18 nm. The temperature of the gases is the same.