The entropy of a system of n spins with magnetic moment m, where 2s is the spin excess (n is approximately sigma = ln[g(n, s=0)] - 2s^2/n, for small s and large n. given that the energy of the state with spin excess 2s in a magnetic field b is = -2smb, calculate the average value of the fractional magnetisation, 2(s)/n, as a function of temperature.

answer: the exterior temperature of commercial jet planes as they leave the stratosphere and return to the ground increases steadily.

explanation:

the lower most layer of atmosphere is troposphere which extends from 0 to 12 km above the surface of the earth. the temperature initially decreases as distance is increased from the earth's surface. commercial jets fly in lower part of the stratosphere. the stratosphere extends upto 50 km. the temperature in stratosphere starts rising again due to presence of ozone which traps the uv rays.

thus, when the planes leave the stratosphere and return to the ground, the exterior temperature increases steadily.