Entropy as a function of temperature (black line) in a sub-region of the convective envelope of SSM. The value of entropy at the limit between radiative and convective zone is represented as a blue line. The average of entropy in the green shaded area is represented as a green line and the average of entropy at orange points is represented as a dashed orange line. The green area has a width of 10% of the total width of the CZ (roughly $\raisebox{1ex}{$2$}\!\left/ \!\raisebox{-1ex}{$3$}\right.$ of the mass of the CZ) and the orange points are located only every ten layers in the green area.