The envelope temperature, atmospheric bottom temperature and surface temperature difference as a function of the accretion time-scale (a measure of the luminosity through L = GMṀ/R). The envelope temperature is close to 3,500 K for all values of the accretion time-scale. Matching this temperature at the top of the atmosphere leads to atmospheric temperatures above 10,000 K for short accretion times (high luminosities) and 4,000 K for long accretion times (low luminosities).