Note 31 — The Establishment of Solar Climates.

At the culmination of the Ice Age evaporation reached its minimum, and hence precipitation was also at a minimum. Since that Age evaporation has slowly increased; the amount of moisture in the atmosphere being dependant upon its temperature, this amount has also increased. The aggregate amount of evaporation and the aggregate amount of precipitation is slowly increasing, and has the moderate limit fixed by natural laws for increase of mean temperature. Mars appears to have progressed further in this mean condition than the earth. The smaller mass partly accounts for this.