554 T. C. CHAMBERLIN 
incoming rays and the consequent reduction of the thermal 
gradient of a vertical column of the atmosphere. As a result 
there is less effective tendency to convection and less discharge 
of heat from the atmosphere. 
In high latitudes, besides this effect, it is also to be noted 
that with an increase of the absorptive capacity of the upper 
atmosphere, rays that previously passed through the higher strata 
with little absorption are arrested and contribute heat to the 
upper air. The same is true of morning and evening rays at high 
elevations. 
In the case of the outgoing rays, which are absorbed in much 
larger proportions than the incoming rays because they are more 
largely long-wave rays, the tables of Arrhenius* show that the 
absorption is augmented by increase of carbonic acid in greater 
proportions in high latitudes than in low; for example, the 
increase of temperature for three times the present content of 
carbonic acid is'21.5 per cent. greater between 60° and 70° N. 
latitude than at the equator. The maximum thermal effects 
also lie in higher latitudes for the summer months than for the 
winter months. On the other hand, when the carbonic acid is 
reduced to 0.67 of the present content, the maximum winter 
variation is felt between 30° and 4o° N. latitude. If the car- 
bonic acid be further reduced, the maximum variation found by 
extrapolation falls at and below 30”, the latitude of the Carbon- 
iferous glaciation. It is not intended, however, to imply that 
this would be sufficient in itself to produce that glaciation. 
An atmosphere having a relatively large percentage of carbon 
dioxide and water, 7. ¢., an absorptive atmosphere, has a higher 
heat content than a non-absorptive one, and its circulation in 
latitude more effectually equalizes the temperature with the same 
degree of movement. 
Similar considerations are applicable to the effects of land 
and water areas. In so far as the atmosphere absorbs the incom- 
ing rays in passing through it, the amount that reaches the sur- 
face of the earth is reduced. To this extent the possibility of 
~IZOC. cit., Pp. 200: 
I 
