546 TKANSACTIONS OF SECTION A. 



until eight kilometres was reached. In fact the isothermals at the higher levels 

 follow the general trend of the ground barometer, but the results are scarcely 

 sufficient definitely to regard this as more than a coincidence. 



The effect of solar radiation during the daylight hours on the temperature 

 of the upper layers was almost inappreciable in this series and also in the series 

 June 2 and 3, 1909. 



The curves show that there was no very considerable absorption in any one 

 layer, and it may be calculated numerically that the maximum effect of the 

 sun's rays during a March day would only be sufficient to raise the temperature 

 of the whole thickness of the atmosphere by a few degrees Centigrade. 



5. Temperature Inversions in the Rocky Mountains. By K. F. Stupart. 



6. The Effect of Radiation on the Height and Temperature of the 

 Advective Region. By E. Gold, M.A. 



If H c denote the height and T c the temperature of the layer at which the advective 

 region begins, then observations show (1) that H c is greater and T c less over anti- 

 cyclones than over cyclones ; (2) that H c increases and T c v probably decreases with 

 approach towards the equator. While the conditions (1) are temporary in character 

 and may be not due to but in spite of radiation effects ; (2) represents an approxi- 

 mately steady and permanent state in which radiation must play a predominant part. 

 The following conclusions have been reached by the use of the methods developed in 

 ' The Isothermal Layer of the Atmosphere and Atmospheric Radiation.' 



If the atmosphere be divided into two regions, in the upper of which the tem- 

 perature is constant, then for a given temperature distribution from the earth's surface 

 upwards, the excess of the radiation from the upper layer over the absorption by it of 

 terrestrial radiation, i.e., radiation from earth and lower atmosphere, increases if the 

 absorbing power, 6, increases (a) in the upper region alone, (/8) in the convective region 

 alone, (y) throughout the atmosphere. This means that so far as radiation from 

 terrestrial sources is concerned an increase in the absorbing power of the atmosphere 

 will bring about a decrease in the temperature T c and an increase in the height H c of 

 the advective region, provided the temperature in the convective region remains 

 unchanged. 



If the value of b remains invariable while the temperature in the convective region 

 increases, the values both of H c and of T c increase also. 



It appears therefore that we have here the basis of the explanation of the variation 

 with latitude. The increase in humidity towards the equator means an increase in & at 

 least in the lower part of the atmosphere, and therefore an increase in H c , a decrease 

 in T c . The increase in temperature, however, means an increase both in H c and in T c . 

 Thus the two effects reinforce each other so far as H c is concerned, while for T c they 

 are opposed. The results of observation are on the whole in accordance with this. 

 The change in H c is very marked, that in T c is slight. 



There is, however, another condition to be satisfied. The total radiation out to 

 space from the earth and atmosphere must balance the total absorption of solar 

 radiation by earth and atmosphere so long as the temperature of the earth remains 

 nearly constant. The exact distribution in latitude of the absorption is not known, 

 but it is certainly greatest at the equator and diminishes towards the poles. The 

 radiation must then also be greatest near the equator and must diminish pole- wards, 

 but the rate of variation with latitude will be smaller than for the absorption owing 

 to the transference of energy by oceanic and atmospheric currents. 



Now if the atmosphere is what is termed a ' gray ' body, i.e., if each layer of it 

 radiates throughout the spectrum with an intensity proportional to that of a black 

 body at the same temperature, any increase in b diminishes the value of the outward 

 radiation, and if the diminution is great enough to counterbalance the effect of an 

 increased surface temperature on T c , it will also counterbalance the effect of the in- 

 creased temperature on the outward radiation. There could not therefore under 

 these circumstances be a balance in the transference of energy since the outward 

 radiation would be at least as small near the equator as in higher latitudes. Thus 

 the atmosphere cannot be regarded as a ' gray body ' in strict calculations on the 



