NO. 4 TEMPERATURE VARIATIONS IN THE NORTH ATLANTIC 305 



actually penetrates into our atmosphere, it is only about one third, 

 or a little more than 20 per cent of the total solar heat energy, 

 reaching- our outer atmosphere, that penetrates to the earth and is 

 absorbed directly to produce heat on its solid and liquid surfaces 

 [cf. Abbot, 1917]. The rest of the 60 per cent of energy is ab- 

 sorbed in the atmosphere itself. Any change in the solar radiation 

 of energy must consequently have a much greater effect on the 

 atmosphere as a total, than at the surface of the earth. 



The greater part of the solar energy received by our planet must 

 naturally be absorbed in the troposphere, as it represents by far the 

 greatest mass of the atmosphere. 



It is this continuous supply of solar energy that creates the 

 circulation of the atmosphere. Any change in this supply must 

 consequently cause changes in the circulation. An increased supply 

 of energy will naturally cause an increased circulation, and vice 

 versa. The atmospheric circulation is due to differences in pressure, 

 and changes in the circulation must consequently be due to changes 

 in the distribution of pressure. At the earth's surface we may 

 therefore expect to see the first effect of changes in solar radiation 

 in the pressure, as we have really also seen in many cases {e. g., 

 at Batavia). The results of all our investigations seem to agree 

 that the effect of the variations in solar radiation are first observed 

 in the distribution of pressure, when the observations are made at 

 the earth's surface. 



The explanation is probably : Changes in the solar radiation 

 cause temperature changes in the atmosphere, chiefly in the tropo's- 

 phere, and at heights that may possibly to some extent be deter- 

 mined by the cloud-formation. 



The temperature changes in these layers of the atmosphere will 

 cause movements of the air, which will also cause changes in the 

 distribution of pressure at the earth's surface, and disturbances in 

 the lower strata of the troposphere. An increased supply of energy 

 will cause increased movement in the atmosphere, and this will 

 again effect the temperature at the earth's surface, differently in 

 the different regions, as we have mentioned before. 



