THE BEARING OF POLAR METEOROL 

 ON WORLD WEATHER 



H. H. Clayton 



The Circulation of the Air between the Equator 

 AND the Poles and the Factors That Modify It 



If one constructs an elongated glass box and places under one 

 end a block of ice and under the other end a metal vessel filled with 

 hot water, as illustrated in Figure i, the air in the box will begin 

 to circulate in the manner shown by the arrows. This circulation 

 may be made visible by 

 introducing smoke or fine 

 dust. 



If there were no other 

 factors than polar ice and 

 equatorial heat, there would 

 be a circulation somewhat 

 of this nature between the 

 equator and each pole ; that 

 is, there would be an air 

 current flowing along the 



surface of the earth from the poles toward the equator and a 

 return current above. There would be an area of high pressure 

 over the north pole and one over the south pole, and the pressure 

 would decrease toward the equator, where it would be low. Such 

 a simple circulation is interfered with by a variety of conditions: 

 (i) by the irregular distribution of land and water; (2) by the move- 

 ment of the water; (3) by the rotation of the earth; (4) by the de- 

 creasing density of the air with increasing height; (5) by irregular 

 radiation and absorption in the atmosphere, owing chiefly to its 

 water-vapor content. 



Fig. I — Circulation of air in a closed glass tank heated at 

 one end and cooled at the other. 



Distribution of Land and Water 



The influence of the irregular distribution of land and water, as 

 is well known, operates as follows. Land surfaces are heated under 

 the direct rays of the sun more rapidly than water surfaces and cool 

 more rapidly at night by radiation into space. This alternating 

 heating and cooling of land surfaces causes inblowing winds (sea 

 breezes) by day and outblowing winds (land winds) at night. The 



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