l6o HUMPHREYS: METEOROLOGICAL PARADOXES 



air, as we know, is driven up by the surrounding denser air, and 

 dynamically cooled, but the air that drives it does so by dropping 

 to a lower level, where it is more or less compressed and corre- 

 spondingly warmed. In other words, while the particular air 

 that was heated rises and gets colder than it was initially, other 

 air that was not heated at all falls lower and thus gets warmer. 

 It is not the air that is heated, but air that is not heated, that 

 gets warmer. 



NOT AIR THAT IS CHILLED, BUT AIR THAT IS NOT CHILLED IS 



THEREBY COOLED 



The explanation of this paradox is very similar to that of the 

 one just given, and is equally simple. As the chilled air descends, 

 certain other air is thereby raised and dynamically cooled. That 

 is, while the particular air that was cooled descends and thus 

 gets warmer than it was originally, other air that was not chilled 

 at all is forced up, expands, and gets colder. It is not the air 

 that is chilled (unless it happens to be on or near the surface 

 where it cannot fall to a lower level) but air that is not chilled, 

 that gets colder. 



MIXING BRINGS THE AIR TO A NON-UNIFORM TEMPERATURE 



To the laboratorian familiar with beakers and calorimeters; 

 to the housewife skilled in the art of the cups and kettles; and 

 to all the rest of us, nothing is more certain — nothing more in 

 accord with daily experience — than that vigorous stirring es- 

 tablishes a uniform temperature throughout the agitated medium. 

 And indeed this conclusion is quite correct in respect to the par- 

 ticular things we are likely to have in mind, but it does not apply 

 to the open atmosphere. In fact if the temperature of the at- 

 mosphere were uniform through any considerable altitude, a 

 complete stirring of it would immediately destroy this uniformity. 



Let, then, the atmosphere, whatever its initial temperattue 

 distribution, be thoroughly mixed without the addition or sub- 

 traction of heat. This will bring it into such state (that of neu- 

 tral equilibrium) that any portion of it on being adiabatically 

 moved to a different place will, on arriving at that place, have 

 the same temperature as the then adjacent air at the same level. 



