512 CHANGE OF TEMPERATURE WITH HEIGHT DURING ANTI-CYCLONES. 



From all these observations — both at varying heights in Switzerland and in rapid 

 changes from foggy to dry air at the upper surface of clouds — it seems well established 

 that, in the class of anti-cyclones which bring out the Ben Nevis barometer higher than 

 the true pressure when reduced to sea-level, the cold of the lower atmosphere is con- 

 fined to a small vertical height, and that the reversal of temperature gradient, indicated 

 by a high-level station being warmer than a low, all takes place in the cold damp air, 

 or just immediately above it ; the great mass of warm dry air which forms the body 

 of the anti-cyclone having normal vertical temperature gradients, indeed showing, if 

 anything, a decrease of temperature with height rather more rapid than usual. How 

 far the converse of this holds — that in a cyclonic area, when the Ben Nevis barometer 

 comes out lower than the true pressure at sea-level, the intermediate air is colder 

 than the mean of summit and base — has not yet been determined. The more rapid 

 changes of cyclonic weather, and the frequency of high winds, with their purely 

 mechanical depression of the barometer, introduce complications that are absent in the 

 anti-cyclone. 



