THE ANTI-TEADES OR PASSAGE WINDS. 185 



(119). Anti-Cyclones.— In (34) an Anti-Cyclonic system is described as 



an area of relatively high barometric pressure, 

 around which, in the Northern Hemisphere, the 

 wind blows with watch-hands, i.e., contrary to what 

 it does in a Cyclone, but drawing slightly otit from 

 the centre, as shown in the adjoining diagram. It 

 is conjectured that within such an area the air is 

 descending from higher regions, and spreads out 

 over the lower barometric areas surrounding it. 



Mr, Ley remarks : — " An Anti-Cyclone represents 

 the position of a downward movement of the air, 

 which has lost the greater part of its water vapour in previous Cyclonic 

 circulations. In the district, therefore, near the central calm of an Anti- 

 Cyclone, the currents take up instead of precipitating vapour ; this explains 

 jvhy it has no principle of progressive development (or forward movement). 

 The Anti-Cyclone presents a great contrast to the Cyclone in this respect, 

 that instead of shifting their geographical position rapidly, they are ex- 

 ceedingly sluggish in their movements ; and, indeed, frequently remain 

 stationary for a very considerable period. 



(120.) " Here the reader is warned against another possible misappre- 

 hension. The terms ' Cyclone ' and ' Anti-Cyclone ' do not refer to the 

 actual level of the barometer within the areas to which they are applied, 

 but to its level relatively to the level in surrounding districts. The observer 

 may find the mercury in his barometer above its mean height (23), and yet 

 may possibly be situated at the centre of a Cyclonic system at the time, 

 because the mercury may be still higher at all stations at a certain distance 

 from his own. Contrariwise he may find the mercury in his barometer below 

 the mean, and yet may be at the centre of an Anti-Cyclone, because the 

 barometers on all sides of his station may have lower readings at the time 

 than his own." 



(121.) Captain H. Toynbee, in his pamphlet " Weather Forecasting for 

 the British Islands," published in 1890, remarks : " It is clear that winds 

 from all directions blow in connection with each of these systems. For 

 instance, both have a South wind, but with very different characters. In 

 the case of a Cyclonic or low barometer system, the South wind is on the 

 Eastern side, where the air is rising and having its vapour condensed into 

 cloud and rain, by which heat is given out. In the case of an Anti- 

 Cyclonic or high barometer area, the South wind is on the Western side, 

 where the air is descending and is comparatively cool and dry, having a 

 tendency to take up moisture instead of giving it out. 



" Between the South wind on the Western side of an Anti -Cyclone and 

 the South wind on the Eastern side of a distant Cyclonic area, there wili 

 be a prevailing Southerly wind, and in passing from the high to the low 

 barometric area, a position will be come to where the air will cease to 

 descend. As the low pressure area is approached, the ascending air will 

 be entered, and clouds and rain will be experienced. 



" Experience shows that when a storm-centre has passed away, it is 

 frequently followed by a mere ridge of relatively high barometer ; between 



N. A. 0, 25 



