SOME WORLD'S WEATHER PROBLEMS 217 



be seen further on, its application to weather changes of longer 

 duration is equally appropriate. 



Enough perhaps has been written about this oscillatory 

 pressure change to give the reader an insight into its bearing on 

 the progress of meteorology during the present century. 



Its detection opens up many fields for future research. Not 

 the least of these will be the determination of the height above 

 the earth's surface to which it can be traced. The highest 

 station at which it has been found so far is Leh, in India, which 

 stands at an elevation of 11,503 ft. above sea level. From an 

 atmospheric point of view, this is not a great altitude ; but it 

 may be possible, when systematic kite flying is a matter of 

 daily routine, to examine their records from this special point 

 of view. 



A piece of work which undoubtedly calls for immediate atten- 

 tion is the thorough examination of the pressure changes at every 

 station which possesses a series of barometric observations. The 

 map accompanying this article is only a very rough approxi- 

 mation of the prevailing conditions gathered from a discussion 

 of ninety-five stations distributed over the globe. The paucity 

 of observations in some regions, especially the oceans, is sufficient 

 in itself to indicate the tentative nature of the pressure distribution 

 here displayed ; but the map will serve its purpose if it indicates, 

 as I think it does, the regions where observations are most 

 wanted. We are here truly in the domain of World Meteorology, 

 for an island, ever so remote from the mainland, becomes a unit 

 of the first importance in the determination of the extent and 

 intensity of these pressure changes. Islands may not be ideal 

 places for meteorological observers to live on, but they are 

 perfect stations for studying the movements of the atmospheric 

 currents, which are there unhampered, and therefore not rendered 

 so complex by the presence of large tracts of land or lofty 

 mountains. 



Any one who has examined a long series of barometric 

 observations will have noticed that, in addition to the short 

 waves of fluctuation just described, there are others of much 

 longer duration. Those changes are not due to any defects in 

 the measuring instruments, but are actual variations due to our 

 atmosphere. The reader is probably better acquainted with 

 somewhat similar variations in the case of rainfall ; but, as I have 

 previously stated, rainfall being an effect of pressure, the pressure 



