1904.] 0. Little — The Himalayan summer storm of Sept. 24th, 1903. 175 



The rainfall statistics in the above table have been prepared in the 

 same way as in previous papers. As I have said before, thunderstorms 

 with irregular changes of pressure and temperature and variable rain- 

 fall are the chief features of the passage of these disturbances over 

 Bengal, and that it is advisable on that account to give averages instead 

 of individual observations. To obtain the rainfall in North Bengal, for 

 example, on the 25th September, the rainfall reported from the various 

 Observatories in that division, 7 in number, has been added together. 

 The average fall in North Bengal for the 24 hours preceding 8 a.m. on 

 the 25th was 2*01 inches. I have retained the totals as they serve to 

 magnify the comparison which the table is intended to indicate. 



It will be seen that rainfall in some quantity began in Assam on 

 the 23rd and continued until the 26tli. In North Bengal the days of 

 heaviest rainfall were the 25th and 26th , in South-west Bengal the 26th ; 

 and there was very little rain in Orissa until the 28th. Considerable 

 increase of rainfall is shown for Bihar on the 25th, and in the United 

 Provinces on the 26th —an increase which occasional remarks in the 

 Daily Weather Report show to have been associated with thunder- 

 storms along the Himalayan range. It may be noticed that a consider- 

 able proportion of the rainfall in the above table fell before the 26th or 

 27th, the dates on which, according to the Pioneer, the Meteorological 

 Bureau arrived at the conclusion that fine weather conditions were be- 

 coming established over Upper India. 



It may be noticed that the rainfall was heavy on this occasion at 

 neither Darjeeling nor Oherrapunjee, But some increase is shown at 

 both places, and the reason why there is so much variation in rainfall 

 with disturbances, otherwise similar in character, probably arises from 

 the irregular distribution of thunderstorms. If a thunderstorm occur- 

 red near Oherrapoonjee the rainfall is likely to be much more heavy 

 than if the storm were distant. Another cause, which on this occasion 

 may have influenced the fall at Oherrapunjee, is that there was little 

 or no indraught up the Brahmaputra Valley towards the east end of 

 the Himalayan range. The indraught towards the hills was confined 

 more to part of the range north from Bengal and Bihar, and the 

 heaviest falls appear to have been on the southern slopes of that part 

 of the range. 



I have pointed out that the disturbance, as it passed over Bengal, 

 was similar, in its main features, to the disturbances which occurred on 

 the 30th June and 12th August 1902, and the 9th July 1903; audit has 

 been seen from the remarks of the Pioneer that it was followed by 

 exceptional weather in part of Northern India. It has also been seen 

 that over the southern seas, and in fact over the whole of the Bay of 



