1903.] 0. Little — Himalayan summer storms. 247 



July, 1903. In the former case the wind turned to northerly through 

 west and in the latter through east. The reason appears to be that the 

 cyclonic storm which developed subsequently over the north of the Bay 

 last year was a little more eastward than this year. 



In the previous paper I gave some facts showing the passage of the 

 disturbance on June 30th, 1902, over Bengal, and more detailed informa- 

 tion for Calcutta partly from personal observation. On that occasion 

 the disturbance began to affect weather at Calcutta about 5 a.m., and its 

 progress was shown by the continued fall of temperature. The disturb- 

 ance this year began about 5 p.m. and came on as last year with a rush 

 of wind from the north accompanied by light rainfall, some thunder and 

 a rapid fall of temperature. The fall of temperature was more rapid 

 than last year, and was in the course of an hour from 92° at 5 p.m. to 78° 

 at 6 p.m. This greater rapidity was partly due to the disturbance 

 occurring at the end instead of the beginning of the day. 



The barometer at Calcutta was only slightly affected and in much 

 the same way as last year. The small irregularities began about 1 P.M. 

 and a slightly more rapid rise than usual began about 5 p.m., followed by 

 a fall which was completed about 7 p.m. 



I have mentioned that since the commencement of the monsoon 

 season there have been several of these disturbances. There were, I 

 believe, between June 13th and July 23rd, no fewer than four, although, 

 with the exception of the one for which tables have been given above, 

 they were not of so well marked a character as to make them useful for 

 establishing the occurrence of such disturbances. They possessed, how- 

 ever, more or less distinctly the characters of the storms which have been 

 more fully described. These characters are — 



(1) A fall of pressure along the Himalayan range, followed by a 



rise, both the fall and the subsequent rise being apparently 

 unconnected with the pressure changes in progress on the 

 plains of India, and having a southward progressive motion. 



(2) An indraught from the plains towards the hills shown by 



strongish south-westerly winds in Northern India. 



(3) Unsettled weather in the Himalayas and adjacent plains, 



with numerous thunderstorms and a rapid fall of tempera- 

 ture. 

 The last of these appears to be due to a strong northerly or north- 

 easterly wind from Thibet, across the Himalayas into the upper atmo- 

 sphere of the Indian plains. 



It is not my intention to prove the existence of the smaller disturb- 

 ances. It will be sufficient for my purpose if I mention approximately 

 the dates of their occurrence, and these dates can be readily found from 

 J. ii. 34 



