12 0. Little — The recent excessive heat in Bengal, [No. 1, 



Maximum temperature over Bengal, as may be seen from the table 

 given above, was from the middle of April till nearly the end of May 

 continuously above the normal at times by as much as 15°. 



This high temperature appears to me to be fully accounted for by 

 the warmer air above, owing to which convection was seriously impaired 

 and the air below had to be heated more than usual before its buoyancy 

 was sujQficient to carry it away from the earth's surface. 



I have pointed out as clearly as I can, and I hope I have made it 

 manifest that the above explanation rests upon inferences from what 

 I believe to be facts. The main fact is the westerly wind, and the main 

 inference is that the temperature of that wind was higher than that of 

 the more usual north-westerly wind. No one can say that the inference 

 is a wrong inference, because no information has been collected regard- 

 ing the condition of the upper atmosphere. But there are other facts 

 which support the inference that the upper air over Bengal was warmer 

 than usual during the past hot season, and these I give for what they 

 are worth in connection with the present argument. 



I have already quoted the opinion of a distinguished meteorologist as 

 to the condition of the upper air favourable for the development of thun- 

 derstorms. What he requires is " a strong and even abnormal temperature 

 gradient." If, then, the upper air is warmer than usual, it is evident that 

 the abnormal temperature gradient would be more difficult to bring 

 about. The temperature below would have to be higher, and when thun- 

 derstorms did occur it might naturally be expected that as thunder- 

 storms they would not be on the same grand scale. It is impossible to 

 record all the characteristics of thunderstorms or even many of them, 

 and the items of information which are generally available for those 

 who have not been in touch with the storms are the rainfall, the change 

 of temperature and occasionally the strength of the wind. Taking then 

 the rainfall and the change of temperature as tests of the character of 

 the numerous thunderstorms which have occurred in Bengal during 

 the past season, th6re can, I think, be no question but that according to 

 these tests thunderstorms have been a comparative failure. The 

 rainfall has been much lighter than usual, and many thunderstorms 

 have caused no rainfall at all. Temperature though it fell during these 

 disturbances, changed by smaller amounts than we generally experience. 

 The comparative failure of thunderstorms at Calcutta must have been 

 observed by all, and any information that has reached me froni other 

 parts of Bengal has been to the same effect. I was informed by a resident 

 at one of the headquarter stations that on one occasion while the ground 

 temperature below was high, there appeared daily for a week the cloud 

 which is the first sign of the coming thunderstorm. As day after day 



