ME. H. E. BLANFOED ON THE WINDS OF NOETHEEN INDIA. 
591 
nation of the present case ; but the climatal conditions of a European hill-tract are so 
different from those of the Gangetic plain and the Himalayan boundary chains, that 
conformity of the local empirical laws of the two regions is not to be expected. M. Hann 
has not suggested any physical cause for the difference he has observed in the tempe- 
rature decrements with south-west and north-east winds, and I may therefore be per- 
mitted to suggest one in the difference of their humidity ; since the continual upward 
diffusion and condensation of water-vapour must tend to equalize the temperatures of 
the lower and higher strata, and this tendency will be the greater the higher the humi- 
dity of the air — that is, the nearer it is to saturation. In the case of the Himalayan 
stations there appears to be a certain inverse ratio between the relative humidity of the 
atmosphere and the difference of temperature at the upper and lower stations — not, 
indeed, such as to explain the whole of the variation, but such as to indicate that the 
condensation of vapour exercises an important influence on the phenomenon. This is 
shown in the accompanying diagrams (figs. 2 & 3), which give the curves of mean 
Fig. 2. 
D J FMAMJ JASOND 
Fig. 3. 
humidity at two of the higher and two lower stations, together with those of the tem- 
perature differences between the pair of stations contrasted. 
