Page:Proceedings of the Royal Society of London Vol 69.djvu/93

Rh The climatic conditions at a place like Kew, for example, which is not far from the sea, and which may be regarded (according to fig. 1) as having an original planetary temperature range of 10'6 F., and a resultant range of 24 F., may be contrasted with those for such a station as Nertchinski-Zavod,* at about the same latitude, with a range of over 120 F. Its maximum is reached by the middle of July, consequently the composition of the original planetary range with the range due to the surrounding region is almost algebraical. On that understanding, and assuming that the planetary range is the same as that at Kew, we find that the influence of the surrounding land at Nertchinski-Zavod is to increase the range by 110 F., whereas the effect of the sea at Kew only adds 13'6 F. to the range, i.e., less than one-eighth of the land effect on the same latitude. The corresponding diagram would be as represented in fig. iii upon a scale of temperatures one-third of that of the other figures.

FIG. iii.

B

A &-3F. C

It is not, of course, a legitimate assumption that the planetary range corresponding to the latitude of Kew is accurately represented by 10 '6 F., which requires only to be compounded with the sea effect to produce the resultant oscillation. The resultant effect at Kew is probably resolvable into three components one the original planetary effect with its maximum in June, a second due to the surrounding land with its maximum in July, and the third due to the sea with its maximum in August. The precise epoch of maximum of the land effect, which would identify the direction of its line on the diagram, and the actual magnitude of any one of the component effects, which would fix the position of the lines in the diagram, are not at present determinate, but their extreme limits are known.


 * Atlas Cliraatologique de 1'Empire de Russie. St. Petersburg, 1900.