Meteorological observations and essays / By John Dalton.

  • John Dalton
Date:
1834
Catalogue details

Licence: Public Domain Mark

Credit: Meteorological observations and essays / By John Dalton. Source: Wellcome Collection.

    223/280 (page 197)
    TO THE SECOND EDITION. Norr [A] SEE pace 40. From the table, at page 40, it may be seen the clouds are lowest in the three first and three last months of the year, evidently pointing out tem- perature as the regulating cause. Indeed the clouds are seldom a mile high in our climate in winter ; in summer they may perhaps occasionally be two or three miles high. The thickness of a stratum of clouds, or distance from the under to the upper sur- face, is also variable from a few yards to three or four hundred or more ; at least it is so with such as | have had occasion to observe. A stratum of cloud of greater depth is probably of rare occurrence anywhere ; it would produce a greater degree of darkness on the earth’s surface than is ever ob- served. In cloudy and rainy weather, in the sum- mer season, when vapour is abundant, the process of nature seems to be to produce two, three, or more parallel strata of clouds, with clear transpa- rent strata of air intervening : when rain commences from the uppermost cloud, it causes an extension of the cloudy strata into the clear strata, till the