Difference between revisions of ".Mzc2.NzQ5Ng"
(Created page with "[ 51 ] on the higher ones. I shall add, that though my hy- grometer was exposed to the open air on the moun- tain, as it was in the plain, yet it was not so much insulated t...") |
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barometer The difference observed, however, is so | barometer The difference observed, however, is so | ||
considerable that, notwithstanding the concurrence of | considerable that, notwithstanding the concurrence of | ||
| − | all these | + | all these particular causes. I cannot bot ascribe it in |
some measure to that general one which I have | some measure to that general one which I have | ||
suspected, namely, that there is comparatively a less | suspected, namely, that there is comparatively a less | ||
| Line 12: | Line 12: | ||
parts of the atmosphere. | parts of the atmosphere. | ||
| − | 101. The | + | 101. The observation of the 13th of September |
seems likewise to throw some light upon the phae- | seems likewise to throw some light upon the phae- | ||
nomena of dew. We know that when the sky is | nomena of dew. We know that when the sky is | ||
| − | cloudy, there is | + | cloudy, there is little or no dew, and it has likewise |
been observed from this very circumstance, that the | been observed from this very circumstance, that the | ||
| − | air is not | + | air is not so much cooled after sun-set. The cause |
of these differences appears to n1e to be, that when | of these differences appears to n1e to be, that when | ||
| − | there are no clouds in the air at | + | there are no clouds in the air at sun-set, or when |
they are dispersed the heat of the inferior air, and | they are dispersed the heat of the inferior air, and | ||
that which rises from the earth, dissipates itself into | that which rises from the earth, dissipates itself into | ||
the superior regions, and then the vapours which are | the superior regions, and then the vapours which are | ||
dispersed throughout the air condense and all down | dispersed throughout the air condense and all down | ||
| − | again in dew | + | again in dew; but when the clouds are continued, |
| − | and thus | + | and thus separate the inferior from the superior air, |
they prevent this dissipation of the heat, and the va- | they prevent this dissipation of the heat, and the va- | ||
pours remain suspended. And if the sky grows | pours remain suspended. And if the sky grows | ||
| − | cloudy some hours after the | + | cloudy some hours after the setting of the sun, and |
after the heat has sensibly diminished in the inferior | after the heat has sensibly diminished in the inferior | ||
air, it encreases again in it; because the heat, which | air, it encreases again in it; because the heat, which | ||
Revision as of 15:24, 3 December 2017
[ 51 ] on the higher ones. I shall add, that though my hy- grometer was exposed to the open air on the moun- tain, as it was in the plain, yet it was not so much insulated there, being tied to the box of my portable barometer The difference observed, however, is so considerable that, notwithstanding the concurrence of all these particular causes. I cannot bot ascribe it in some measure to that general one which I have suspected, namely, that there is comparatively a less degree of humidity in the upper than in the lower parts of the atmosphere.
101. The observation of the 13th of September seems likewise to throw some light upon the phae- nomena of dew. We know that when the sky is cloudy, there is little or no dew, and it has likewise been observed from this very circumstance, that the air is not so much cooled after sun-set. The cause of these differences appears to n1e to be, that when there are no clouds in the air at sun-set, or when they are dispersed the heat of the inferior air, and that which rises from the earth, dissipates itself into the superior regions, and then the vapours which are dispersed throughout the air condense and all down again in dew; but when the clouds are continued, and thus separate the inferior from the superior air, they prevent this dissipation of the heat, and the va- pours remain suspended. And if the sky grows cloudy some hours after the setting of the sun, and after the heat has sensibly diminished in the inferior air, it encreases again in it; because the heat, which continues to rise out of the earth, is accumulated in the inferior air. This appears in the observation I am speaking of. The clouds having been sepa- H 2 rated
