DOI Seite / Zitierlink:
https://doi.org/10.11588/diglit.20140#0570
THE ISOTHERMAL TABLES.
Materials. Tables for the yeaY and the seasons.
The calculation of the isothermal tables is based upon the means of the stations
given above and upon a great number of isolated observations made during our travels,
also beyond the limit of permanent habitation, and at elevations so considerable that
they are approximatively comparable to the temperature in the free atmosphere.1
Amongst the results which I obtained from a chaotic mass of calculations, the
following may be mentioned as the principal features: —
The rate of decrease varies little as long as the same local forms prevail, but it
becomes at once more rapid when we approach the heights where a somewhat
sudden decrease of solid mass takes place, viz. where the ridges and peaks begin to
predominate.2 In the Alps this may be roughly estimated to be the case at about
6,000 to 7,000 feet in height; in the Himalaya it is at about 17,000; in both
regions it coincides, not quite accidentally, with the limit of trees.3 In Tibet the
1 In order better to define the decrease also at places for which I had but a limited number of observations,
such reductions were made as I have alluded to p. 112, Note 1. In referring these values to periods of longer
duration'care has chiefly to be taken that two stations thus compared are not very distant, and — what is not less
important—that they belong to the same type of climate.
2 What I allude to here may best be illustrated by the following analogous consideration. Suppose we had a
plastic model of the country cut through horizontally into sections of equal height or thickness; the succession of
those two sections which show the greatest difference coincides with the region where the decrease of solid mass is
most rapid.
3 This participation of a topographical element also explains why the limit of trees does not so completely
coincide with the same isothermal line throughout, even if we compare regions not very distant.
Materials. Tables for the yeaY and the seasons.
The calculation of the isothermal tables is based upon the means of the stations
given above and upon a great number of isolated observations made during our travels,
also beyond the limit of permanent habitation, and at elevations so considerable that
they are approximatively comparable to the temperature in the free atmosphere.1
Amongst the results which I obtained from a chaotic mass of calculations, the
following may be mentioned as the principal features: —
The rate of decrease varies little as long as the same local forms prevail, but it
becomes at once more rapid when we approach the heights where a somewhat
sudden decrease of solid mass takes place, viz. where the ridges and peaks begin to
predominate.2 In the Alps this may be roughly estimated to be the case at about
6,000 to 7,000 feet in height; in the Himalaya it is at about 17,000; in both
regions it coincides, not quite accidentally, with the limit of trees.3 In Tibet the
1 In order better to define the decrease also at places for which I had but a limited number of observations,
such reductions were made as I have alluded to p. 112, Note 1. In referring these values to periods of longer
duration'care has chiefly to be taken that two stations thus compared are not very distant, and — what is not less
important—that they belong to the same type of climate.
2 What I allude to here may best be illustrated by the following analogous consideration. Suppose we had a
plastic model of the country cut through horizontally into sections of equal height or thickness; the succession of
those two sections which show the greatest difference coincides with the region where the decrease of solid mass is
most rapid.
3 This participation of a topographical element also explains why the limit of trees does not so completely
coincide with the same isothermal line throughout, even if we compare regions not very distant.