DOI Seite / Zitierlink:
https://doi.org/10.11588/diglit.20140#0145
VII. NON-PERIODICAL VARIATIONS.
Reduction to and Comparison with trite Means. Very little correction required in the tropics. Constancy of the mean
total for the globe as far as our meteorological data go back. Modifications of non-periodical variations in
different seasons and latitudes.
Variability. Definition: total, absolute, mean variability. Numerical data for India and High Asia. Analysis, and
comparison with Europe.
Vestiges of permanent Alteration of our Climate, viz. within the present geological period. Drainage of the
Himalayan lakes; gradual exsiccation of those remaining in Tibet.
REDUCTION TO AND COMPARISON WITH TRUE MEANS.
The annual and monthly means in different years show alterations which make
a longer series of observations desirable in the tropics as well as everywhere, for
eliminating temporary irregular disturbances. In the northern temperate zone for
most parts of the globe the vicinity of neighbouring stations, allows one to calculate a
reduction to true means (for eliminating the "non-periodical" disturbances), a method
first introduced by Dove1 and applied to a great number of stations.
In the tropics, however, I found the materials not yet continued sufficiently
long for applying such considerations with sufficient accuracy, and, again, the irregular
modifications from year to year are altogether much smaller than in higher latitudes
—the more I had reason to exclude from the general mean such years of which I
had to doubt (as detailed at the respective stations) the proper combination of hours;
not a century corrects this if so continued, but one such year, if not excluded, can easily
conceal the correct result of several others, unless their number is very great already.
1 Dove, Abhandl. der Berlin. Acad., 1838, pp.265—415; 1839, pp. 305—440; 1842, pp. 117—241; 1845, pp. 141-320
1852, pp. 85—328; 1856, pp. 121—192; Supplement-Band II., 1855.
IV. 16
Reduction to and Comparison with trite Means. Very little correction required in the tropics. Constancy of the mean
total for the globe as far as our meteorological data go back. Modifications of non-periodical variations in
different seasons and latitudes.
Variability. Definition: total, absolute, mean variability. Numerical data for India and High Asia. Analysis, and
comparison with Europe.
Vestiges of permanent Alteration of our Climate, viz. within the present geological period. Drainage of the
Himalayan lakes; gradual exsiccation of those remaining in Tibet.
REDUCTION TO AND COMPARISON WITH TRUE MEANS.
The annual and monthly means in different years show alterations which make
a longer series of observations desirable in the tropics as well as everywhere, for
eliminating temporary irregular disturbances. In the northern temperate zone for
most parts of the globe the vicinity of neighbouring stations, allows one to calculate a
reduction to true means (for eliminating the "non-periodical" disturbances), a method
first introduced by Dove1 and applied to a great number of stations.
In the tropics, however, I found the materials not yet continued sufficiently
long for applying such considerations with sufficient accuracy, and, again, the irregular
modifications from year to year are altogether much smaller than in higher latitudes
—the more I had reason to exclude from the general mean such years of which I
had to doubt (as detailed at the respective stations) the proper combination of hours;
not a century corrects this if so continued, but one such year, if not excluded, can easily
conceal the correct result of several others, unless their number is very great already.
1 Dove, Abhandl. der Berlin. Acad., 1838, pp.265—415; 1839, pp. 305—440; 1842, pp. 117—241; 1845, pp. 141-320
1852, pp. 85—328; 1856, pp. 121—192; Supplement-Band II., 1855.
IV. 16