XIX
A GRAPHICAL METHOD OF DETERMINING THE
ADIABATIC CHANGES OF MOIST AIR
(Meteorologische Zeitschrift, 1, pp. 421-431, 1884.)
(With diagram at end of book.)
IN the course of theoretical discussions meteorologists fre-
quently have to consider the changes of state which take place
in moist air when it is compressed or expanded without any
supply of heat. They wish to obtain solutions of such
problems as quickly as possible, and do not care to be referred
to complicated thermodynamic formulæ. In practice they
generally refer to the small but useful table published by
Prof. Hann in 1874.1 But it seems possible to attain greater
completeness, with at least equal facility, by using the graphical
method, and the accompanying table constitutes an attempt in
this direction. It contains nothing theoretically new except
in so far as it takes fully into account the peculiar behaviour of
moist air at 0°; this, to the best of my knowledge, has not been
treated of before. As the exact formulæ of the problem do
not seem to have been collected, I shall state them completely
under A. Under B I shall explain how the formulæ are
represented in the diagram. Under C I shall explain fully,
by means of a numerical example, the use of the diagram
(which may be purely mechanical). By following this example
1 Hann, Zeitschrift der österreichischen Gesellschaft für Meteorologie, 9,
p. 328, 1874.
2 The editor of the Met. Zeitschr. gives a reference to Guldberg and Mohn,
Etudes sur les mouvements de l'atmosphère, 1, pp. 9-16, and Österr. Zeitschrift,
1878, pp. 117-122. See also the supplementary note on p. 311 of this volume.