ARTICLE II. 



ON THE CONSTRUCTION OF ISOBARIC CHARTS FOR HIGH LEVELS IN THE 

 EARTH'S ATMOSPHERE AND THEIR DYNAMIC SIGNIFICANCE. 



(Plate VIII.) 



BY J. \y. Sandstrom, Stockholm, Sweden. 



(Read April 14, 1905.) 



I. Introduction. 



The construction of isobaric charts for high levels has been attempted by several 

 investigators in dynamic meteorology. I will here only mention : 



(rt) Teisserenc de Bort's attempt to draw such charts over the whole earth based 

 on the isobars and isotherms at sealevel, the observed direction of motion of the 

 clouds, and an assumed probable diminution of temperature with altitude ; 



(b) Koeppen's graphic presentation of such charts based on the isobars and iso- 

 terms at sealevel, and 



(c) Hergesell's construction of similar charts on the basis of the results of the 

 international balloon ascensions. 



From the relation of the isobaric charts for sealevel to the dynamics of the lower 

 atmospheric strata, the analogous relation of the isobaric charts for higher levels to 

 the dynamics of the uj^per strata has been correctly appreciated. Indeed from the 

 charts already drawn we have succeeded in explaining many of the phenomena of the 

 upper layers of the atmosphere, for example, the general circulation from West to 

 East * and the movements of the clouds in the upper portions of cyclones.f 



My attempts to apply Bjerknes' theory of solenoids J to dynamic meteorology 

 have led me also to the construction of isobaric charts for higher levels. This theory 

 requires, however, that such charts be drawn on level surfaces of gravity and not on 

 surfaces of equal elevation above sealevel. In the following pages I shall show how 

 such charts can be constructed from meteorological observations obtained by means of 

 kites and balloons in the free air. 



*L. Teisserenc de Bort : Etade snr la circulation generate de I'atmosphere. Annales du Bnrean Central Meteorolo- 

 giqne de France, 1885, Tome 4. 



t W. Koeppen : Ueber die Gestalt der Isobaren in ihrer Abbangnng von SeehiJbe u. Temperaturvertheilang. Met. 

 Zeit., 1888, p. 476. 



tSee Bjerknes, in Monthly Weather Review, 1900, October, pp. 434-443, December, pp. 532-535. Sandstrom : On 

 the Application of Prof. V. Bjerknes' Theory, in Memoirs Royal Swedish Academy, 1900, vol. 33. 



A. p. S.— XXI. A. 21, 11, '05 



