68 



DYNAMIC METEOROLOGY AND HYDROGRAPHY. 



it 



I 



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the observed pressures and once the observed heights, will give a valuable control, 



especially useful in correcting the records of the barometer. 



The common result of examples i and 2 is illustrated graphically by the three 



verticals of fig. 4, the principle of the representation being the same as that used 



previously in figs. 1 and 2. The first vertical, representing the equilibrium rela- 

 tion between dynamic height and pressure, may 

 be constructed from columns 5 and 8 or 1 1 and 

 18 of table J, or from the corresponding columns 

 6 and 9 or 12 and 18 of table K. The divisions 

 on the second vertical, representing the equilib- 

 rium relation between pressure and specific vol- 

 ume, are drawn according to the figures in col- 

 umns 5, 7, and 10 of table J, or the corresponding 

 columns 6, 8, and 11 of table K. The divisions 

 on the third vertical, giving the equilibrium rela- 

 tion between dynamic height and density, are 

 drawn in accordance with the figures contained 

 in columns 11 and 19 of table J, or 12 and 19 of 

 table K. To obtain greater accuracy the specific 

 volumes in column 10, table J, or column 11, 

 table K, have been changed into densities and 

 used to correct the divisions. 



We shall later make important practical ap- 

 plications of verticals as those of fig. 4, drawing 

 vertical sections as in figs. 13, 14, 21, 24 below. 

 The most important use will be made, however, ot 

 the numbers contained in columns 8 and 7 of 

 table J, respectively, 9 and 8 of table K, i. e., the 

 numbers giving the height of the standard isobaric 

 surfaces and the average specific volume of the 

 air between them, and the numbers contained in 

 columns 18 and 19 of both tables, i. e., the num- 

 bers giving the pressure in standard level surfaces 

 and the average density of the air between them. 

 From such numbers as these we shall draw syn- 

 optical charts such as those found in Chapter VII, 

 representing in two different ways the distribution 

 of pressure and of mass in the atmosphere. 



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5000- - 



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Fig. 



State of atmospheric equilibrium 

 above Berlin, July 31, 1901. 



Example i. Observed time, -pressure (m-dars), 

 temperature (C), humidity {per cent). (Table J.) 

 From the observed pressures and temperatures (columns 

 2 and 3) the curve of true temperatures is drawn (curve 

 to the left in fig. 5). By means of table 7 M the curve of virtual temperature for saturated air is 

 drawn (curve to the right). Using the percentages of humidity (column 4) the curve of virtual tem- 

 perature is drawn between the other two curves. (See section 23.) 



