IDEAL STATES OF EQUILIBRIUM IN THE ATMOSPHERE. 



55 



Passing to the case of negative temperature gradients, ?'. e., of increase of 

 temperature upward, the height of the atmosphere remains infinite, the limit 

 determined by formula (a), section 43, having only the analytical meaning of the 

 limit of an imaginary continuation of the atmosphere below sea-level. This increase 

 of temperature with the height is meaningless if it be extended to the whole 

 atmosphere. 



But " temperature inversion " is well known as a local phenomenon, limited 

 to more or less narrow sheets, occurring specially often in the case of high pressure 

 during winter. The main feature of this state from a dynamic point of view is a 

 pronounced stability which can be overcome only by causes producing different 

 distribution of temperature. Values of Ry as \ or 1 give very simple forms 

 tor equations (a) and (b) and represent increases of temperature with the height 

 which may occur in the sheets of inversion, namely, 1.74 and 3.48 C. for every 

 100 meters of height. 



47. Numerical Representation of the States of Equilibrium. For the numer- 

 ical representation of any definite state of equilibrium we have the choice between 

 either of two methods. 



Tablk E. Ideal States of Atmospheric Equilibrium. Argument, Pressure. 



We can use the pressure as argument and register temperature, specific volume, 

 and height for suitable integer values of pressure. This method is used in table 

 E, giving temperature, specific volume, and height for each of the standard isobaric 

 surfaces. The four sections of the table correspond to four different temperature 

 gradients: (1) that giving homogeneous atmosphere; (2) that giving adiabatic equi- 

 librium in a perfectly dry atmosphere: (3) the gradient 0.0005 roughly representing 

 in the lower strata adiabatic equilibrium of saturated air and in the higher strata 

 stable equilibrium; (4) the gradient zero giving isothermic atmosphere. In all 

 these cases the temperature is supposed to be zero centigrade at sea-level, and the 

 height is measured in dynamic meters. 



