544 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 51 



— R, work done by frictional forces or + R tlie kinetic 

 energy lost by the whole system through friction. 

 R^., R y , R z . the corresponding rectilinear components. 



Q, quantity of heat added to unit mass of air per unit time. 

 S, entropy of the unit mass of air. 

 (Q), quantity of heat added to the whole closed system in 

 whole time. 

 V, the average velocity of motion throughout any closed 



system for the whole time. 

 K, kinetic energy of the whole mass of air in the system. 

 (IK, increase of kinetic energy of the system. 

 T, potential temperature of air whose actual temperature 



is T at pressure p. 

 P, potential energy of the system due to its position and 

 the action of gravity. 

 r?P, change in potential energy of the system accompanying 

 the increase of kinetic energy, dK- 

 I, internal energy of the system. 

 dl, change of internal energy of the system when pressural 



forces do external work. 

 <5A, the work done by pressural forces. 



For the notation and values of these quantities in moist air see 

 Chapter IV later. 



Chapter I 



THE EQUATIONS OF ENERGY OF A MOVING PARTICLE AND OF THE 

 WHOLE MASS OF AIR IN A CLOSED SYSTEM 



§(10) One of the equations that holds good for the motion of the 

 air relative to the system of coordinates rotating with the earth is 



du dW 1 dp — 



dt dx ft dx x x 



and the other two are analogous. From these three there results as 

 the equation of energy of a definite particle of air of unit mass mov- 

 ing with the velocity c, 



d I ? \ 1 (dp dp\ - - 



TAa +w ) +■;{*-*) - Rccos (R ' C) " =0 - ■ (I) 



