ROSSBY DIAGRAM—INTERPRETATION 19 
Tr 100 90 80 70 60 5§0 40 30 20 
400 
600 
240 800 
ae 1000 
280 
300 
320 
Fic. 4. THE MILLAR NOMOGRAM FOR RAPID EVALUATION OF w AND 6, SHOWING 
MAIN DIVISIONS ONLY. 
DIRECTIONS: To obtain w, lay a ruler across the p and r scales, setting 
the edge on the pressure p, and the percent relative humidity r. Then, hold- 
ing the ruler rigid, hold a 90° set square against the ruler, and slide the square 
along until the edge is set at the temperature on the T scale. The correspond- 
ing value of w will then be read against the square on the w scale. To obtain 
0, proceed in the same way, but setting on the p, w’, and T’ scales. For w’, 
use the value of w previously obtained. (For further details see Bull. Amer. 
Met. Soc., Oct. 1935, p. 229; or June-July, 1936, p. 18). 
