METEOROLOGY — THEORY 215 
that and 
em AWD = ¢—ah/273. ¢ 4 ahi/(273)* — ¢—ah/273 is aFt 
ahi <= (ra) 
(273)? Equation (19) is evaluated in Table 10. 
(20) 
+ € —ah/273 (17) 
Hence Equation (20) is a small correction which must be 
(n= 1108S F — ub hAu ! (18) taken into account when ¢, the average temperature, 
100 differs appreciably from zero. Since this term con- 
where tributes only 1 per cent to the refractive index in the 
u = F(1 — €~ah273) | (19) extreme case of h = 500 m, ¢ = 40, it is sufficient to 
TABLE 8B. F(l, w) for ¢ froin 15 C (59 F) to 40 C (104 F); w from 12 to 24. 
w w Va 
ic 12 13 14 15 16 17 18 19 20 21 22 23 24 Lo Yr 
15 
16 
17 
18 
19 
20 
21 377.9 
22 376.2 
23 374.6 
24 372.9 
25 371.3 
26 369.7 
2 368.1 
28 366.7 
29 365.0 
30 363.4 
31 362.0 
32 360.4 
33 359.0 
34 357.4 
35 355.9 
36 354.4 
37 352.9 
38 351.5 
39 350.1 
40 348.6 
TaBLE 8C. F(t, w) for ¢ from 27 C (80.6 F) to 40 C (104 F); w from 24 to 36. 
N Ww wy “ie 
tc 24 25 26 27 28 29 30 31 32 33 34 35 36 / tF 
27 
28 
29 
30 
31 
32 
33 
34 
35 
36 
37 
38 
39 
40 
TaBLE 8D. F(t, w) for t from 34 C (93.2 F) to 40 C (104 F); w from 36 to 45. 
w w Wa 
tC\ 36 37 38 39 40 4l 42 43 44 45 Va tF 
34 
35 
36 
37 
38 
39 
