Coefficients of clear-day model

From Hottel

(a) Coefficients a0, a1, and k as a function of altitude A above sea level (in kilometers), for two levels of visibility

coefficient 23 km (14.3 mi) visibility 5 km (3.11 mi) visibility
a0 r0·[0.4237 - 0.00821 x (6.0 - A)2] r0·[0.2538 - 0.0063 x (6.0 - A)2]
a1 r1·[0.5055 + 0.00595 x (6.5 - A)2] r1·[0.7678 + 0.0010 x (6.5 - A)2]
k rk·[0.2711 + 0.01858 x (2.5 - A)2] rk·[0.2490 + 0.0810 x (2.5 - A)2]

 

 
 
 

(b) Correction factors r0, r1, and rk

Climate type r0 r1 rk
Visibility
23 km 5 km
Tropical 0.95 0.92 0.98 1.02
Midlatitude summer 0.97 0.96 0.99 1.02
Subarctic summer 0.99 0.98 0.99 1.01
Midlatitude winter 1.03 1.04 1.01 1.00