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 |