표 1. | Table 1. 전파 굴절도 및 대기 상태 | Refractive gradients and conditions.

Atmosphere condition	N-gradient	Atmosphere condition	N-gradient
Duct (trapping)	<−157 N/km	Normal	−79～0 N/km
Super	−157～−79 N/km	Sub	> 0 N/km
Standard	−39 N/km