Figure 5. Refracted horizontal angle (arcsecond/m) w.r.t zenith angle (°). (i.e., zenith angle smaller and larger than 90° corresponds to above and below horizon, respectively)

From

Improved Model of Refracted Horizontal Angle: Dependency on Zenith Angle

Mansoor Sabzali, Lloyd Pilgrim

American Journal of Civil Engineering and Architecture. 2023, 11(2), 38-44 doi:10.12691/ajcea-11-2-2