zenith - n. 천정; 정상, 절정, 극치

• nadir

• Daily variations in reflectance factors were quantified in relation to changes in the solar zenith angle, applying the modified Walthall et al.
• The problem is that the range distance to the sodium beacon constantly changes with weather and telescope zenith angle.
• The time of Zuhr, the midday prayer, begins after the sun has crossed the zenith point and has begun to decline.