For a given zenith angle, the scattered light contribution comes from well defined layer of atmosphere, which can be termed as an effective scattering height.

The air mass then is simply the secant of the zenith angle :

At a zenith angle of 60 , the air mass is approximately 2.

This gives usable results up to approximately 80 , but the accuracy degrades rapidly at greater zenith angles.

When the observer is at an elevation greater than that of the horizon, the zenith angle can be greater than 90 .

The tilt angle, or zenith angle, is generally 15 to 30 degrees, and the horizontal beams are typically oriented at right angles to one another.

For scientists, the zenith is the direction of reference for measuring the zenith angle.

The zenith angle is the angle between a place in the sky (usually a star) and the local zenith.

The Leighton relationship above shows how production of ozone is directly related to the solar intensity and hence to the zenith angle.

The zenith angle, usually represented as φ, is the offset from the line collinear with the z-axis in the positive direction.