If the atmosphere is clear where the rays of light are tangential to the surface the refraction would raise the apparent altitude of the Moon or star above the limb by 1 .1, i.e. double the standard value of refraction for an observer on the Earth's surface at sea level observing an object on the horizon.
(the atmosphere; is; clear) (the refraction; would raise; the apparent altitude of the Moon or star above the limb) (an observer on the Earth's surface at sea level; observing; an object; T:on the horizon)
the atmosphere the refraction an observer on the Earth's surface at sea level
is would raise observing
clear
the apparent altitude of the Moon or star above the limb
an object T:on the horizon