In practice the apparent horizon has a negative altitude, whose absolute value gets larger as the observer ascends higher above sea level, due to the curvature of the Earth.
From the en.wikipedia.org
The high-tech horizon was also apparent to Lackey, who worked as a technology consultant.
From the newsobserver.com
Plenty of people did so, just by observing the apparent behaviour of objects on the horizon.
From the guardian.co.uk
On the horizon, refraction is slightly greater than the apparent diameter of the Sun.
From the en.wikipedia.org
There's no sign on the horizon of U2's heir apparent.
From the usatoday.com
This is true because at low latitudes the sun's apparent movement is perpendicular to the observer's horizon.
From the en.wikipedia.org
A more exact mathematical description distinguishes several kinds of horizon, notably event horizons and apparent horizons cf.
From the en.wikipedia.org
We have seen no real plan, no strong leadership, no apparent willingness to confront the growing danger on the horizon.