The Probert Encyclopaedia of General Information

ALTITUDE

In mathematics, altitude is the perpendicular height of the vertex or apex of a plane figure or solid above the base.

In astronomy it is the vertical height of any point or body above the horizon. It is measured or estimated by the angle subtended between the object and the plane of the horizon, and may be either true or apparent. The apparent altitude is that which is obtained immediately from observation; the true altitude, that which results from correcting the apparent altitude, by making allowance for parallax, refraction, etc.
Research Altitude