dip of the horizon نشیب ِ افق našib-e ofoq
*Fr.: inclinaison de l'horizon*
The angle created by the observer's line of sight to the
→ *apparent horizon* and t
he → *true horizon*.
Neglecting the → *atmospheric refraction*, dip of the horizon
can be expressed by θ (radians) = (2*h*/*R*)^{1/2}, where
*h* is the observer's height and *R* the Earth's radius. An an example,
for a height of 1.5m above the sea, and *R* = 6.4 x 10^{6} m,
the dip angle
is about 0.00068 radians, or 0.039 degrees, about 2.3 minutes of arc, quite
appreciable by the eye. See also → *distance to the horizon*.
Same as → *dip angle*. → *dip*; → *horizon*. |