horizon {geosphere}

Distance to the horizon

Description

Empirical function to compute the distance to the horizon from a given altitude. The earth is assumed to be smooth, i.e. mountains and other obstacles are ignored.

Usage

horizon(h, r=6378137)

Arguments

h

altitude, numeric >= 0. Should have the same unit as r

r

radius of the earth; default value is 6378137 m

Value

Distance in units of h (default is meters)

Author(s)

Robert J. Hijmans

References

https://www.edwilliams.org/avform147.htm#Horizon

Bowditch, 1995. American Practical Navigator. Table 12.

Examples

horizon(1.80) # me
horizon(324)  # Eiffel tower