R: Distance to the horizon

horizon {geosphere} | R Documentation

## 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

http://williams.best.vwh.net/avform.htm#Horizon

Bowditch, 1995. American Practical Navigator. Table 12.

### Examples

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

[Package geosphere version 1.5-5 Index]