Calculates the distance as measured over the earth's surface (the down range) for a given beam elevation and slant range.

beam_distance(range, elev, k = 4/3, lat = 35, re = 6378, rp = 6357)

## Arguments

range

numeric. Slant range in m, the length of the skywave path between target and the radar antenna.

elev

numeric. Beam elevation in degrees.

k

Standard refraction coefficient.

lat

Geodetic latitude of the radar in degrees.

re

rp

## Value

numeric. Beam distance (down range) in m.

## Details

depends on beam_height to calculate beam height.

## Examples

# down range of the 5 degree elevation beam at a slant range of 100 km:
beam_distance(100000, 5)
#> [1] 99495.13