Calculates the range (i.e. slant range) given a distance measured along the earth's surface (i.e. down range) and beam elevation.
beam_range(distance, elev, k = 4/3, lat = 35, re = 6378, rp = 6357)
numeric. Distance from the radar as measured along sea level (down range) in m.
numeric. Beam elevation in degrees.
Standard refraction coefficient.
Geodetic latitude of the radar in degrees.
Earth equatorial radius in km.
Earth polar radius in km.
numeric. Beam range (slant range) in m.
depends on beam_height to calculate beam height.
# slant range of the 5 degree elevation beam at a down range of 100 km: beam_range(100000, 5) #>  100508.1