| Webster's Online Dictionary |
| Expressions | Domain | Definition | |
| Earth's radius | Geography | The radius of a hypothetical earth for which the distance to the radio horizon, assuming rectilinear propagation (propagation in a geometric straight line), is the same as that for the actual earth with an assumed uniform vertical gradient of refractive index. Source: European Union. (references) | |
| Effective Earth's radius | Geography | The radius of an ideal spherical Earth without atmosphere for which propagation paths are along straight lines, the height and ground distances being the same as for the actual Earth in an atmosphere with a constant vertical gradient of refractivity. Source: European Union. (references) | |
Source: compiled by the editor from various references; see credits. | Top | ||
