surface wave
Ground waves are electromagnetic waves that follow the curvature of the earth during wave propagation and propagate near the ground. Because of their propagation they are called ground wave propagation.
Ground waves propagate hemispherically in all directions. Ground waves are partially absorbed by the earth's surface and can therefore propagate over certain distances, which depend largely on the frequency and the transmitting power. The higher the frequency, the shorter the range of ground waves.
Ground waves occur in the long-wave range and, to a lesser extent, in the medium-wave range. Their propagation can be 1,000 km or more. As the frequency increases, the losses at the earth's surface increase and reduce the propagation, which can be about 300 km in the medium-wave range and less than 100 km in the short-wave range. Ground waves were and are used primarily in marine radio for communication between marine radio stations and coastal stations.