1. See upright. 1. horizontal. 1  being in a position or direction perpendicular to the plane of the horizon; upright; plumb. 2  of, pertaining to, or situated at the vertex. 3  Anatomyof or pertaining to the cranial vertex.
Last Updated: Radio wave, wave from the portion of the electromagnetic spectrum at lower frequencies than microwaves. The wavelengths of radio waves range from thousands of metres to 30 cm. These correspond to frequencies as low as 3 Hz and as high as 1 gigahertz (109 Hz).
To calculate the wavelength of a radio wave, you will be using the equation: Speed of a wave = wavelength X frequency. Since radio waves are electromagnetic waves and travel at 2.997 X 10^8 meters/second, then you will need to know the frequency of the radio wave. If the radio wave is on an FM station, these are in Megahertz.