Radio atmospheric km. For ELF waves (< 3 kHz), ray theory becomes invalid, and only mode theory is appropriate. Here, the zeroth mode begins to dominate and is responsible for the second window at greater distances. Resonant waves of this zeroth mode can be excited in the Earth–ionosphere waveguide cavity, mainly by the continuing current components of lightning flowing between two return strokes. Their wavelengths are integral fractions of the Earth's circumference, and their resonance frequencies can thus be approximately determined by "f" ≃ "mc"/(2π"a") ≃ 7.5 "m" Hz (with "m" = 1, 2, ...; "a" the Earth's radius and "c" the
Radio Waves (Eli Young Band song) on the "Billboard" Hot Country Songs chart on the chart dated July 25, 2009. Radio Waves (Eli Young Band song) "Radio Waves" is a song recorded by American country music group Eli Young Band. It was released in June 2009 as the third single from the album "Jet Black & Jealous". The song reached number 35 on the "Billboard" Hot Country Songs chart. The song was written by Mike Eli and Blu Sanders. "Radio Waves" is an up-tempo song in which the male narrator is reflecting on a past relationship with regret. The narrator sings the song to former lover