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
The Tidal Waves The Tidal Waves The Tidal Waves were an American garage rock band formed in Roseville, Michigan, in 1964. Despite the young ages of the group members, the Tidal Waves were one of the more accomplished musical acts in the bustling Michigan garage band scene. They are best remembered for their regional hit, a cover version of "Farmer John", which managed to reach the Top 10 of several radio station charts around Detroit. Inspired by the Beatles' momentous appearance on "The Ed Sullivan Show" in February 1964, high school students Tom Wearing (drums, vocals), Mark Karpinski (lead guitar, vocals), and Vic