Atmosphere of Earth surface. The refractive index of air depends on temperature, giving rise to refraction effects when the temperature gradient is large. An example of such effects is the mirage. "Atmospheric circulation" is the large-scale movement of air through the troposphere, and the means (with ocean circulation) by which heat is distributed around Earth. The large-scale structure of the atmospheric circulation varies from year to year, but the basic structure remains fairly constant because it is determined by Earth's rotation rate and the difference in solar radiation between the equator and poles. The first atmosphere consisted of gases in the solar nebula,
Salt of the Earth (song) Jagger and Richards using a personal tape recorder, "Salt of the Earth" was recorded at London's Olympic Sound Studios in May 1968. Featuring on the song are the Los Angeles Watts Street Gospel Choir and a piano performance by Nicky Hopkins. These additions, and their prominence near the end of the song, are further developed on their next album "Let It Bleed"'s closing song, "You Can't Always Get What You Want". "Salt of the Earth" has a unique live history. It has only been played once to an instrumental playback and live five times. Salt of the Earth (song) "Salt