Atmosphere of Earth However, polar stratospheric or nacreous clouds are occasionally seen in the lower part of this layer of the atmosphere where the air is coldest. The stratosphere is the highest layer that can be accessed by jet-powered aircraft. The troposphere is the lowest layer of Earth's atmosphere. It extends from Earth's surface to an average height of about , although this altitude varies from about at the geographic poles to at the Equator, with some variation due to weather. The troposphere is bounded above by the tropopause, a boundary marked in most places by a temperature inversion (i.e. a layer of
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