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
What We Live For made available the same day. The album's opening two tracks, "What We Live For" and "I'm Born to Run" were also made available to purchase in April 2016, on the album's page on iTunes. Supporting the album, the band embarked on a 19-date tour of the United States from March through to May 2015, performing songs appearing on the new album live, in the lead-up to its release. It was announced through the band's Facebook page that the album's release date was pushed nearly two months from their original date, saying they are "putting the finishing touches" on their album