Atmosphere of Earth relatively warm air above a colder one), and in others by a zone which is isothermal with height. Although variations do occur, the temperature usually declines with increasing altitude in the troposphere because the troposphere is mostly heated through energy transfer from the surface. Thus, the lowest part of the troposphere (i.e. Earth's surface) is typically the warmest section of the troposphere. This promotes vertical mixing (hence, the origin of its name in the Greek word τρόπος, "tropos", meaning "turn"). The troposphere contains roughly 80% of the mass of Earth's atmosphere. The troposphere is denser than all its overlying atmospheric
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