Atmosphere of Earth (see the temperature section, below). Because the general pattern of the temperature/altitude profile is constant and measurable by means of instrumented balloon soundings, the temperature behavior provides a useful metric to distinguish atmospheric layers. In this way, Earth's atmosphere can be divided (called atmospheric stratification) into five main layers. Excluding the exosphere, the atmosphere has four primary layers, which are the troposphere, stratosphere, mesosphere, and thermosphere. From highest to lowest, the five main layers are: The exosphere is the outermost layer of Earth's atmosphere (i.e. the upper limit of the atmosphere). It extends from the exobase, which is located at
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