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
Where We Are Tour: Live from the O2 ‘What About Now’ video. In addition, the Blu-ray will feature a full hour and a half exclusive commentary where the boys discuss the show in detail and talk about what we can expect from the next tour. It is simply essential viewing for any Westlife fan. Where We Are Tour: Live from the O2 Where We Are Tour: Live from the O2 is a concert DVD by Irish boy band Westlife from their Where We Are Tour. During the group's Where We Are Tour, it was confirmed that their May 14 concert at the O2 Arena, London, England was recorded.