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
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.