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 the music video of "What About Now". According to description released:‘The Where We Are Tour: Live From The 02’ also gives fans a rare, intimate glimpse into the lives of Nicky Byrne, Kian Egan, Mark Feehily and Shane Filan with the bonus ‘Where We Are – The Documentary’. This compelling behind the scenes documentary provides a fly on the wall insight into the lives of the band in the run up and during the tour. The boys also chat exclusively about why this tour meant so much to them. Both the DVD and Blu-ray versions will also include the epic