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
Last Day on Earth (The Walking Dead) 10 in his review and commented, "For all that "Last Day on Earth" was really about, and what was important about it, it went on too long. And then failed to deliver a satisfying exclamation point. Instead, we got another fake out/cliffhanger. A technique this show is absolutely over indulging in. Jeffrey Dean Morgan was terrific as Negan though." Zack Handlen of "The A.V. Club" gave the episode a C, the lowest grade given by the website for the show to date, faulting the episode for awkward, drawn-out writing and forced story arcs which couldn't maintain an atmosphere of suspense