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
Vienna Convention for the Protection of the Ozone Layer layer. One of the outcomes of the Vienna Convention was the creation of a panel of governmental atmospheric experts known as the Meeting of Ozone Research Managers, which assesses ozone depletion and climate change research and produces a report for the Conference of Parties (COP). Additionally, the COP utilizes the data assessed to suggest new policies aimed at limiting CFC emissions. Currently, the COP meets every three years and coordinates with the timing of a similar meeting rendered under the Montreal Protocol. The Ozone Secretariat functions as an administrator of the COP, Montreal Meeting of Parties (MOP), and Open-Ended Working