Atmosphere of Earth and balloons, and too low to permit orbital spacecraft. The mesosphere is mainly accessed by sounding rockets and rocket-powered aircraft. The stratosphere is the second-lowest layer of Earth's atmosphere. It lies above the troposphere and is separated from it by the tropopause. This layer extends from the top of the troposphere at roughly above Earth's surface to the stratopause at an altitude of about . The atmospheric pressure at the top of the stratosphere is roughly 1/1000 the pressure at sea level. It contains the ozone layer, which is the part of Earth's atmosphere that contains relatively high concentrations 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