Atmosphere Atmosphere An atmosphere (from Modern Greek ἀτμός "(atmos)", meaning 'vapour', and σφαῖρα "(sphaira)", meaning 'sphere') is a layer or a set of layers of gases surrounding a planet or other material body, that is held in place by the gravity of that body. An atmosphere is more likely to be retained if the gravity it is subject to is high and the temperature of the atmosphere is low. The atmosphere of Earth is composed of nitrogen (about 78%), oxygen (about 21%), argon (about 0.9%) , carbon dioxide (0.03%) and other gases in trace amounts. Oxygen is used by most organisms
Gas meter prover Gas meter prover A gas meter prover is a device which verifies the accuracy of a gas meter. Provers are typically used in gas meter repair facilities, municipal gas meter shops, and public works shops. Provers work by passing a known volume of air through a meter while monitoring the gas meters register, index, or internal displacement. The prover then displays a proof, a value expressed as a percent which compares the volume of air passed with the volume of air measured to determine the meters accuracy. Since the early 1900s, bell provers have been the most common reference standard