elevation noun [C/U]. âº âheight above the âsurface of the âearth, or an âarea that is âhigher than the âsurrounding âland: [C] At âhigher elevations, the âair is âcolder. (Definition of elevation from the Cambridge Academic Content Dictionary Â© Cambridge University Press).
A dissolved gas is, simply enough, gas that has been dissolved into another material. This creates a solution, a mixture, where the gas is the solute, the minor component, and the other material, generally a liquid, is the solvent, the main component.
Natural gas is a mixture of flammable gases, mainly the hydrocarbons methane and ethane, that occurs beneath the surface of the Earth. Helium is also found in relatively high concentrations in natural gas. Manufactured gas is derived principally from coal and petroleum.