Aspen-Pitkin County Airport Greenhouse Gas Emissions Inventory ...

mixing of pollutants in the atmosphere; a long lifetime will allow the pollutant to mix throughout theatmosphere. Average lifetimes can vary from about a week (e.g., sulfate aerosols) to more than a century(e.g., CFCs, carbon dioxide).LIGHT-DUTY VEHICLES: Automobiles and light trucks combined.LIQUEFIED NATURAL GAS (LNG): Natural gas converted to liquid form by cooling to a very lowtemperature.LIQUEFIED PETROLEUM GAS (LPG): Ethane, ethylene, propane, propylene, normal butane,butylene, and isobutane produced at refineries or natural gas processing plants, including plants thatfractionate new natural gas plant liquids.LONGWAVE RADIATION: The radiation emitted in the spectral wavelength greater than 4micrometers corresponding to the radiation emitted from the Earth and atmosphere. It is sometimesreferred to as terrestrial radiation or infrared radiation, although somewhat imprecisely.LOW EMISSION VEHICLE (LEV): A vehicle meeting the low-emission vehicle standards.METHANE (CH 4 ): A hydrocarbon that is a greenhouse gas with a global warming potential mostrecently estimated at 21. Methane is produced through anaerobic (without oxygen) decomposition ofwaste in landfills, animal digestion, decomposition of animal wastes, production and distribution ofnatural gas and petroleum, coal production, and incomplete fossil fuel combustion. The atmosphericconcentration of methane has been shown to be increasing at a rate of about 0.6 percent per year and theconcentration of about 1.7 per million by volume (ppmv) is more than twice its pre-industrial value.However, the rate of increase of methane in the atmosphere may be stabilizing.METHANOL (CH 3 OH): A colorless, poisonous liquid with essentially no odor and little taste. It is thesimplest alcohol with a boiling point of 64.7 degrees Celsius. In transportation, methanol is used as avehicle fuel by itself (M100), or blended with gasoline (M85).METRIC TON: Common international measurement for the quantity of greenhouse gas emissions. Ametric ton is equal to 1,000 kilograms, 2,204.6 pounds, or 1.1023 short tons.MIXING HEIGHT: The height of the completely mixed portion of atmosphere that begins at the earth’ssurface and extends to a few thousand feet overhead where the atmosphere becomes fairly stable. See also“inversion”.MOBILE SOURCE: A moving vehicle that emits pollutants. Such sources include airplanes, cars, trucksand ground support equipment.MONTREAL PROTOCOL ON SUBSTANCES THAT DEPLETE THE OZONE LAYER: TheMontreal Protocol and its amendments control the phase-out of ozone depleting substances productionand use. Under the Protocol, several international organizations report on the science of ozone depletion,implement projects to help move away from ozone depleting substances, and provide a forum for policydiscussions. In the United States, the Protocol is implemented under the rubric of the Clean Air ActAmendments of 1990.MOTOR GASOLINE: A complex mixture of relatively volatile hydrocarbons, with or without smallquantities of additives, obtained by blending appropriate refinery streams to form a fuel suitable for use inspark-ignition engines. Motor gasoline includes both leaded and unleaded grades of finished gasoline,blending components, and gasohol.A-8 4/3/2008