<P> The three major constituents of air , and therefore of Earth 's atmosphere , are nitrogen , oxygen , and argon . Water vapor accounts for roughly 0.25 % of the atmosphere by mass . The concentration of water vapor ( a greenhouse gas ) varies significantly from around 10 ppm by volume in the coldest portions of the atmosphere to as much as 5 % by volume in hot , humid air masses , and concentrations of other atmospheric gases are typically quoted in terms of dry air ( without water vapor ) . The remaining gases are often referred to as trace gases , among which are the greenhouse gases , principally carbon dioxide , methane , nitrous oxide , and ozone . Filtered air includes trace amounts of many other chemical compounds . Many substances of natural origin may be present in locally and seasonally variable small amounts as aerosols in an unfiltered air sample , including dust of mineral and organic composition , pollen and spores , sea spray , and volcanic ash . Various industrial pollutants also may be present as gases or aerosols , such as chlorine ( elemental or in compounds ) , fluorine compounds and elemental mercury vapor . Sulfur compounds such as hydrogen sulfide and sulfur dioxide ( SO ) may be derived from natural sources or from industrial air pollution . </P>
<P> The three major constituents of air , and therefore of Earth 's atmosphere , are nitrogen , oxygen , and argon . Water vapor accounts for roughly 0.25 % of the atmosphere by mass . The concentration of water vapor ( a greenhouse gas ) varies significantly from around 10 ppm by volume in the coldest portions of the atmosphere to as much as 5 % by volume in hot , humid air masses , and concentrations of other atmospheric gases are typically quoted in terms of dry air ( without water vapor ) . The remaining gases are often referred to as trace gases , among which are the greenhouse gases , principally carbon dioxide , methane , nitrous oxide , and ozone . Filtered air includes trace amounts of many other chemical compounds . Many substances of natural origin may be present in locally and seasonally variable small amounts as aerosols in an unfiltered air sample , including dust of mineral and organic composition , pollen and spores , sea spray , and volcanic ash . Various industrial pollutants also may be present as gases or aerosols , such as chlorine ( elemental or in compounds ) , fluorine compounds and elemental mercury vapor . Sulfur compounds such as hydrogen sulfide and sulfur dioxide ( SO ) may be derived from natural sources or from industrial air pollution . </P>
what are the three main parts of the atmosphere
what are the three main parts of the atmosphere
nitrogen oxygen argon
nitrogen oxygen argon