The global atmosphere is roughly 78 percent nitrogen,21 percent oxygen,1 percent argon, and other trace gases (see inside the back cover). Those ratios changes very little with place or time in most of the atmosphere. The moisture content of the atmosphere, either as water vapor or as liquid drops or ice crystals, changes significantly with place and time and is responsible for many of the exciting, beautiful, and destructive things the atmosphere does.A typical water content. The water content of the atmosphere, at saturation, increasing temperature.