Wind

Wind — air in motion — is a vital ecological factor in its own right, and its composition mirrors that of the atmosphere as a whole: roughly 78% nitrogen, 21% oxygen, 0.03% carbon dioxide, and 0.93% argon and other gases, along with water vapour, dust, pollutants, spores and pollen carried along with it. Wind speed is measured with an anemometer. Wind's ecological effects are a genuine mixed bag. On the helpful side, it plays a role in forming rain, drives wave action in lakes and oceans (which aerates the water), increases the rate of transpiration, carries pollen for wind-pollinated (anemophilous) plants, and disperses many fruits, seeds and spores far from the parent plant. On the harmful side, strong wind causes soil erosion and reduces soil fertility, can uproot large trees outright, and — when it blows persistently from one direction — trains trees into a lopsided 'flag form' as growth is suppressed on the windward side. At a larger, atmospheric scale, gases released into the air (from industry, vehicles, forest fires, sulphur dioxide and dimethyl sulphur) drive climatic change; fine aerosol particles reflect incoming solar radiation …