C1 revision

C1 revision

The atmosphere (air) that surrounds the Earth is made up mainly of nitrogen, oxygen CO2 and Argon
the relative proportions of the main gases in the atmosphere are approximately 78% nitrogen, 21% oxygen and 1% argon
other gases or particulates may be released into the atmosphere by human activity or by natural processes (eg volcanoes), and that these can affect air quality
the Earth’s early atmosphere was probably formed by volcanic activity and consisted mainly of carbon dioxide and water vapour
water vapour condensed to form the oceans when the Earth cooled
the evolution of photosynthesising organisms added oxygen to, and removed carbon dioxide from, the atmosphere.
carbon dioxide was removed from the atmosphere by dissolving in the oceans and then forming sedimentary rocks, and by the formation of fossil fuels
human activity has changed the composition of the atmosphere by adding a small amounts of carbon monoxide, nitrogen oxides and sulfur dioxide to the atmosphere and extra carbon dioxide and small particles of solids (eg carbon) to the atmosphere
some of these substances, called pollutants, are directly harmful to humans reduces the amount of oxygen that blood can carry), and that some are harmful to the environment and so cause harm to humans indirectly (eg sulfur dioxide causes acid rain).
By Benita Odeyemi

Resource summary

	Created by benita odeyemi about 9 years ago