Changes

The [[atmosphere]] surrounding the [[Earth]] consists of a mixture of gases commonly called '''air'''. The most common gases are [[nitrogen]] (77%) and [[oxygen]] (about 22%). There are other gases as well, but in very small quantities. The air is important for almost all life on Earth including [[plant]]s and [[animal]]s. Plants need carbon dioxide for [[photosynthesis]]. Animals need to breathe air to get the oxygen they need to survive. As [[altitude]] increases, the concentration of air molecules in the atmosphere decreases. The air is thinner higher in the atmosphere because there is lower pressure higher up in the atmosphere.  

The [[atmosphere]] surrounding the [[Earth]] consists of a mixture of gases commonly called '''air'''. The most common gases are [[nitrogen]] (77%) and [[oxygen]] (about 22%). There are other gases like [[Argon]] or [[Helium]] as well, but in very small quantities. The air is important for almost all life on Earth including [[plant]]s and [[animal]]s. Plants need carbon dioxide for [[photosynthesis]]. Animals need to breathe air to get the oxygen they need to survive. As [[altitude]] increases, the concentration of air molecules in the atmosphere decreases. The air is thinner higher in the atmosphere because there is lower pressure higher up in the atmosphere.  

There is a special layer of air molecules high in the [[stratosphere]] layer of Earth’s atmosphere, called the [[ozone layer]]. The composition of the atmosphere is different in the ozone layer. There are more [[ozone]] molecules than anywhere else. Ozone molecules help block some of the [[Sun]]’s strongest rays. Currently, [[scientist]]s are monitoring this layer. It has recently become so thin at the [[South Pole]] where the molecules are being destroyed that we call it a hole.  The hole in the ozone layer has led to the widespread ban on chemicals called CFCs.

There is a special layer of air molecules high in the [[stratosphere]] layer of Earth’s atmosphere, called the [[ozone layer]]. The composition of the atmosphere is different in the ozone layer. There are more [[ozone]] molecules than anywhere else. Ozone molecules help block some of the [[Sun]]’s strongest rays. Currently, [[scientist]]s are monitoring this layer. It has recently become so thin at the [[South Pole]] where the molecules are being destroyed that we call it a hole.  The hole in the ozone layer has led to the widespread ban on chemicals called CFCs.