|Neon||Ne||18.20 parts per million|
|Helium||He||5.20 parts per million|
|Krypton||Kr||1.10 parts per million|
|Sulfur dioxide||SO2||1.00 parts per million|
|Methane||CH4||2.00 parts per million|
|Hydrogen||H2||0.50 parts per million|
|Nitrous Oxide||N2O||0.50 parts per million|
|Xenon||Xe||0.09 parts per million|
|Ozone||O3||0.07 parts per million|
|Nitrogen dioxide||NO2||0.02 parts per million|
|Iodine||I2||0.01 parts per million|
The atmosphere is a cloud of gas and suspended solids extending from the Earth's surface out many thousands of miles, becoming increasingly thinner with distance but always held by the Earth's gravitational pull.
The atmosphere is made up of layers surrounding the earth that holds the air we breath, protects us from outer space, and holds moisture (clouds), gases, and tiny particles. In short, the atmosphere is the protective bubble we live in.
This protective bubble consists of several gases (below) with the top four making up 99.998% of all gases. By far, the most common, nitrogen, dilutes oxygen and prevents rapid burning at the earth's surface. Living things need it to make proteins. Oxygen is used by all living things and is essential for respiration.
It is also necessary for combustion or burning. Argon is used in light bulbs. Plants use carbon dioxide to make oxygen. Carbon dioxide also acts as a blanket and prevents the escape of heat into outer space.