Three-fourths of all air lives in the troposphere, the shortest layer that the earth atmosphere. Wait is a mixture that gases, most of i beg your pardon are normally occurring. Air likewise contains a far-reaching amount the human-made wait pollutants, including some that space not for sure to breathe and also some that warmth our planet’s climate. The troposphere also contains water in all three phases (liquid, solid, and also gas) as well as solid particles, called aerosols.

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The dry composition the the environment is mostly nitrogen and also oxygen. It likewise contains fractional quantities of argon and also carbon dioxide and trace amounts of other gases, such together helium, neon, methane, krypton, and also hydrogen (NASA). Credit:


The most abundant naturally emerging gas is Nitrogen (N2), which makes up around 78% the air. Oxygen (O2) is the second most abundant gas at about 21%. The inert gas Argon (Ar) is the third most abundant gas at .93%. There are also trace quantities of carbon dioxide (CO2), neon (Ne), helium (He), methane (CH4), krypton (Kr), hydrogen (H2), nitrous oxide (NO), xenon (Xe), ozone (O3), iodine (I2), carbon monoxide (CO), and ammonia (NH3) in the atmosphere.

Water Vapor

Due come the water cycle, the amount of water in the air is continually changing. The reduced troposphere have the right to contain up to 4% water vapor (H2O) in areas near the tropics, while the poles contain only trace amounts of water vapor. The concentration that water vapor decreases considerably with altitude. The upper troposphere has considerably less water vapor than air near the surface, the stratosphere and also mesosphere have nearly no water vapor, and the thermosphere consists of none in ~ all.


Air likewise contains tiny solid particles called aerosols, such together dust, sea salt, and also ash from erupting volcanoes or forest fires. Plenty of of these particles room so small that they space microscopic. Others are huge enough come see. Aerosols affect climate by helping clouds kind and shading the earth by scattering or absorbing sunlight. In the critical century, manufacturing and widespread use of burning engines have actually increased the number of aerosols in the atmosphere as particulate issue spews native smokestacks and also exhaust pipes. Burning wood and also other products also include particles to the air.

Atmospheric Chemistry

Like every little thing on Earth, the waiting is do of chemicals. The chemistry in the wait often combine with every other, or with other chemicals native the earth’s surface, with chemical reactions. Many of these chemical reactions assist maintain healthy and balanced natural environments and also are critical for plants and animals. Nitrogen gas in the atmosphere does nearly nothing, however nitrogen somewhere else on earth is crucial for life. With the nitrogen cycle, nitrogen makes its method into soil and water, binds with various other elements, and can be supplied by life things. Oxygen native the atmosphere reasons oxidation reactions that help break down matter and release nutrients right into soils, and is supplied by humans and animals in cellular respiration.

Atmospheric chemistry in the troposphere is also influenced by human-made chemicals that have the right to negatively influence human health and also the environment. Because that example:

Smog, i m sorry is greatly made the ozone and also particulate carbon (soot) emitted by coal-burning strength plants, reasons damage come the lung of humans and also animals. Factories that burn fossil fuels also release sulfur and nitrogen dioxides, which incorporate with water in the atmosphere to make acid rain. Acid rain reasons damage come natural and human-made environments.

Chemistry of the Air

The table listed below lists the significant gas components and also their role in the atmosphere. Click on each molecule name to learn more about them.

GasChemical & MolecularStructureRole in the atmosphere



78% that the air in the atmosphere is nitrogen. Nitrogen is transferred to plants, animals, and also the atmosphere through the nitrogen cycle.

Nitrogen Oxides


Nitrogen oxides are air pollutants that contribute to the formation of ozone. They additionally create nitric acid, i beg your pardon is part of mountain rain, when they mix with water droplets in the air.



Oxygen makes up 21% of the atmosphere. That is very reactive and also forms link with many other chemicals, and is essential for respiration in life things.



Ozone in the troposphere is a human-made pollutant. Ozone in the stratosphere forms the ozone layer, which is crucial for the survive of life in ~ the earth’s surface.



Argon renders up around 1% that the atmosphere and comes largely from the decay of potassium in the earth’s crust. The is an inert gas, which method that it does not react with various other chemicals.

Water Vapor


Water is cycled through every one of Earth’s solution in every of its 3 phases: solid, liquid, or gas. Water vapor in the atmosphere is a greenhouse gas because of its heat-trapping ability.

Carbon Dioxide

Carbon dioxide normally composes about .03% the the atmosphere, however the quantity is increasing as result of the burn of fossil fuels. Plants and eubacteria use carbon dioxide throughout photosynthesis. Humans, various other animals, and also plants include it to the air through respiration. Carbon dioxide is a heat-trapping greenhouse gas.

Carbon Monoxide


Carbon monoxide in the air originates from burning fuel in vehicles, volcanoes, and also forest fires. The is a poisonous gas.



Methane gas is released into the wait from landfills, livestock and their manure, and from oil and gas wells. The is additionally created once organic product decomposes. It is a heat-trapping greenhouse gas.

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Sulfur Oxides


Sulfur oxides are developed when coal and oil room burned. It’s additionally released indigenous volcanoes. The sulfur oxides mix v water droplets in the atmosphere to develop sulfuric acid, i beg your pardon is a component of mountain rain.