Three-fourths of all air resides in the troposphere, the lowest layer the the earth atmosphere. Waiting is a mixture of gases, many of i m sorry are naturally occurring. Air likewise contains a significant amount that human-made waiting pollutants, consisting of some that are not safe to breathe and also some that heat our planet’s climate. The troposphere likewise contains water in all 3 phases (liquid, solid, and also gas) and also solid particles, dubbed aerosols.

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


The most abundant naturally arising gas is Nitrogen (N2), which provides up around 78% of air. Oxygen (O2) is the second most abundant gas at around 21%. The inert gas Argon (Ar) is the third most numerous gas in ~ .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 to the water cycle, the lot of water in the wait is constantly changing. The lower troposphere deserve to contain approximately 4% water vapor (H2O) in areas near the tropics, when the poles contain only trace amounts of water vapor. The concentration that water vapor decreases substantially with altitude. The top troposphere has substantially less water vapor 보다 air close to the surface, the stratosphere and also mesosphere have almost no water vapor, and the thermosphere includes none in ~ all.


Air additionally contains small solid particles dubbed aerosols, such as dust, sea salt, and also ash from erupting volcanoes or forest fires. Many of this particles room so small that they space microscopic. Rather are big enough come see. Aerosols affect climate by helping clouds type and shading the earth by scattering or taking in sunlight. In the critical century, manufacturing and widespread use of combustion engines have actually increased the variety of aerosols in the environment as particulate matter spews indigenous smokestacks and also exhaust pipes. Burning wood and other products also add particles to the air.

Atmospheric Chemistry

Like whatever on Earth, the air is make of chemicals. The chemicals in the wait often integrate with each other, or with various other chemicals native the earth surface, with chemical reactions. Countless of these chemical reactions assist maintain healthy and balanced natural environments and are an essential for plants and animals. Nitrogen gas in the environment does practically nothing, yet nitrogen elsewhere on earth is vital for life. Through the nitrogen cycle, nitrogen provides its means into soil and also water, binds with other elements, and also can be provided by living things. Oxygen indigenous the atmosphere causes oxidation reactions the help breakdown matter and also release nutrients right into soils, and also is supplied by humans and also animals in moving respiration.

Atmospheric chemistry in the troposphere is also influenced through human-made chemicals that deserve to negatively influence human health and also the environment. For example:

Smog, which is mostly made of ozone and also particulate carbon (soot) emitted through coal-burning power plants, causes damage to the lung of humans and animals. Factories the burn fossil fuels also release sulfur and nitrogen dioxides, which combine 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 below lists the significant gas components and also their role in the atmosphere. Click on each molecule name to learn an ext about them.

GasChemical & MolecularStructureRole in the atmosphere



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

Nitrogen Oxides


Nitrogen oxides are air pollutants that add to the development of ozone. They additionally create nitric acid, i m sorry is component of acid rain, once they mix through water droplets in the air.



Oxygen provides up 21% the the atmosphere. The is extremely reactive and also forms compound with many other chemicals, and also is crucial for respiration in living things.



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



Argon provides up about 1% that the atmosphere and also comes greatly from the decay of potassium in the earth’s crust. The is one inert gas, which method that it does not react with various other chemicals.

Water Vapor


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

Carbon Dioxide

Carbon dioxide normally composes around .03% the the atmosphere, yet the quantity is increasing due to the burning of fossil fuels. Plants and eubacteria use carbon dioxide during photosynthesis. Humans, various other animals, and also plants add 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. It is a gift gas.



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

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Sulfur Oxides


Sulfur oxides are produced when coal and oil room burned. It’s additionally released from volcanoes. The sulfur oxides mix through water droplets in the environment to create sulfuric acid, which is a component of acid rain.