The Greenhouse Effect Refresher

Atmospheric Gases: When discussing atmospheric gases, it is useful to refresh one’s memory of the relative concentrations of various gases. To be more useful these will be put in the same units, that is ppmv: parts per million by volume. In the idealized dry atmosphere:

Nitrogen is about 78% of the atmosphere or 780,840 ppmv;

Oxygen is 20.9% or 209,460 ppmv;

Argon is 0.93% of the atmosphere or 9,340 ppmv;

Carbon dioxide is about 0.04% of the atmosphere or 400 ppmv [carbon dioxide varies seasonally and is increasing]. The next greenhouse gas, significantly lower, is

Methane, with about 0.00018% of the atmosphere or 1.79 ppmv;

Nitrous oxide is about 0.0000325% or 0.325 ppmv; and

Ozone is about 0 to 0.000007% or 0 to 0.07 ppmv.

The greenhouse influence of ozone is predominantly in the upper the atmosphere, the stratosphere, where it is created naturally by chemical reactions involving solar ultraviolet radiation (sunlight) and oxygen molecules. It is formed elsewhere in the atmosphere with chemical reactions involving volatile hydrocarbons, oxides of nitrogen, and sunlight. Before pollution control devices, ozone from car exhausts were a problem. In eastern forests of North America, terpenes from trees can create ozone haze under the proper conditions.

Methane and nitrous oxide do not have enough concentration to increase the greenhouse effect significantly.

The kicker to this is water vapor, H2O in a gaseous phase. Over the full atmosphere, it is calculated to be about 0.4% or 4,000 ppmv. In the troposphere water vapor is typically 1% to 4% or 10,000 to 40,000 ppmv. The boundary between the troposphere and stratosphere is called the tropopause. From the NCAR/UCAR web site:

“The troposphere is the lowest layer of Earth’s atmosphere. Most of the mass (about 75-80%) of the atmosphere is in the troposphere. Most types of clouds are found in the troposphere, and almost all weather occurs within this layer. The troposphere is by far the wettest layer of the atmosphere; all of the layers above contain very little moisture.

“The bottom of the troposphere is at Earth’s surface. The troposphere extends upward to about 10 km (6.2 miles or about 33,000 feet) above sea level. The height of the top of the troposphere varies with latitude (it is lowest over the poles and highest at the equator) and by season (it is lower in winter and higher in summer). It can be as high as 20 km (12 miles or 65,000 feet) near the equator, and as low as 7 km (4 miles or 23,000 feet) over the poles in winter.”

By the tropopause, liquid water and water vapor freeze out and above it, the concentration is only about 4 ppm. See:


CO2 is not the earth’s temperature control knob, it is water vapor. The major source of water vapor is the planet’s oceans, which are warmed by the sun. A warm Pacific produces more water vapor and more rain, cooler Pacific ocean produces less water vapor and more drought. It is a process that has been going on since the oceans were created.  The more water vapor in the air, the more heat it can hold, the same is not true of CO2.  Water vapor, not CO2 is is the temperature control knob for the planet, the problem is Mother Nature is the only one with access.

About Russ Steele

Freelance writer and climate change blogger. Russ spent twenty years in the Air Force as a navigator specializing in electronics warfare and digital systems. After his service he was employed for sixteen years as concept developer for TRW, an aerospace and automotive company, and then was CEO of a non-profit Internet provider for 18 months. Russ's articles have appeared in Comstock's Business, Capitol Journal, Trailer Life, Monitoring Times, and Idaho Magazine.
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2 Responses to The Greenhouse Effect Refresher

  1. cognog2 says:

    If you are interested in how the water control knob works have a look at the discussion paper at https:// on clouds and IPCC logic. a pragmatic view to tickle your curiosity.


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