On earth, two elements, nitrogen () and oxygen (), make up almost 99% of the volume of clean, dry air. Most of the remaining 1% is accounted for by the inert gaseous element, argon (Ar). Argon and the tiny percentage of remaining gases are referred to as trace gases.
Certain trace atmospheric gases help to heat up our planet because they appear transparent to incoming visible (shortwave) light but act as a barrier to outgoing infrared (longwave) radiation. These special trace gases are often referred to as "greenhouse gases" because a scientist in the early 19th century suggested that they function much like the glass plates found on a greenhouse used for growing plants.
The earth's atmosphere is composed of gases (for example, and ) of just the right types and in just the right amounts to warm the earth to temperatures suitable for life. The effect of the atmosphere to trap heat is the true "greenhouse effect."
We can evaluate the effect of greenhouse gases by comparing Earth with its nearest planetary neighbors, Venus and Mars. These planets either have too much greenhouse effect or too little to be able to sustain life as we know it. The differences between the three planets have been termed the "Goldilocks Principle" (Venus is too hot, Mars is too cold, but Earth is just right). http://www.ucar.edu/learn/1_1_2_1t.htm
In this lesson, students learn how atmospheric composition and circulation impact the generation of storms. Students examine the primary and variable gases that...
Ecosystems and Human Well-Being: Volume 1: Current State and Trends: Air Quality and ClimateLast Updated on 2014-11-17 12:15:25
This is Chapter 13 of the Millenium Ecosystem Assessment report Ecosystems and Human Well-Being: Volume 1: Current State and Trends
Coordinating Lead Authors: Jo House, Victor Brovkin
Lead Authors: Richard Betts, Bob Constanza, Maria Assunçao Silva Dias, Beth Holland, Corinne Le Quéré, Nophea Kim Phat, Ulf Riebesell, Mary Scholes
Contributing Authors: Almut Arneth, Damian Barratt, Ken Cassman, Torben Christensen, Sarah Cornell, Jon Foley, Laurens Ganzeveld, Thomas Hickler, Sander Houweling, Marko Scholze, Fortunat Joos, Karen Kohfeld, Manfredi Manizza, Denis Ojima, I. Colin Prentice, Crystal Schaaf, Ben Smith, Ina Tegen, Kirsten Thonicke, Nicola Warwick
Review Editors: Pavel Kabat, Shuzo Nishioka
Ecosystems, both natural and managed, exert a strong influence on climate and air quality. Ecosystems are both sources and sinks of greenhouse gases,... More »
Climate changeLast Updated on 2014-11-15 14:23:07
Editor's Note: This article was compiled and edited by Mohan Munasinghe, Cutler J. Cleveland, and Laura De Angelo. In the interests of maintaining scientific accuracy, this article is derived directly from material in the Synthesis Report and the Technical Summary of Working Group I, "The Physical Science Basis," of the Fourth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC). The full Synthesis Report and Technical Summary are reproduced in this Encyclopedia, and are available in their original PDF forms at the IPCC web site. The relevant IPCC Lead Authors are listed in the Acknowledgments at the end of this article.
Climate change refers to a change in the state of the climate that can be identified by changes in the average and/or the variability of its properties (e.g., temperature, precipitation), and that persists for an extended... More »
Agriculture and Greenhouse GasesLast Updated on 2014-11-09 17:57:31
In both industrialized and developing nations, agricultural production of greenhouse gases (GHG) is a significant component of worldwide GHG emissions. There are major contributions to methane production from livestock grazing and rice farming, as well as incomplete combustion of petroleum products in mechanized agricultural equipment. In developing countries agricultural production of greenhouse gases is a much higher percentage of total GHG emissions than for developed countries. For example, rice farming in China and Southeast Asia and livestock grazing in several South American countries contributes proportionately more agricultural GHG than corresponding farming activity in most Western countries. Elimination of overgrazing practises and reduction of dependence of rice farming provide significant opportunities for reducing GHG emissions.
There are also large contributions to... More »
ClimateLast Updated on 2014-10-01 10:48:54
Climate is the typical pattern of conditions of the earth’s atmosphere over a given region, as defined by factors such as temperature, air pressure. humidity, precipitation, sunlight, cloudiness, and winds. The World Meteorological Organization defines climate as "the statistical description in terms of the mean and variability of relevant quantities over a period of time," where an appropriate period is typically at least thirty years. Climate can be assessed at different, overlapping geographic regions. For example, Earth is thought to have a climate that is distinct from that of other planets, while different regions of Earth are also thought to have distinct climate types. Climate is often described as the "average" conditions; however, since daily and seasonal variability (including extremes) are critical determinants, using the term... More »
Global Rise Reported in 2013 Greenhouse Gas Emissions Last Updated on 2014-09-22 11:38:01Global emissions of greenhouse gases jumped 2.3 percent in 2013 to record levels, scientists reported Sunday, in the latest indication that the world remains far off track in its efforts to control global warming. Click to read more.
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