International Journal of Atmospheric Sciences
Volume 2013 (2013), Article ID 503727, 26 pages
http://dx.doi.org/10.1155/2013/503727
Research Article

Radiation and Heat Transfer in the Atmosphere: A Comprehensive Approach on a Molecular Basis

Laser Engineering and Materials Science, Helmut-Schmidt-University Hamburg, Holstenhofweg 85, 22043 Hamburg, Germany

Received 29 April 2013; Accepted 12 July 2013

Academic Editor: Shaocai Yu

Copyright © 2013 Hermann Harde. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

We investigate the interaction of infrared active molecules in the atmosphere with their own thermal background radiation as well as with radiation from an external blackbody radiator. We show that the background radiation can be well understood only in terms of the spontaneous emission of the molecules. The radiation and heat transfer processes in the atmosphere are described by rate equations which are solved numerically for typical conditions as found in the troposphere and stratosphere, showing the conversion of heat to radiation and vice versa. Consideration of the interaction processes on a molecular scale allows to develop a comprehensive theoretical concept for the description of the radiation transfer in the atmosphere. A generalized form of the radiation transfer equation is presented, which covers both limiting cases of thin and dense atmospheres and allows a continuous transition from low to high densities, controlled by a density dependent parameter. Simulations of the up- and down-welling radiation and its interaction with the most prominent greenhouse gases water vapour, carbon dioxide, methane, and ozone in the atmosphere are presented. The radiative forcing at doubled CO2 concentration is found to be 30% smaller than the IPCC-value.