World Library  
Flag as Inappropriate
Email this Article


Article Id: WHEBN0000047466
Reproduction Date:

Title: Mesopause  
Author: World Heritage Encyclopedia
Language: English
Subject: Mesosphere, Turbopause, Earth's atmosphere, Atmosphere of Earth, Outline of earth science
Publisher: World Heritage Encyclopedia


The mesopause is the temperature minimum at the boundary between the mesosphere and the thermosphere atmospheric regions. Due to the lack of solar heating and very strong radiative cooling from carbon dioxide, the mesopause is the coldest region on Earth with temperatures as low as -100°C (-146°F or 173 K).[1] The altitude of the mesopause for many years was assumed to be at around 85 km (52 mi.), but observations to higher altitudes and modeling studies in the last 10 years have shown that in fact the mesopause consists of two minima - one at about 85 km and a stronger minimum at about 100 km. (62 mi.)[2]

An interesting feature is that the summer mesopause is cooler than the winter. This is sometimes referred to as the mesopause anomaly. It is due to a summer-to-winter circulation giving rise to upwelling at the summer pole and downwelling at the winter. Air rising will expand and cool resulting in a cold summer mesopause and conversely downwelling air results in compression and associated increase in temperature at the winter mesopause. In the mesosphere the summer-to-winter circulation is due to gravity wave dissipation, which deposits momentum against the mean east-west flow, resulting in a small north-south circulation.[3]

In recent years the mesopause has also been the focus for studies on global climate change associated with increases in CO2. Unlike the troposphere, where greenhouse gases result in the atmosphere heating up, increased CO2 in the mesosphere acts to cool the atmosphere due to increased radiative emission by CO2. This results in a measurable effect - the mesopause should become cooler with increased CO2. Observations do show a decrease of temperature of the mesopause, though the magnitude of this decrease varies and is subject to further study.[4] Modeling studies of this phenomenon have also been carried out.[5][6][7]

See also


  1. ^ International Union of Pure and Applied Chemistry. "mesosphere". Compendium of Chemical Terminology Internet edition
  2. ^ Xu, Jiyao; Liu, H.-L.; Yuan, W.; Smith, A. K.; Roble, R. G.; Mertens, C. J.; Russell, J. M.; Mlynczak, M. G., "Mesopause structure from Thermosphere, Ionosphere, Mesosphere, Energetics, and Dynamics (TIMED)/Sounding of the Atmosphere Using Broadband Emission Radiometry (SABER)", Journal of Geophysical Research, Volume 112, Issue D9
  3. ^ The Physics of Atmospheres, John Theodore Houghton, section and references therein of The general circulation of the middle atmosphere
  4. ^ Beig, G., Keckhut, P., Lowe, R.P., et al., 2003. Review of mesospheric temperature trends. Rev. Geophys. 41 (4), 1015.
  5. ^ Roble, R.G., Dickinson, R.E., 1989. How will changes in carbon-dioxide and methane modify the mean structure of the mesosphere and thermosphere? Geophys. Res. Lett. 16 (12), 1441-1444.
  6. ^ Akmaev, R.A., Fomichev, V.I., Zhu, X., 2006. Impact of middle-atmospheric composition changes on greenhouse cooling in the upper atmosphere. J. Atmos. Solar-Terr. Phys. 68 (17), 1879-1889.
  7. ^ Ingrid Cnossen, Matthew J. Harris, Neil F. Arnold and Erdal Yiğit, "Modelled effect of changes in the CO2 concentration on the middle and upper atmosphere: sensitivity to gravity wave parameterization", Journal of Atmospheric and Solar-Terrestrial Physics (accepted October 2008 - in Press)
This article was sourced from Creative Commons Attribution-ShareAlike License; additional terms may apply. World Heritage Encyclopedia content is assembled from numerous content providers, Open Access Publishing, and in compliance with The Fair Access to Science and Technology Research Act (FASTR), Wikimedia Foundation, Inc., Public Library of Science, The Encyclopedia of Life, Open Book Publishers (OBP), PubMed, U.S. National Library of Medicine, National Center for Biotechnology Information, U.S. National Library of Medicine, National Institutes of Health (NIH), U.S. Department of Health & Human Services, and, which sources content from all federal, state, local, tribal, and territorial government publication portals (.gov, .mil, .edu). Funding for and content contributors is made possible from the U.S. Congress, E-Government Act of 2002.
Crowd sourced content that is contributed to World Heritage Encyclopedia is peer reviewed and edited by our editorial staff to ensure quality scholarly research articles.
By using this site, you agree to the Terms of Use and Privacy Policy. World Heritage Encyclopedia™ is a registered trademark of the World Public Library Association, a non-profit organization.

Copyright © World Library Foundation. All rights reserved. eBooks from Project Gutenberg are sponsored by the World Library Foundation,
a 501c(4) Member's Support Non-Profit Organization, and is NOT affiliated with any governmental agency or department.