|
Search over 100 encyclopedias and dictionaries: |
Research categories | Follow us on Twitter |
Research categories
View all topics in the newsView all reference sources at Encyclopedia.com |
|||
mesosphere
mesosphere The layer of the atmosphere in the altitude range 50 to 80 km is the mesosphere. Because meso is Greek for ‘middle’, the name is not really appropriate. All significant weather occurs in the troposphere at altitudes below about 15 km, and the mesosphere accounts for less than 0.1 per cent of the mass of the atmosphere.
There are no significant sources of heat in the mesosphere as there are in the stratosphere below and the thermosphere above. At the lower boundary of the mesosphere the temperature is about 0 °C; slightly higher in summer and slightly lower in winter. Absorption of ultraviolet radiation in the stratosphere produces heating below the mesosphere, which leads to this relatively high temperature. Some of this heat is transferred into the lower mesosphere and produces weak vertical motion throughout the mesosphere. As the air rises it cools, and a temperature decrease with height is observed throughout the mesosphere. The decrease in temperature is not, however, as great as would be expected from overturning air and it is about half of the decrease observed in the troposphere. This implies that radiative processes also contribute to the temperature structure of the mesosphere. At the upper boundary of the mesosphere, the mesopause, the temperature is between −110 °C, in summer, and −60 °C, in winter. In summer the mesopause is the coldest part of the entire atmosphere. The low temperatures combined with weak updraughts are sufficient to form tenuous clouds in this region. These clouds are so thin that under normal circumstances they cannot be seen. At twilight, however, there is a period when the lower atmosphere is in the shadow of the Earth while the upper parts of the atmosphere are still in sunlight. At these times the clouds are visible and are therefore referred to as noctilucent clouds. The best viewing conditions are at middle latitudes near the summer solstice, when the mesospheric temperatures reach their lowest values and the twilight hours are at their longest. Charles N. Duncan Bibliography Wallace, J. M. and and Hobbs, P. V. (1977) Atmospheric science: an introductory survey. Academic Press, London. |
|
|
Cite this article
PAUL HANCOCK and BRIAN J. SKINNER. "mesosphere." The Oxford Companion to the Earth. 2000. Encyclopedia.com. 27 May. 2012 <http://www.encyclopedia.com>. PAUL HANCOCK and BRIAN J. SKINNER. "mesosphere." The Oxford Companion to the Earth. 2000. Encyclopedia.com. (May 27, 2012). http://www.encyclopedia.com/doc/1O112-mesosphere.html PAUL HANCOCK and BRIAN J. SKINNER. "mesosphere." The Oxford Companion to the Earth. 2000. Retrieved May 27, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O112-mesosphere.html |
|
Mesosphere
MesosphereBased on the vertical temperature distribution in Earth's atmosphere, four semi-horizontal layers or "spheres" can be distinguished: the troposphere, stratosphere , mesosphere, and thermosphere,. These layers are separated by "pauses," where no change in the temperature occurs with altitude change: the tropopause (between the troposphere and the stratosphere), the stratopause (between the stratosphere and the mesosphere), and the mesopause (between the mesosphere and the thermosphere ). The stratosphere and mesosphere together are called the middle atmosphere, and their region also overlaps with the ionosphere , which is a region defined on the basis of the electric charges of the particles there. The mesosphere, which means middle sphere, is the third layer of Earth's atmosphere, between the stratosphere, and the thermosphere. It is located from about 55 kilometers (35 miles) to 85 kilometers (54 miles) above the surface of Earth. Temperature here decreases with height, so within the mesosphere it is warmest at its lowest level (−5°C, or 23°F), and becomes coldest at its highest level (−80°C, or −112°F). Depending on latitude and season, temperatures in the upper mesosphere can be as low as −140°C (−220°F). The temperature in the mesosphere is lower than the temperature of the troposphere or stratosphere, which makes the mesosphere the coldest among the atmospheric layers. It is colder then Antarctica's lowest recorded temperature, and it is cold enough to freeze water vapor into ice clouds , which can be seen mostly after sunset. Although the air in the mesosphere is relatively mixed, it is very thin, resulting in low atmospheric pressure . At this height, not only concentrations of ozone and water vapor are negligible, air in the mesosphere contains much less oxygen than in the troposphere. The mesosphere is also the layer in which many meteors burn up when they enter the earth's atmosphere, as a result of the collision with some of the gas particles present in this layer. See also Atmospheric composition and structure; Stratosphere and stratopause; Thermosphere |
|
|
Cite this article
"Mesosphere." World of Earth Science. 2003. Encyclopedia.com. 27 May. 2012 <http://www.encyclopedia.com>. "Mesosphere." World of Earth Science. 2003. Encyclopedia.com. (May 27, 2012). http://www.encyclopedia.com/doc/1G2-3437800382.html "Mesosphere." World of Earth Science. 2003. Retrieved May 27, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1G2-3437800382.html |
|
mesosphere
mesosphere The middle layer of Earth's atmosphere, lying above the stratosphere and below the thermosphere, at altitudes of 50–85 km. Temperatures in the mesosphere fall with increasing altitude, reaching a minimum at the mesopause. Measurements from sounding rockets indicate the mesosphere to be extremely dry, but sufficient traces of water vapour are present during the summer months for noctilucent clouds to form near the mesopause.
|
|
|
Cite this article
"mesosphere." A Dictionary of Astronomy. 1997. Encyclopedia.com. 27 May. 2012 <http://www.encyclopedia.com>. "mesosphere." A Dictionary of Astronomy. 1997. Encyclopedia.com. (May 27, 2012). http://www.encyclopedia.com/doc/1O80-mesosphere.html "mesosphere." A Dictionary of Astronomy. 1997. Retrieved May 27, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O80-mesosphere.html |
|
mesosphere
mesosphere
1. Upper-atmospheric layer above the stratopause (at 50 km) through which temperature decreases with height up to about 80 km, where temperatures reach a minimum of about −90°C. This level is the mesopause, an inversion above which temperatures rise again. See also ATMOSPHERIC STRUCTURE. 2. That part of the Earth underlying the asthenosphere. The term is no longer in current use in this sense. |
|
|
Cite this article
AILSA ALLABY and MICHAEL ALLABY. "mesosphere." A Dictionary of Earth Sciences. 1999. Encyclopedia.com. 27 May. 2012 <http://www.encyclopedia.com>. AILSA ALLABY and MICHAEL ALLABY. "mesosphere." A Dictionary of Earth Sciences. 1999. Encyclopedia.com. (May 27, 2012). http://www.encyclopedia.com/doc/1O13-mesosphere.html AILSA ALLABY and MICHAEL ALLABY. "mesosphere." A Dictionary of Earth Sciences. 1999. Retrieved May 27, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O13-mesosphere.html |
|
mesosphere
mesosphere
1. An upper atmospheric layer above the stratopause (at 50 km) through which temperature decreases with height up to about 80 km, where temperatures reach a minimum of about −90°. This level is the mesopause, an inversion above which temperatures rise again. 2. That part of the Earth underlying the asthenosphere. The term is no longer in current use in this sense. |
|
|
Cite this article
MICHAEL ALLABY. "mesosphere." A Dictionary of Ecology. 2004. Encyclopedia.com. 27 May. 2012 <http://www.encyclopedia.com>. MICHAEL ALLABY. "mesosphere." A Dictionary of Ecology. 2004. Encyclopedia.com. (May 27, 2012). http://www.encyclopedia.com/doc/1O14-mesosphere.html MICHAEL ALLABY. "mesosphere." A Dictionary of Ecology. 2004. Retrieved May 27, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O14-mesosphere.html |
|
mesosphere
mes·o·sphere / ˈmezəˌsfi(ə)r; ˈmē-/ • n. the region of the earth's atmosphere above the stratosphere and below the thermosphere, between about 30 and 50 miles (50 and 80 km) in altitude. DERIVATIVES: mes·o·spher·ic / ˌmezəˈsfi(ə)rik; ˌmē-/ adj. |
|
|
Cite this article
"mesosphere." The Oxford Pocket Dictionary of Current English. 2009. Encyclopedia.com. 27 May. 2012 <http://www.encyclopedia.com>. "mesosphere." The Oxford Pocket Dictionary of Current English. 2009. Encyclopedia.com. (May 27, 2012). http://www.encyclopedia.com/doc/1O999-mesosphere.html "mesosphere." The Oxford Pocket Dictionary of Current English. 2009. Retrieved May 27, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O999-mesosphere.html |
|
mesosphere
mesosphere see atmosphere . |
|
|
Cite this article
"mesosphere." The Columbia Encyclopedia, 6th ed.. 2011. Encyclopedia.com. 27 May. 2012 <http://www.encyclopedia.com>. "mesosphere." The Columbia Encyclopedia, 6th ed.. 2011. Encyclopedia.com. (May 27, 2012). http://www.encyclopedia.com/doc/1E1-X-mesosphe.html "mesosphere." The Columbia Encyclopedia, 6th ed.. 2011. Retrieved May 27, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1E1-X-mesosphe.html |
|
|
Search over 100 encyclopedias and dictionaries:
HighBeam™ Research, Inc. © Copyright 2012. All rights reserved.
The Encyclopedia.com advertising network includes:
