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Topic: Polar mesospheric cloud

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	Puzzling height of polar clouds linked to solar radiation
		Polar mesospheric clouds are the highest on Earth, forming at an altitude of about 52 miles.
		The formation of polar mesospheric clouds is a complex process that depends on the temperature, water vapor and vertical wind structure of the mesopause region, Gardner said.
		“The weaker polar mesospheric clouds at Rothera may be related to differences in temperature and water vapor in the mesopause region at Rothera compared with the South Pole,” said Patrick Espy, a senior scientist with the British Antarctic Survey.
	www.news.uiuc.edu /news/04/0126gardner.html (1091 words)

	[No title]
		A burst of mesospheric cloud activity over Antarctica in January 2003 was caused by the exhaust plume of the space shuttle Columbia during its final flight, reports a team of scientists who studied satellite and ground-based data from three different experiments.
		From January 19-26, however, 18 hours of cloud observations were recorded." The increase in polar mesospheric clouds was also observed with the Solar Backscatter Ultraviolet instrument on the NOAA-16 satellite.
		Additional evidence that the shuttle plume was responsible for the burst of cloud activity can be found in the mesopause temperature, inferred from the iron observations near an altitude of 56 miles, the researchers report.
	www.physorg.com /printnews.php?newsid=4972 (645 words)

	oe magazine - air time (Site not responding. Last check: 2007-11-06)
		Clearly, polar upper-atmosphere data are vital for testing the atmospheric circulation models that underlie our understanding of global climate change, but collecting data from this remote and inaccessible region with sophisticated remote-sensing instruments is challenging.
		Polar mesospheric clouds form at altitudes near 85 km over each of the polar caps during mid-summer, when temperatures fall below –125° C. These clouds are the highest on Earth.
		Their visual counterparts are the summertime noctilucent clouds, which typically are seen at latitudes greater than 50° during the night, when the surface is in darkness but the upper atmosphere is still sunlit.
	www.oemagazine.com /fromTheMagazine/apr01/airtime.html (1571 words)

	ENVIRONMENTAL SCIENCE: IRON AND POLAR MESOSPHERIC CLOUDS
		Because the PMC backscatter signals are nearly identical at 372 and 374 nm, whereas the Fe signals are substantially different (the relative population of the higher multiplet is 1.2% at 145 K), the PMC signal can be eliminated from the 372-nm data by subtracting the 374-nm return signal and scaling the difference.
		4) In summary: Polar mesospheric clouds are thin layers of nanometer-sized ice particles that occur at altitudes between 82 and 87 kilometers in the high-latitude summer mesosphere.
		Clouds, after all, are the most visible manifestation of weather in all its forms, and their prediction should be more than an object of curiosity.
	scienceweek.com /2004/sc040806-3.htm (968 words)

	Abstracts
		Polar mesosphere summer echoes are strong radar echoes from an altitude range of about 80 – 90 km mainly observed in the VHF range during summer months at polar latitudes.
		Polar mesospheric clouds were observed above the North Pole and Coast of Alaska in the summer of 1999 and at the South Pole in two austral summer seasons from 1999 to 2001 by an airborne/ground-based Fe Boltzmann Temperature Lidar.
		Mesosphere summer echoes (MSE) at mid-latitudes are a rare phenomenon in contrast to the polar mesosphere summer echoes (PMSE) at arctic latitudes.
	isr.sri.com /nlc2001/abstracts_submitted.html (13137 words)

	Columbia's Last Flight Formed Antarctic Clouds
		WASHINGTON - A burst of high altitude cloud activity over Antarctica in January 2003 was caused by the exhaust plume of the space shuttle Columbia during its final flight, reports a team of scientists who studied satellite and ground-based data from three different experiments.
		Polar mesospheric clouds are the highest on Earth, forming at an altitude of about 84 kilometers [52 miles].
		Additional evidence that the shuttle plume was responsible for the burst of cloud activity can be found in the mesopause temperature, inferred from the iron observations near an altitude of 90 kilometers [56 miles], the researchers report.
	www.spacearchive.info /news-2005-07-06-agu.htm (722 words)

	pmc_page.html
		Polar mesospheric clouds (PMCs) occur in both hemispheres near the summer solstice at high latitudes and altitudes near the mesopause (~82 km) [e.g., Alpers et al.
		Wegener [1912] was the first to suggest that these clouds could be composed of water ice, and this theory has persisted because PMCs have been associated with ice supersaturations and because their growth appears to be an exponential function of temperature [e.g., Rusch et al.
		The HALOE data are averages based on 16 PMC measurements from July 25 to August 4, 1997, between 62°N and 72°N latitude.
	gwest.gats-inc.com /research/pmcs/pmc_page.html (463 words)

	The polar mesospheric cloud mass in the Arctic summer
		We infer the polar mesospheric cloud (PMC) mass throughout the Arctic summer using results from two sets of satellite observations and a microphysical model.
		Solar backscatter ultraviolet (SBUV) PMC observations in July 1999 indicate a burst of activity persisting for ∼8 days after a space shuttle launch and averaging 262 ± 52 t near 4.7 local time.
		This overprediction is within the time-dependent variability of ice formation and the uncertainties of temperature, water vapor, and vertical winds used to initialize the model.
	www.agu.org /pubs/crossref/2005/2004JA010566.shtml (242 words)

	AIM - Education and Public Outreach
		Gumbel, J. et al., Influences of ice particles on the ion chemistry of the polar summer mesosphere, J. Geophys.
		Shettle, E.P., S.P. Burton, J.J. Olivero, G.E. Thomas, and L.W. Thomason, "SAGE II Measurements of Polar Mesospheric Clouds", In the Memoirs Brit.
		Thomas, G. Mesospheric clouds and the physics of the mesopause region.
	aim.hamptonu.edu /library/1library.html (2781 words)

	sciforums.com - Polar Mesospheric Clouds (Site not responding. Last check: 2007-11-06)
		Appearing electric blue, most of these clouds are formed near the mesopause and some of their counterparts, another mesospheric cloud, noctilucent clouds, appear near the stratopause.
		PMC's or Polar Mesospheric Clouds have a smokey look, while PSC's also called Mother Of Pearl Clouds look like a typical cirrostratus or some kind of rough smoke...
		As far as I know, those clouds and the resulting light emitted are harmless.
	www.sciforums.com /printthread.php?t=39656 (403 words)

	Noctilucent Clouds (Site not responding. Last check: 2007-11-06)
		Clouds at extremely high altitude, about 85 km, that literally (as the name suggests) shine at night.
		They form in the cold, summer polar mesopause and are believed to be ice crystals.
		Because of their high altitude, in a very dry part of the atmosphere, noctilucent clouds are rather an enigma and are being studied by a number of people around the world.
	lasp.colorado.edu /noctilucent_clouds (115 words)

	What are NLC?
		The clouds reside at an altitude of 80-85Km with an average altitude of 83Km.
		Polar Summer Mesospheric Echoes (PSME) are very strong radar echoes which appear during the months of the NLC season, May to August, with their greatest frequency occurring in June and July, at the time when NLC are also most frequent.
		The mesosphere is a sort of "no-mans land" in the atmosphere.
	freespace.virgin.net /eclipsing.binary/whatarenlc.html (1879 words)

	PMC article - PMC Polar mesospheric cloud Production Material Control private - What-Means.com (Site not responding. Last check: 2007-11-06)
		PMC article - PMC Polar mesospheric cloud Production Material Control private - What-Means.com
		If you followed a link here, you might want to go back and fix that link to point to the appropriate specific page.
		PMC article - PMC definition - what means PMC
	www.what-means.com /encyclopedia/PMC (89 words)

	HALOE PMC project
		The goal of this three year project is to advance the understanding of polar mesospheric clouds (PMCs) and their environment using measurements from the Halogen Occultation Experiment (HALOE).
		The relationship between polar mesospheric clouds and water vapor enhancement in the polar summer mesosphere.
		Wrotny, J., and J. Russell, The Identification and Characterization of Polar Mesospheric Clouds (PMCs) in HALOE data, CEDAR Workshop, Longmont, CO, June 15-20, 2003.
	gwest.gats-inc.com /haloe_pmc_project/HALOE_PMC_project.html (555 words)

	Geomagnetism and Aeronomy (Site not responding. Last check: 2007-11-06)
		Noctilucent and mesospheric clouds are formed close to the mesopause at a height of about 82 km, if temperature and humidity are favorable.
		The link between the occurrence of polar mesospheric clouds and noctilucent clouds and the mesospheric temperature profile points to the possibility of temperature measurements for predictions of polar mesospheric and noctilucent clouds occurrences.
		Comparison of seasonal variations of temperature and cloud occurrence has shown an agreement within 20%; thus this provides the possibility of prediction of polar mesospheric cloud and noctilucent cloud occurrences from temperature measurements.
	eos.wdcb.ru /transl/gma/9405/pap32.htm (205 words)

	Papers (Site not responding. Last check: 2007-11-06)
		Swenson, G. R., and C. Gardner (1998a), Analytical models for the responses of the mesospheric OH and Na layers to atmospheric gravity waves, J. Geophys.
		Bishop, R. Larsen, J. Hecht, A. Liu, and C. Gardner (2004), TOMEX: Mesospheric and lower thermospheric diffusivities and instability layers, J. Geophys.
		Hecht, J. Liu, R. Walterscheid, and R. Rudy (2005), Maui Mesosphere and lower thermosphere (Maui MALT) observations of the evolution of Kelvin-Helmholtz billows formed near 86 km altitude, J. Geophys.
	eoslserver.csl.uiuc.edu /home/papers.htm (3694 words)

	IUGG 2003 Scientific Program (Site not responding. Last check: 2007-11-06)
		A Polar Mesospheric Cloud (PMC) was detected by a Rayleigh lidar at Davis, Antarctica (68.6°S, 78.0°E) over a two hour period on 09 January 2002.
		Over the course of the observations, the cloud tended to drift down inaltitude, and showed evidence of apparent quasi-periodic vertical motion with an amplitude of 500 metres and a period of 1 hour.
		The Davis PMC had an altitudeapproximately 1km lower than the mean altitude of clouds observed at South Pole at the equivalent time of year, and was slightly above the lower limit of cloud altitudes measured at South Pole.
	www.jamstec.go.jp /jamstec-e/iugg/htm/abstract/abst/jsm06/020217-2.html (311 words)

	Polar Mesospheric Cloud (Site not responding. Last check: 2007-11-06)
		Believed to consist of ice particles of dimensions less than 0.1 µm, polar mesospheric (or noctilucent) clouds offer a splendid summertime light show to northern inhabitants.
		During the long summer twilight these high altitude (83 km) clouds are visible by direct solar illumination, while the lower atmosphere is in shadow.
		The cloud color is generally white to silvery-blue, primarily due to the Rayleigh-like scattering properties of the tiny particles, and secondarily due to partial removal of red light from absorption in the Chappuis bands of atmospheric ozone.
	www-sage2.larc.nasa.gov /data/version_6.1/HTML/pmc.html (251 words)

	Sept 26 2003 journal club (Site not responding. Last check: 2007-11-06)
		SNOE observations of PMCs have a significant advantage over other PMC measurements in that it is able to observe them globally each day.
		Further analysis shows that in fact, PMCs are modulated by a dominant 5-day wave, which is present in all measured north and south seasons.
		This is the first direct wave analysis performed on PMC measurements on a global scale and gives a strong indication of the dynamical effects on PMC formation.
	ffden-2.phys.uaf.edu /Sept_26_2003_journal_club.htm (198 words)

	The Weather Notebook: Polar Cloud (Site not responding. Last check: 2007-11-06)
		Because of their high altitude, in a very dry part of the atmosphere, noctilucent clouds are rather an enigma.
		A rare and mysterious cloud type has been sighted for the first time in the heart of the nation.
		Noctilucent Clouds (NLC) or Polar Mesospheric Clouds (PMC) are the highest on Earth.
	www.weathernotebook.org /transcripts/2001/01/08.html (347 words)

	Exploring The Unknown World Of "Cloud Nine"
		LASP was selected to design and build the Cloud Imaging and Particle Size instrument, or CIPS, which will image the polar mesospheric clouds and the sizes of particles within them, he said.
		Noctilucent, or "night-shining" clouds occur in the summer in the mesosphere, which is the coldest part of the atmosphere, said Thomas.
		The clouds, which appear each year in the far northern and southern latitudes, were spotted over Colorado for the first time on June 22, 1999, from Coal Creek Canyon near Boulder.
	www.spacedaily.com /news/climate-02w.html (1113 words)

	Improved mesospheric temperature, water vapor and polar mesospheric cloud extinctions from HALOE
		Previous HALOE retrievals did not account for polar mesospheric clouds (PMCs) and were biased whenever PMCs were in the sample volume.
		In the new algorithm we eliminate this bias by retrieving and correcting for PMC extinction, and we optimize the algorithm for this region of the atmosphere.
		Citation: McHugh, M. Hervig, B. Magill, R. Thompson, E. Remsberg, J. Wrotny, and J. Russell III (2003), Improved mesospheric temperature, water vapor and polar mesospheric cloud extinctions from HALOE, Geophys.
	www.agu.org /pubs/crossref/2003/2002GL016859.shtml (234 words)

	sciforums.com - Polar Mesospheric Clouds (Site not responding. Last check: 2007-11-06)
		No. Nacreous Clouds are stratospheric clouds when cold tropopause air is carried up my high surface winds and clashes with the bitter, dry, warm air of the stratosphere.
		Think of the formation of the Nacreous reversed from a normal cloud.
		I dont remember but those lights are very bad for the atmosphere.
	www.sciforums.com /showthread.php?t=39656 (377 words)

	PMC’s and the water frost point in the Arctic summer mesosphere (Site not responding. Last check: 2007-11-06)
		In August, 1997 the Middle Atmosphere High Resolution Spectrograph Investigation (MAHRSI) obtained vertical profiles of OH number density and polar mesospheric cloud (PMC) brightness by scanning the limb up to 71° N while the Cryogenic Infrared Spectrometers and Telescopes for the Atmosphere (CRISTA) obtained co-located vertical profiles of temperature.
		MAHRSI OH densities are converted to water vapor using a one-dimensional model that assumes photochemical equilibrium.
		Additionally, we find that not only is supersaturation an insufficient condition for a PMC but also that PMCs can exist in apparently unsaturated air.
	www.crista.uni-wuppertal.de /papers/Abstracts/084-PMCs.html (167 words)

	LASP :: SNOE :: Data :: Publications
		Merkel, A.W., G.E. Thomas, and S.M. Bailey, Global Images of Polar Mesospheric Clouds from the SNOE Spacecraft, Intertional Workshop on Layered Phenomena in the Mesopause Region, Monterey, CA, Oct. 10 - 12, 2001.
		Bailey, S.M., et al., The Climatology of Polar Mesospheric Clouds From the Student Nitric Oxide Explorer, AGU Spring Meeting, Boston, MA, May 18 - June 1, 2001.
		Thomas, G.E., et al., Observations of Polar Mesospheric Clouds by the Student Nitric Oxide Explorer, AGU, Fall Meeting, San Francisco, CA, Dec. 13-17, 1999.
	lasp.colorado.edu /snoedata/publications (1891 words)

	Dr. Michael E. Schlesinger (Site not responding. Last check: 2007-11-06)
		Proceedings of the 11th International Conference on Clouds and Precipitation, Montreal, 17-21 August 1992.
		In Clouds in Climate II, A WRCP Workshop on Modeling and Observations, NASA Workshop Report, July 1988, pp.
		A review of the current parameterizations of clouds in general circulation models and description of a more physically-based method.
	crgd.atmos.uiuc.edu /people/mes.html (5138 words)

	AIM - Education and Public Outreach
		Bailey, S. M., Merkel, A. W., Thomas, G. E., Carstens, J. Observations of polar mesospheric clouds by the Student Nitric Oxide Explorer.
		Merkel, A. W., Dynamical influences on polar mesospheric clouds observed from the student nitric oxide explorer,
		Thomas, G. E., Are noctilucent clouds harbingers of global change in the middle atmosphere?,
	aim.hamptonu.edu /outreach/3-1-2ref.html (2783 words)

	[No title]
		Fricke, 1997: Observations of Antarctic polar* stratospheric clouds by POAM II: 1994-1996.
		Massie, S., D. Baumgardner, and J. Dye, 1998: Estimation of polar stratospheric cloud volume and area densities from UARS, stratospheric aerosol measurement II, and polar ozone and aerosol measurement II extinction data.
		Baumgardner, D., and G. Raga, 1998: WMO workshop on the measurement of cloud* properties for the forecasts of weather and climate.
	www.ncar.ucar.edu /ASR98/98pubs.html (14619 words)

	Mount Washington Observatory: Glossary of Weather Terms (Site not responding. Last check: 2007-11-06)
		- Gray, dark clouds with no clearly defined base which are associated with continuous precipitation that may or may not reach the ground.
		The clouds are several thousand feet thick and will completely block the Sun.
		Their precipitation may consist of snow, sleet, rain, or drizzle, but not hail (since there is no convection).
	www.mountwashington.org /glossary/glosn-o.html (684 words)

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