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magnetosphere |
The region surrounding a celestial body where its magnetic field controls the motions of charged particles. The Earth's magnetic field is dipolar in nature. That is, it behaves as if produced by a giant bar magnet located near the center of the planet with its north pole tilted several degrees from Earth's geographic north pole.
The Earth's magnetic field presents an obstacle to the solar wind, as a rock in a running stream of water. This obstacle is called a bow shock. The bow shock slows down, heats, and compresses the solar wind, which then flows around the rest of Earth's magnetic field. See Van Allen belts. |
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Marshall Space Flight Center (MSFC) |
The George C. Marshall Space Flight Center, located in Huntsville, Alabama, is responsible for developing spacecraft hardware and systems, and is perhaps best known for its role in building the Saturn rockets that sent astronauts to the Moon during the Apollo program. It is NASA's primary center for space propulsion systems and plays a key role in the development of payloads to be flown on the shuttle (such as Spacelab). MSFC also manages two other NASA sites: the Michoud Assembly Facility in New Orleans where the Shuttle's external tanks are manufactured, and the Slidell Computer Complex in Slidell, Louisiana, which provides computer support to Michoud and to NASA's John C. Stennis Space Center. MSFC Web Site |
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mass balance |
The term ‘mass balance’ is often used by glaciologists to describe the
difference between all of the ice that is added to a glacier, and all of the ice
the glacier loses over a period of time. Ice sheets and glaciers can lose mass due
to melting, calving, evaporation, etc. They can gain mass from direct
precipitation, avalanching, and windblown snow. The net result of all these
outputs and inputs of ice are then the glacier’s mass balance.
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mean sea level |
The average height of the sea surface, based upon hourly observation of the tide height on the open coast or in adjacent waters that have free access to the sea. In the United States, it is defined as the average height of the sea surface for all stages of the tide over a nineteen year period. Mean sea level, commonly abbreviated as MSL and referred to simply as 'sea level,' serves as the reference surface for all altitudes in upper atmospheric studies. |
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Measurements of Pollution in the Troposphere (MOPITT) |
MOPITT will fly aboard Terra as part of NASA's Earth Observing System(EOS). It is an instrument designed to enhance our knowledge of the lower atmosphere and to particularly observe how it interacts with the land and ocean biospheres. MOPITT is a scanning radiometer employing gas correlation spectroscopy to measure upwelling and reflected infrared radiance in three absorption bands of carbon monoxide and methane. |
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megabit |
(mbps) Millions of bits per second. A unit of information transfer rate -- e.g. Ethernet can carry 10 mbps. |
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mesopause |
The upper boundary of the mesosphere where the temperature of the atmosphere reaches its lowest point. |
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mesosphere |
The atmospheric layer above the stratosphere, extending from about 50 to 85 kilometers altitude. The temperature generally decreases with altitude. |
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metabolism |
the sum of all the chemical and physical processes within a living organism, including anabolism and catabolism
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metadata |
Information describing the content or utility of a data set. For example, the dates on which data were procured are metadata. |
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Meteor |
The former Soviet Union's series of polar orbiting weather satellites. The Meteor satellites transmit images in a system compatible with the NOAA polar-orbiting satellites. |
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meteorite |
a solid mass of mineral or rock matter that has fallen to the earth's surface from outer space without being completely vaporized in the atmosphere.
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meteorology |
Study of the atmosphere and its phenomena. |
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METEOSAT |
(METEOrological SATellite) Europe's geostationary weather satellite, launched by the European Space Agency and now operated by an organization called Eumetsat. |
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Methane (CH4) |
A hydrocarbon that is a greenhouse gas. Methane is produced through anaerobic (without oxygen) decomposition of waste in landfills, animal digestion, decomposition of animal wastes, production and distribution of natural gas and oil, coal production , and incomplete fossil fuel combustion. The atmospheric concentration of methane has been shown to be increasing at a rate of about 0.6% per year and the concentration of about 1.7 parts per million by volume (ppmv) is more than twice its preindustrial value. However, the rate of increase of methane in the atmosphere may be stabilizing. |
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microbe |
any microorganism
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micrometer |
One millionth of a meter, used to measure wavelengths in the
electromagnetic spectrum. Also known as a "micron" or жm |
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microwave |
Electromagnetic radiation with wavelengths between about 1000 micrometers and one meter. |
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middle infrared |
Electromagnetic radiation between the near infrared and the thermal infrared, about 2-5 micrometers. |
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millibar (mb) |
One thousandth of a bar, a unit of atmospheric pressure. The average atmospheric pressure at sea level is 1.01325 bars or 1013.25 mb. See pascal (Pa), atmospheric pressure. |
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model (noun) |
A mathematical representation of a process, system, or object developed to understand its behavior or to make predictions. The representation always involves certain simplifications and assumptions. |
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Moderate-resolution Imaging Spectroradiometer (MODIS) |
MODIS will fly aboard Terra as part of NASA's Earth Observing System (EOS). It will view the entire surface of the Earth every 1-2 days, making observations in 36 co-registered spectral bands, at moderate resolution (0.25 - 1 km), of land and ocean surface temperature, primary productivity, land surface cover, clouds, aerosols, water vapor, temperature profiles, and fires. See MODIS Web Site. |
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monsoon |
A name for seasonal winds, first applied to the winds over the Arabian Sea that blow for six months from the northeast and for six months from the southwest. The term has been extended to similar winds in other parts of the world (i.e., the prevailing west to northwest winds of summer in Europe have been called the European monsoon). The primary cause for these seasonal winds is the much greater annual variation of temperature over large land areas compared with neighboring ocean surfaces, causing an excess of pressure over the continents in winter and a deficit in summer, but other factors, such as topography of the land, also have an effect. The monsoons are strongest in the southern and eastern sides of Asia, but also occur along the coasts of tropical regions wherever the planetary circulation is not strong enough to inhibit them. The monsoon climate can be described as a long winter-spring dry season, which includes a cold season followed by a short hot season just preceding the rains; a summer and early autumn rainy season, which is generally very wet but may vary greatly from year to year; and a secondary warming immediately after the rainy season. |
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Montreal Protocol |
An international agreement to drastically reduce CFC production, the Protocol was adopted in Montreal in 1987. It was significantly strengthened at a subsequent meeting in London in 1990 that called for a complete elimination of CFCs by the year 2000. The agreement was again amended by a Meeting of the Parties in Copenhagen in November 1992. Consumption of controlled substances--such as CFCs and halons--was greatly reduced or eliminated, and many accountability dates were moved forward, often from 1 January 2000 to 1 January 1996. |
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Mount Pinatubo |
A volcano in the Philippine Islands that erupted in 1991. The eruption of Mount Pinatubo ejected enough particulate and sulfate aerosol matter into the atmosphere to block some of the incoming solar radiation from reaching Earth's atmosphere. This effectively cooled the planet from 1992 to 1994, masking the warming that had been occurring for most of the 1980s and 1990s. |
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mountain and valley breezes |
System of winds that blow downhill during the night (mountain breeze) and uphill during the day (valley breeze). |
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Multi-angle Imaging Spectro-Radiometer (MISR) |
MISR will fly aboard Terra as part of NASA's Earth Observing System. It will monitor the monthly, seasonal, and long-term trends in the amount and type of atmospheric aerosol particles, including those formed by natural sources and by human activities; the amount, types, and heights of clouds; and the distribution of land surface cover, including vegetation canopy structure. See MISR Web Site. |
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Multispectral Scanner (MSS) |
A line-scanning instrument flown on Landsat satellites that continually scans the Earth in a 185 km. (100 nautical miles) swath. On Landsats 1, 2, 4, and 5, the MSS had four spectral bands in the visible and near-infrared with an IFOV of 80 meters. Landsat-3 had a fifth band in the thermal infrared with an IFOV of 240 meters. |
