T
Tectonic Activity - The process of the formation, movement, interaction, and destruction of parts of the earth's crust on a generally large scale. This can be used to explain seismicity, volcanism, and mountain building. [Geology; v21; 2127-30; 1993.] [Journal of Oil and Gas; v92; 86-93; 1994.] [Science; v277; 1177; 1997.] [Science; v310; 1914 - 1915; 2005.]
Tectonics - The structural arrangement of rocks in any crust of a planet. Used to understand rock structures. [Energy; v18; 1263-71; 1994.] [Science; v263; 1593-60; 1994.] [Science; v315; 1650-1651; 2007.]
Temperature Inversion - The abnormal reversal of temperature in the troposphere caused meteorological conditions. This leads to the entrapment of urban air pollution because mixing of surface air into the rest of the troposphere is limited. Under normal circumstances, air in the troposphere is cold at high altitudes and warm at low altitudes, or near the earth's surface. When air pollutants, such as SO2 or NOx, in urban areas get too concentrated, smog is produced. Since cold air underlies the warmer air at high altitudes, the air does not mix well which can lead to human health disturbances in people with respiratory illnesses such as asthma. Surface temperature inversions are created when the lapse rate goes negative, that is, when the temperature profile of low lying tropospheric air increases with altitude. Air at the earth's surface is trapped there because the air above it is less warmer and less dense. This can be disastrous for the air quality in urban areas when anthropogenic pollutants are not mixed away from the surface and, instead, build up. In London, England in 1952, 4,000 people died during a 4 day temperature inversion event in December. [Alden, Robert. "1948 Donora Smog Killed 20; London Toll Was 4,000 in '52." New York Times 26 Nov. 1966: 28.] [Atmospheric Environment; v35; 2417-2421; 2001.] [Atmospheric Environment; v41; 327-338; 2007.]
Termolecular Reaction - A reaction containing three particles. In the atmosphere an example of a termolecular reaction is one in which a molecule acquires the excess energy released by a reaction so that the products created do not convert back to the original state of the reactants. The reaction of molecular oxygen with an oxygen atom (radical) to produce ozone is a good example of an important atmospheric termolecular reaction. In the atmosphere this third body is most often molecular nitrogen because statistically this is the most likely next collision since atmospheric N2 = 78% by volume. [Analytical Chemistry; v27; 2021-24; 1994.] [Analytical Chemistry; v64; 1273-80; 1994.] [Journal of the American Society for Mass Spectrometry; v17; 544-561; 2006.]
Terpene - A naturally occurring organic compound, of the general empirical formula, C10H16, biologically built from a naturally occurring "monomer" called isoprene, C5H8, which is found as a volatile oil in plants. A clearly important--and olfactorily obvious--example is alpha-terpinene found in lemon oil. [Analytical Chemistry; v65; 2528-33; 1993.] [Food Technology; v48; 110-12; 1994.] [Analytica Chimica Acta; v559; 97-104; 2006.]
tert Butyl Alcohol - (t-butanol) A highly flammable, volatile, colorless liquid which has a camphor-like odor. It is miscible in esters, and aromatic and aliphatic hydrocarbons, and soluble in water. Based on its vapor pressure, tert-butyl alcohol will exist mainly in the vapor phase in the atmosphere. It is most likely to react with the hydroxyl (OH) radical at this state. The reaction products are formaldehyde and acetone. One of MTBE's atmospheric decomposition products is t-butanol. [Chemosphere; v53; 469-477; 2003.]
Tertiary Period - This extended from about 65 million years ago to about 2.5 million years ago. [Atmospheric Change: An Earth System Perspective; p.13; 1993.] [Journal of Geochemical Exploration; v90; 24-44; 2006.]
Tetrachloroethane - No longer intentionally produced by industrial plants in the United States as an end product. In the past it was often used as a solvent and was a component found in several pesticides. There are several health hazards associated with short term and long term exposure. Long term exposure leads to damage of the central nervous system and liver. It is a colorless liquid that has a sweet chloroform odor, has a molecular weight of 167.85 g/mol, melting point of -43.8 degrees C, and is a corrosive liquid. [Environmental Pollution; v101; 221-230; 1998.]
Tetrachlorethylene - This is used as a industrial cleaner. One of the most abundant pollutants in water pollution. This chemical degrades and can produce vinyl chloride which is a carcinogenic to humans. [Journal of Environmental Engineering and Science; v4; 11-15; 2005.]
Tetrachloromethylene - This compound, also called perchloroethylene, is used for dry cleaning purposes; often it is recycled by the cleaners for reuse. [Water Research; v36; 1902-1908; 2002.]
Tetradecane - A light, oily hydrocarbon with a melting point of 5.89 degrees C and a boiling point of 253.7C. As a gas-phase pollutant it is inactive as a human contact allergen. [Environmental Health Perspectives v. 105, September 1997, p. 986-992.] [Journal of Hazardous Materials; v40; 213-235; 1995.]
Tetraethyl lead (TEL) - C8H20Pb, an organometallic used as a gasoline additive that prevents engine knocking. Leaded fuel allows for better efficiency, but the lead released in car emissions, as lead oxides, is very toxic to humans. Lead would get deposited on the road and get washed away into drinking water. [Analytical Chemistry; v68; p3008-3014; 1996.] [Atmospheric Environment; v37; 3077-3089; 2003.]
Thermal-IR Radiation - Long wavelength solar radiation from the sun bounces off the Earth's surface as it is reflected back up in the troposphere. In addition, shorter wavelengths of light are absorbed by the earth's surface and reradiated to space in the IR. Thermal IR, and all IR is invisible to the eye but can be felt with the skin. [Remote Sensing of Environment; v107; 3; 2007.]
1,2,4,5-Tetramethylbenzene - chemical used in polyamide resin, plasticizer, and as an aromatic additive in gasoline. At room temperature it is a white, crystalline powder, an aromatic, with a molecular weight of 134.21. [Solid State Nuclear Magnetic Resonance, v13; 137-148; 1998.] [Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy; v63; 766-773; 2006.]
Thermodynamics - The science of heat and temperature and of the laws governing the conversion of heat into mechanical, electrical, or chemical energy. [Crutzen, Paul J. and Graedel, T.E. Atmospheric Change: An Earth System Perspective. Freeman Press; 1993; p. 436.]
Thermosphere - The outermost shell of the atmosphere, between the mesosphere and outer space; where temperatures increase steadily with altitude.
Toluene - a highly volatile and water-soluble benzene derivative that is highly toxic to most forms of life. Its estimated lifespan in air is 60 hours in the case of a photochemical reaction with hydroxyl radical and is eventually oxidized to carbon dioxide. Toluene is used in a variety of industries including the manufacture of TNT, pharmaceuticals, rubbers, and other benzene derivatives, and is also a fuel additive and a paint solvent. Toluene also reaches the atmosphere from natural sources such as coal tar, mineral oils, and forest fires.
TOMS (Total Ozone Mapping Spectrometer) - An instrument that measures the total ozone in a vertical column of atmosphere. Measurements are made by comparing the amount of backscattered ultraviolet radiation with the amount of incoming solar energy. These changes in this ratio, the earth's albedo, at specific wavelengths can be used to determine the amount of ozone present. Four satellites create global maps daily of the earth's ozone measurements. [Ozone Science and Engineering; v24i6; page399; 2002] [Atmospheric Environment; v34I17; pages 2681-2690; 2000]
Total Column Ozone - The total amount of ozone that is found in a column of air above the earth from the surface to the top of the atmosphere. The majority of this amount is typically found in the stratosphere. [Journal of Geophysical Research; v 95; 13883; 1990]
Trace Gases - These are gases in the atmosphere that do not occur in large quantities but are significant to life on Earth or are important constituents of the chemical cycles in the atmosphere. [Journal of American Hygienist Association; v54; 639-46; 1993.] [Atmospheric Environment B; v27B; 275-82; 1993.]
Trade Winds - Wind systems occupying most of the tropics, which blow from 30 degrees North and South toward the equator; winds are northeasterly in the Northern Hemisphere and southeasterly in the Southern Hemisphere. [An Introduction to the World's Oceans; 5th edition; p493; 1997.]
Trajectory - The curve or a path that an object makes while in space. Trajectory is usually a set of points on the path taken [ActaEntomologica Sinica. v47; 599-606; 2004.]
Trichloroethylene (TCE) - C2HCl3, this is an industrial solvent used primarily for vapor degreasing and cold cleaning. It is an extraction solvent for greases, oils, fats, waxes, and tars, and is used by the textile processing industry to sour cotton, wool, and other fabrics. Exposure to moderate amounts of trichloroethylene may cause various health effects such as headaches, vertigo, visual disturbance, tremors, and dizziness. Death may occur from inhalation of large amounts. People located near or downwind of sites where TCE may be in operation might be exposed to higher levels. It is a carcinogen. [Journal of Environmental Management; v83; 56-65; 2007.] [Journal of Molecular Catalysis A: Chemical; v217; 109-115; 2004.]
Trichlorofluoromethane (Freon®-11) - One of the principal greenhouse
gases, a gas with absorption bands in the infrared portion of the spectrum.
There is extensive evidence showing that a class of synthetic
compounds, the chlorofluorocarbons (CFCs), are responsible for the
destruction of the ozone layer. CFCs are molecules that contain one or more
atoms of both chlorine and fluorine. In September of 2004, the ozone hole
over Antarctica was the largest area ever recorded and was almost THREE times
larger than the area of the
Tropopause - The area where the temperature in the troposphere no longer decreases, indicating the boundary between the troposphere and the stratosphere. [Atmospheric Environment; v28; no1; 53-68; 1994.] [Journal of Atmospheric Science; v51; 509-29; 1994.]
Troposphere - The lowest layer of the Earth's atmosphere, ranging from the ground to the base of the stratosphere with a altitude of 10-15 kilometers depending on the latitude. This is where all weather occurs. The word troposphere is derived from the Greek words tropos--turning and spharia--sphere. [Science of The Total Environment; v374; 135-142; 2007.] [Journal of Atmospheric and Solar-Terrestrial Physics; v68; 523-538; 2006.]
U
UARS (Upper Atmosphere Research Satellite) - A satellite deployed by NASA to study the chemistry in the upper atmosphere of Earth. [Chemical and Engineering News; v70; 27-8; 1990.] [Manufacturing Systems; v8; 36-8; 1990.]
Ultraviolet Light - See UV-A, UV-B, and UV-C.
Umbra - During a solar eclipse the moon completely blocks the sun from shining on the Earth. In the umbra, the source of light is completely blocked by the moon causing the shadow on the Earth. [Vistas in Astronomy; v14; 1-11; 1972.] [Physics of The Earth and Planetary Interiors; v4; 197-198; 1971.]
Unleaded Gasoline - This fuel consists mostly of hydrocarbons and is sometimes enhanced with benzene to increase octane ratings and is used as fuel in internal combustion engines. Unleaded gasoline is manufactured to meet the requirement of new model automobiles in the US since 1975, because in that year catalytic converters were made mandatory for all vehicles sold in the US. Lead was removed from gasoline because lead emissions poison the metals used in catalytic converters. Lead had been added to gasoline since the 1920's as tetraethyllead (TEL), historically referred to as "ethyl." Exposure to high levels of lead can cause vomiting, diarrhea, convulsions, coma or even death, but lead emissions from automobiles consisted of lead oxide particles which settle out near highways. Lead removal from gasoline in the US has resulted in a clear, measurable decrease in lead in the urban environments in the US. [Fuel and Energy Abstracts; v47; 5; 2006.] [Applied Thermal Engineering; v27; 358-368; 2007.]
Uranium-Thorium Dating - An absolute dating technique which uses the properties of the radioactive half-life of Uranium-238 and Thorium-230. The half-life of uranium-238 is 4.5 billion years, that is, in that many years half of the original amount is still uranium-238 while the other half has lost nucleons to form a different element which is more stable. [Quaternary Geochronology; v1; 289-295; 2006.]
Urban Air Pollution - Pollution that occurs in cities from the burning of fossil fuels and the emissions of hydrocarbons. Urban air pollution can be in the form of ozone, smog, acid rain, carbon monoxide, particulate matter (PM-10), and nitrogen oxides. [Journal of Environmental Management; v84; 27-37; 2007.] [Toxicology Letters; v168; 200-209; 2007.]
Urban Heat Island Effect - Urban heat island effect is the condition in which a city is relatively warmer than the surrounding areas due to the heat generated by the good conductors such as concrete, cars, and city buildings and the lack of vegetation. [Journal of Applied Meteorology, v7; 575-582; 1968.] [Renewable Energy; v32; 1805-1816; 2007.] [Remote Sensing of Environment; v106; 375-386; 2007.]
UV-A - Ultraviolet light that has wavelengths of 320 nm to 400 nm.
The wavelengths of this light are shorter than visible light and are not absorbed
in the stratosphere by ozone. [
UV-B - An ultraviolet wavelength of light between 280 nm and 320 nm whose intensity is increasing at the earth's surface (probably causing increases in skin cancer), This UV increase is because of decreases in stratospheric ozone. [Research and Development Magazine; v39; 18LS; 1997.] [Chemical and Engineering News; v71; 12-13; 1993.]
UV-C - Light that spans the spectrum with wavelengths of 10 nm to 290 nm. These wavelengths of ultraviolet light are extremely dangerous to human and animal tissue and is totally absorbed in the stratosphere by ozone and molecular oxygen. [Environmental and Experimental Botany, v. 45, 1-9; 2001]
UV/Vis Spectrophotometry - Ultraviolet/visible spectrophotometry is used to measure the absorption capabilities of certain compounds with reference to wavelengths of light on the ultraviolet and visible light ranges. [Skoog, West, and Holler; Fundamentals of Analytical Chemistry. 7th ed. pg. 57-58; 1996.] [Journal of Photochemistry and Photobiology A: Chemistry; v187; 1-9; 2007.] [Atmospheric Environment; v29; 3239-3243; 1995.]
UV Radiation- energy that is emitted in the form of electromagnetic waves with a wavelength of 1-380nm, which is composed of UV-A, UV-B, and UV-C light; UV-A light being the longest wavelength and having the smallest energy and UV-C light being the shortest wavelength and having the highest energy. All UV-C light and most UV-B light is filtered out of the atmosphere via the ozone layer. However, UV-A light travels to the surface of the earth. [Environmental Pollution; v88n2; 219; 1995.] [Journal of Photochemistry and Photobiology B: Biology; v46; 5-19; 1998.] [Journal of Atmospheric and Solar-Terrestrial Physics; v67; 1321-1330; 2005.]
V
Vadose Zone- The unsaturated zone in a soil
where chemical processes are at their most active. Its extent is determined partly by the content of the
soil water, but it cannot extend beyond the water table, below which voids are
completely filled with water. [The
Valence Electrons - The outermost electrons of an atom that are in the orbitals of highest principal quantum number of all electrons in the atom and don't fill that orbital completely. [Physics Chemistry; v100; 5715-20; 1986.] [Organic Chemistry; 2nd ed; 48-50; 1997.]
Vapor ‚ A substance in the gas state that is below its critical temperature but still suspended in air. It is possible for a vapor to be liquefied by increased pressure. Vapors are usually not visible. [Environmental Pollution; v123; 413-425; 2003.] [Atmospheric Environment; v37; 1223-1230; 2003.]
Venus - Second planet
from the sun; mass 4.872 x 1027g; radius of cloud surface about
6100 Km; radius of solid surface about 6056 Km; surface temperature 737K;
temperature of cloud tops 250K; cloud composition more than 75% H2SO4
and about 25% water; atmosphere (by volume) 90-95% CO2 with traces
of SO2, water, CO, H2SO4, Ar,
Ne, HF, HCl. Atmospheric pressure 92-95 atm.
[Hopkins, Jeanne. Glossary of Astronomy and Astrophysics.
pg 187; 1980;
Vernal Equinox - A time during the spring season when the sun is directly above the equator which results in an equal amount of time for day and night. [Journal of Applied Meteorology; v30n4; 494; 1991.] [Journal of Atmospheric and Terrestrial Physics; v51n2; 111; 1989.]
Vertical Flux - In dry deposition this refers to the rate at which a gas particle is deposited onto another surface without the aid of precipitation. Vertical flux equals concentration of the species multiplied by the deposition velocity. [International Journal of Heat and Mass Transfer; v31n11; 2291; 1988.] [Journal of Atmospheric Sciences; v48n11; 1909; 1991.]
Vertical Mixing - The movement of air in a vertical direction usually caused by differences in temperature and density. [Atmospheric Environment; v26n6; 965; 1992.] [Journal of Geophysical Research; v99; 20345; 1994.]
Vinyl Bromide - a toxic compound that was established as a federal hazardous air pollutant in 1993. Sources of vinyl bromide may include rubber substitution, flame-retarding treatment of acrylics, laminating, and/or preparing films. It is also important to point out that vinyl bromide may be the result of the atmospheric degradation of 1,2-dibromoethane. Based on a typical atmospheric gas phase reaction with a hydroxyl radical, the lifetime of vinyl bromide in the atmosphere is between 1.5 and 2.1 days resulting in the products formaldehyde and formyl bromide.[Experimental and Molecular Pathology, v28; 25-33; 1978.] [Environmental Science Technology; 41; 1352-1358; 2007.] [Journal of Physical Chemistry A.; 105; 1830-1837; 2001.]
Vinyl Chloride - [CAS# 75-01-4] Chemical Formula C2H3Cl: Synonyms: Ethylene, chloro-; Chloroethene; Chloroethylene; Monochloroethylene; Vinyl chloride; Vinyl chloride monomer; Vinyl C monomer; C2H3Cl; Ethylene monochloride; Monochloroethene; Chlorethene; Chlorethylene; Chlorure de vinyle; Cloruro di vinile; Rcra waste number U043; Trovidur; UN 1086; VC; VCM; Vinile; Vinylchlorid; Vinyl chloride, inhibited; Vinyle(chlorure de); Winylu chlorek. This colorless gas is used mainly to produce polyvinylchloride. As there are no natural sources known for this compound, all sources are anthropogenic. The compound reacts with hydroxyl radicals in the atmosphere to yield chlorine radicals, which catalytically destroy ozone. [Water Research; v35; 561-566; 2001.] [Atmospheric Environment; v30; 751-756; 1996.]
Visibility - A measurement of the ability to see and identify objects at different distances. [Measurement Science and Technology; v5n12; 1505; 1994.] [Atmospheric Environment; v28n20; 3277; 1994.] [Atmospheric Environment; v40; 593-605; 2006.]
Volcanoes - Openings in the earth's crust that release molten rock, steam, reduced and oxidized compounds, and ash from within the earth's interior into the atmosphere. [Earth in Space; v4n3; 5; 1991.] [Icarus; v81n2; 298; 1989.]
W-Z
Walker Cell - A zonal circulation of the atmosphere confined to equatorial regions and driven principally by the oceanic temperature gradient. In the Pacific, air flows westward from the colder, eastern area to the warm, western ocean, where it acquires warmth and moisture and subsequently rises. A return flow aloft and subsidence over the eastern ocean complete the cell.
Water - Water consists of two hydrogen atom and one oxygen atom (H2O). Water covers three-fourths of the Earth's surface, 60-70% of the world's weight, regenerates and redistributes through evaporation and other atmospheric processes. Water is involved in electrical charge separation because it has two types and positions of atoms giving it a net dipole movement. Water vapor also absorbs 17% of solar radiation in the troposphere, thus making it one of the two principal greenhouse gases. Of the solar energy absorbed by the Earth's surface a little more than half goes into latent heat, which is heat absorbed by water because of its transformation from a liquid to a gas. When these molecules condense back into a liquid, usually higher in the atmosphere, they released that energy back into the atmosphere as local warming.
Water Cycle- The process by which water is transpired and evaporated from the land and water, condensed in the clouds, and precipitated out onto the earth once again to replenish the water in the bodies of water on the earth.
Water Vapor - Water present in the atmosphere in gaseous form; the source of all forms of condensation and precipitation. Water vapor, clouds, and carbon dioxide are the main atmospheric components in the exchange of terrestrial radiation in the troposphere, serving as a regulator of planetary temperatures via the greenhouse effect. Approximately 50 percent of the atmosphere's moisture lies within about 1.84 km of the earth's surface, and only a minute fraction of the total occurs above the tropopause.
Weak Sun Paradox - This refers to the fact that our sun has probably increased its luminosity during its lifetime (approximately 3.5 billion years). This assumption is based on astrophysical observations of many other stars. The best scientific conclusions are that when our sun was young it had a luminosity (total energy output) of 70-80% of what it is today; however, there has clearly been (based on geological records and long term evidence for the presence of liquid water) approximately the SAME long term planetary temperature on earth (about 15 degrees C, averaged planet-wide) instead of colder earlier surface temperatures followed later by warmer surface temperatures. This paradox suggests that the planet's surface temperature may have been controlled by atmospheric gases whose concentrations varied over time while keeping (via the greenhouse effect) the surface temperature relatively constant (see Gaia hypothesis). [Science; v33n6; 20; 1993.] [The Atmospheric Journal; v98n6; 2268; 1989.] [Science, v177, 52-56; 1972.]
Wien's Displacement Law - The relationship between wavelength and temperature in relation
to blackbody radiation. The wavelength decreases as the temperature
increases. The common formula to determine this relationship is Plank's Formula.
[Eisberg, R & Resnick,
R. "Thermal Radiation." in Quantum Physics of Atoms, Molecules,
Solids, Nuclei, & Particles. 2nd ed.
Wind Energy - Using the wind to turn a windmill blade to generate electricity. The blades collect the wind's energy as it goes over the blades because they slow down the speed of the wind; the blades are spun and the wind is slowed. The blades are connected to a drive shaft which is turning an electric generator to produce electricity. [Energy Economics; v1; 1; 2007.] [Renewable Energy; v32; 2242-2246; 2007.]
Wind Rose - A diagram that presents information about wind speed and direction for a particular area over a certain amount of time. The diagram is a circle with spokes. The center is 0 and as the wind frequency increases bars extend from the center of the circle to the outside of the circle, in the direction the wind is blowing. Direction can be determined by which way the bar is extending to the outside of the circle because the wind rose is set up like a compass. Information for a windrose is gathered by monitoring stations throughout the area being monitored. By determining wind speed, direction, and frequency with a wind rose, movement of air, and pollutants can be predicted. [Atmospheric Environment; v40; 7480-7493; 2006.] [Cold Regions Science and Technology; v47;171-179; 2007.]
Wet Deposition - The deposition of dissolved substances such as airborne particles and gaseous molecules by precipitation. Airborne particles/gaseous molecules in the atmosphere are trapped in water droplets due to falling precipitation (i.e. rain and snow). These substances are then dissolve in the water droplets and are deposited on the surface in which the water droplets come into contact with. [Environmental Science Technology; v34; 4294; 2000] [Environmental Science Technology; v34; 361; 2000] [Atmospheric Environment; v40; 5893-5901; 2006.]
Xylene - An aromatic hydrocarbon used as a common industrial solvent, also named dimethylbenzene; exists as 3 isomers: m-xylene, o-xylene, and p-xylene. Xylene is usually obtained from petroleum and natural gas distillates. It is used in paint, rubber and leather industries, and also as a cleaning agent or degreaser. [Atmospheric Environment, v. 33, Issue 7, 1085-1092; 1999.] [Toxicology; v231; 147-158; 2007.]
Younger Dryas Period - A transition from the last glacial period, to the present interglacial period punctured by a brief and intense return to cold conditions around 10,900 years ago. Scientists believe this occurred because of the changes in atmospheric circulation resulting from large releases of melt water from glaciers. [Quaternary Science Reviews; v25; 3-4; 2006.] [Science; v315; 439; 2007.] [Palaeogeography, Palaeoclimatology, Palaeoecology; v246; 307-330; 2007.]
Zeolite - Microporus silicate or aluminosilicate structured minerals that can act as an absorbing filter or sieve on a molecular level. Mainly used by the petroleum industry for the cracking of petroleum or use as a filter against various compounds. [Journal of Physical Chemistry; v100; 1814-19; 1996.] [Water Environment and Technology; v8; 14; 1996.] [Catalysis Communications; v8; 539-542; 2007.]