Glossary - Airborne

A

Absorbent A solid, liquid or gaseous material that takes up another solid, liquid or gas. E.g. Sodium carbonate, sodium bicarbonate, sodium hydroxide, ammonia or limestone used in Flue Gas Desulphurization.

Acid rain Rainwater that has acidity content greater than the postulated natural pH of about 5.6. It is formed when sulfur dioxides and nitrogen oxides, as gases or fine particles in the atmosphere, combine with water vapor and precipitate as sulfuric acid or nitric acid in rain, snow, or fog. The dry forms are acidic gases or particulates. See nitrogen oxides.

Aerosol Particulate matter, solid or liquid, larger than a molecule but small enough to remain suspended in the atmosphere. Natural sources include salt particles from sea spray, dust and clay particles as a result of weathering of rocks, both of which are carried upward by the wind. Aerosols can also originate as a result of human activities and are often considered pollutants. Aerosols are important in the atmosphere as nuclei for the condensation of water droplets and ice crystals, as participants in various chemical cycles, and as absorbers and scatters of solar radiation, thereby influencing the radiation budget of the Earth's climate system. See climate, particulate matter.

Air pollutant See air pollution.

Air pollution One or more chemicals or substances in high enough concentrations in the air to harm humans, other animals, vegetation, or materials. Such chemicals or physical conditions (such as excess heat or noise) are called air pollutants.

Airborne particulates Total suspended particulate matter found in the atmosphere as solid particles or liquid droplets. Chemical composition of particulates varies widely, depending on location and time of year. Airborne particulates include; windblown dust, emissions from industrial processes, smoke from the burning of wood and coal, and motor vehicle or non-road engine exhausts.

Alternative energy Energy derived from nontraditional sources (e.g. solar, hydroelectric, wind).

Ammonium sulfate (NH₄)₂SO₄ The group A white rhombic solid; relative density 1.77; decomposes at 235 C. It is very soluble in water and insoluble in ethanol. It occurs naturally as the mineral mascagnite. Ammonium sulfate was formerly manufactured from the "ammoniacal liquors" produced during coal-gas manufacture but is now produced by the direct reaction between ammonia gas and sulfuric acid. It is decomposed by heating to release ammonia (and ammonium hydrogen sulfate) and eventually water, sulfur dioxide and ammonia. Vast quantities of ammonium sulfate are used as fertilizers.

Ash The mineral content of a product remaining after complete combustion.

Atmosphere The mixture of gases surrounding the Earth. The Earth's atmosphere consists of about 79.1% nitrogen (by volume), 20.9% oxygen, 0.036% carbon dioxide and trace amounts of other gases. The atmosphere can be divided into a number of layers according to its mixing or chemical characteristics, generally determined by its thermal properties (temperature). The layer nearest the Earth is the troposphere, which reaches up to an altitude of about 8 km (about 5 miles) in the polar regions and up to 17 km (nearly 11 miles) above the equator. The stratosphere, which reaches to an altitude of about 50 km (31 miles) lies atop the troposphere. The mesosphere which extends up to 80-90 km is atop the stratosphere, and finally, the thermosphere, or ionosphere, gradually diminishes and forms a fuzzy border with outer space. There is relatively little mixing of gases between layers.

B

Bituminous coal A dense, black, soft coal, often with well-defined bands of bright and dull material. The most common coal, with moisture content usually less than 20 percent. Used for generating electricity, making coke, and space heating. See coal.

British thermal unit (Btu) The quantity of heat required to raise the temperature of one pound of water one degree of Fahrenheit at or near 39.2 degrees Fahrenheit.

C

calcium chloride (CaCl₂) A white deliquescent compound which is soluble in water; relative density 2.15; melting point 782 C; boiling point 1600 C. There are a number of hydrated forms, including the monohydrate, CaCl2.H2O, the dihydrate, CaCl₂.2H₂O (relative density 0.84), and the hexahydrate, CaCl₂.6H₂O (trigonal; r.d. 1.71; the hexahydrate loses 4H2O at 30 C and the remaining 2H₂O at 200 C. ) Large quantities of it are formed as a byproduct of the Solvay process and it can be prepared by dissolving calcium carbonate or calcium oxide in hydrochloric acid. Crystals of the anhydrous salt can only be obtained if the hydrated salt is heated in a stream of hydrogen chloride. Solid calcium chloride is used in mines and on roads to reduce dust problems, whilst the molten salt is the electrolyte in the extraction of calcium. An aqueous solution of calcium chloride is used in refrigeration plants.

calcium oxide (lime) A white solid compound, CaO, formed by heating calcium in oxygen or by the thermal decomposition of calcium carbonate; cubic; relative density 3.35; melting point 2580 C; boiling point 2850 C. On a large scale, calcium carbonate in the form of limestone is heated in a tall tower (lime kiln) to a temperature above 550 C. Although the reaction is reversible, the carbon dioxide is carried away by the upward current through the kiln and all the limestone decomposes. Calcium oxide is used to make calcium hydroxide, as a cheap alkali for treating acid soil, and in extractive metallurgy to produce a slag with the impurities (especially sand) present in metal ores.

capital cost Also known as capital expenditure [CAPEX]. The expenditure by an organization of an appreciable sum for the purchase or improvement of a fixed asset. The amount expended would warrant the item being depreciated over an estimated useful life of a reasonably extended period.

carbon dioxide (CO₂) A colorless, odorless, non-poisonous gas that is a normal part of the ambient air. Carbon dioxide is a product of fossil fuel combustion. Although carbon dioxide does not directly impair human health, it is a greenhouse gas that traps terrestrial (i.e., infrared) radiation and contributes to the potential for global warming. See global warming.

carbon dioxide equivalent (CDE) A metric measure used to compare the emissions from various greenhouse gases based upon their global warming potential (GWP). Carbon dioxide equivalents are commonly expressed as "million metric tons of carbon dioxide equivalents (MMTCDE)." The carbon dioxide equivalent for a gas is derived by multiplying the tons of the gas by the associated GWP.
MMTCDE = (million metric tons of a gas) (GWP of the gas)
See greenhouse gas, global warming potential, carbon equivalent.

carbon equivalent (CE) A metric measure used to compare the emissions of the different greenhouse gases based upon their global warming potential (GWP). Greenhouse gas emissions in the U.S. are most commonly expressed as "million metric tons of carbon equivalents" (MMTCE). Global warming potentials are used to convert greenhouse gases to carbon dioxide equivalents - they can be converted to carbon equivalents by multiplying by 12/44 (the ratio of the molecular weight of carbon to carbon dioxide). The formula for carbon equivalents is:
MMTCE = (million metric tons of a gas) (GWP of the gas) (12/44)
See global warming potential, metric ton, carbon dioxide equivalent.

certified emission reductions A metric measure In the greenhouse gas program, CERs are verified and authenticated reductions of greenhouse gas from the abatement or sequestration projects which are certified by the Clean Development Mechanism.

certified emission reductions In the greenhouse gas program, CERs are verified and authenticated reductions of greenhouse gas from the abatement or sequestration projects which are certified by the Clean Development Mechanism.

chemical reaction Interaction between chemicals in which there is a change in the chemical composition of the elements or compounds involved.

climate The average weather, usually taken over a 30 year time period, for a particular region and time period. Climate is not the same as weather, but rather, it is the average pattern of weather for a particular region. Weather describes the short-term state of the atmosphere. Climatic elements include precipitation, temperature, humidity, sunshine, wind velocity, phenomena such as fog, frost, and hail-storms, and other measures of the weather. See weather.

climate change The term "climate change" is sometimes used to refer to all forms of climatic inconsistency, but because the Earth's climate is never static, the term is more properly used to imply a significant change from one climatic condition to another. In some cases, climate change has been used synonymously with the term, global warming; scientists however, tend to use the term in the wider sense to also include natural changes in climate. See climate, global warming, greenhouse effect, enhanced greenhouse effect.

coal A black or brownish black solid, combustible substance formed by the partial decomposition of vegetable matter without access to air. The rank of coal, which includes anthracite, bituminous coal, subbituminous coal, and lignite, is based on fixed carbon, volatile matter, and heating value. Coal rank indicates the progressive alteration, or coalification, from lignite to anthracite. See anthracite, bituminous coal, lignite.

coal coke A hard, porous product made from baking bituminous coal in ovens at temperatures as high as 2,000 degrees Fahrenheit. It is used both as a fuel and as a reducing agent in smelting iron ore in a blast furnace.

coal gasification Conversion of solid coal to synthetic natural gas (SNG) or a gaseous mixture that can be burned as a fuel.

coal liquefaction Conversion of solid coal to a liquid fuel such as synthetic crude oil or methanol.

coalbed methane Methane that is produced from coal beds in the same manner as natural gas produced from other strata. Methane is the principal component of natural gas.

coal reserves Known coal reserves are spread over 100 countries, estimated to last 200 years [oil & gas reserves are estimated to last approximately 65 years]

cogeneration Production of two useful forms of energy such as high-temperature heat and electricity from the same process. For example, while boiling water to generate electricity, the leftover steam can be sold for industrial processes or space heating.

combustion Chemical oxidation accompanied by the generation of light and heat.

D

Domestic crops Produce from domesticated plants, especially cereals such as wheat, rye and corn. Other examples are soybean, cotton, canola and sugar cane.

E

Emission offset The use of an ERC to offset, or mitigate, an emission increase governed by New Source Review Rules.

Emission Reduction Credit ERCs are reductions in emissions that have been recognized by the relevant local or state government air agency as being real, permanent, surplus, and enforceable. ERCs are usually measured as a weight over time (e.g., pounds per day or tons per year). Such rate-based ERCs can be used to satisfy emission offset requirements of new major sources and new major modifications of existing major sources. Mass-based ERCs, more akin to DERs, are issued with the weight and without reference to time.

EmissionsThe release of a substance (usually a gas when referring to the subject of climate change) into the atmosphere.

Emissions trading Emissions trading is a regulatory program that allows firms the flexibility to select cost-effective solutions to achieve established environmental goals. With emissions trading, firms can meet established emissions goals by: (a) reducing emissions from a discrete emissions unit; (b) reducing emissions from another place within the facility; or (c) securing emission reductions from another facility. Emissions trading encourages compliance and financial managers to pursue cost-effective emission reduction strategies and incentivizes emitting entrepreneurs to develop the means by which emissions can inexpensively be reduced.

Energy conservation Reduction or elimination of unnecessary energy use and waste.

Energy quality Ability of a form of energy to do useful work. High-temperature heat and the chemical energy in fossil fuels and nuclear fuels are concentrated high quality energy. Low-quality energy such as low-temperature heat is dispersed or diluted and cannot do much useful work.

EnergyThe capacity for doing work as measured by the capability of doing work (potential energy) or the conversion of this capability to motion (kinetic energy). Energy has several forms, some of which are easily convertible and can be changed to another form useful for work. Most of the world's convertible energy comes from fossil fuels that are burned to produce heat that is then used as a transfer medium to mechanical or other means in order to accomplish tasks. In the United States, electrical energy is often measured in kilowatt-hours (kWh), while heat energy is often measured in British thermal units (Btu).

F

Fertilizer Substance that adds inorganic or organic plant nutrients to soil and improves its ability to grow crops, trees, or other vegetation.

FlaringThe burning of waste gases through a flare stack or other device before releasing them to the air.

Flue Gas The air coming out of a chimney after combustion in the burner it is venting. It can include nitrogen oxides, carbon oxides, water vapor, sulfur oxides, particles and many chemical pollutants.

Flue Gas Desulfurization The removal of sulfur oxides from exhaust gases of a boiler or industrial process; usually a wet scrubbing operation which concentrates hazardous materials in a slurry, requiring proper disposal.

Fossil fuel A general term for buried combustible geologic deposits of organic materials, formed from decayed plants and animals that have been converted to crude oil, coal, natural gas, or heavy oils by exposure to heat and pressure in the earth's crust over hundreds of millions of years. See coal, natural gas.

Fossil fuel combustionBurning of coal, oil (including gasoline), or natural gas. This burning, usually to generate energy, releases carbon dioxide, as well as combustion by products that can include unburned hydrocarbons, methane, and carbon monoxide. Carbon monoxide, methane, and many of the unburned hydrocarbons slowly oxidize into carbon dioxide in the atmosphere. Common sources of fossil fuel combustion include cars and electric utilities.

Fuel switching A precombustion process whereby a low-sulfur coal is used in place of a higher sulfur coal in a power plant to reduce sulfur dioxide emissions.

G

Glauber’s salt Sodium sulfate decahydrate, Na2SO4.10H2O, used as a laxative. It is named after J.R. Glauber (1604-68).

Granular fertilizers Round, free-flowing pellets sized for application by commercial air-seeders. Airborne's patent protected granular fertilizers are consistent manufacture [2.4 to 4 mm in size, 15% moisture, and density 500 kg/m3], very durable with an indefinite shelf life for shipping/storage.
They are also clean, odor free, dust free, safely handled indoors & outdoors, readily soluble, fast acting & long lasting. They can be easily packaged and enriched with additives & microbes. They are made of fertilizers free of toxic heavy metals [lead, mercury, selenium, etc.].

Greenhouse gas effect In the greenhouse gas program, a concept that refers to the effect that releasing greenhouse gas emissions has on the relative warming of the earth's atmosphere. The release of too much greenhouse gas over a period of time results in a gradual warming of the atmosphere.

Greenhouse gas reduction A greenhouse gas reduction is a reduction in emissions that is recognized to contribute to climate change - e.g. carbon dioxide, methane, nitrous oxide, hydrofluorocarbons, perfluorocarbons, and sulfur hexofluoride. Greenhouse gas reductions are often measured in tons of carbon dioxide-equivalent. For example, 1 ton of methane has the same global warming potential as 20.9 tons of carbon dioxide.

Greenhouse effect The effect produced as greenhouse gases allow incoming solar radiation to pass through the Earth's atmosphere, but prevent part of the outgoing infrared radiation from the Earth's surface and lower atmosphere from escaping into outer space. This process occurs naturally and has kept the Earth's temperature about 59 degrees F warmer than it would otherwise be. Current life on Earth could not be sustained without the natural greenhouse effect.

Greenhouse gas (GHG) Any gas that absorbs infra-red radiation in the atmosphere. Greenhouse gases include water vapor, carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), halogenated fluorocarbons (HCFCs), ozone (O3), perfluorinated carbons (PFCs), and hydrofluorocarbons (HFCs). See carbon dioxide, methane, nitrous oxide, hydrofluorocarbons.

H

Hazardous waste A subset of solid wastes that pose substantial or potential threats to public health or the environment and meet any of the following criteria: it is specifically listed as a hazardous waste by EPA; exhibits one or more of the characteristics of hazardous wastes (ignitability, corrosiveness, reactivity, and/or toxicity); or is generated by the treatment of hazardous waste; or is contained in a hazardous waste.
Heat Form of kinetic energy that flows from one body to another when there is a temperature difference between the two bodies. Heat always flows spontaneously from a hot sample of matter to a colder sample of matter. This is one way to state the second law of thermodynamics.

Heat contentThe amount of heat per unit mass released upon complete combustion.

Heavy metals Metallic elements with high atomic weights, some of which are treated as hazardous waste, e.g., mercury, chromium, cadmium, arsenic, and lead. They can damage living things at low concentrations and tend to accumulate in the food chain.

Higher heating value Quantity of heat liberated by the complete combustion of a unit volume or weight of a fuel assuming that the produced water vapor is completely condensed and the heat is recovered; also known as gross calorific value.

High-sulfur coal See sulfur content.

HydrocarbonsSubstances containing only hydrogen and carbon. Fossil fuels are made up of hydrocarbons. Some hydrocarbon compounds are major air pollutants. See fossil fuel.

I

Interpollutant trading The use of reductions of one type of pollutant to offset the increases of another. For example, SOx is often considered to be a precursor to particulate matter (PM). As such, in some areas SOx reductions can be used to offset PM emission increases (though perhaps at a ratio of greater than 1:1).

J

Joint implementation Agreements made between two or more nations under the auspices of the United Nations Framework Convention on Climate Change to help reduce greenhouse gas emissions.

K

Kyoto ProtocolIn the greenhouse gas program, the Kyoto Protocol is an agreement between 159 nations that attended the 3rd COP to the United Nations Convention on Climate Change which was held in Kyoto, Japan in December of 1997. The Kyoto Protocol specifies the deadlines and specific levels of greenhouse gas reductions that signatory countries are to achieve. Overall, developed countries are to reduce greenhouse gas emissions by 5.2% between 2008 and 2012 as measured against 1990 emission levels.

L

Landfill A method for final disposal of solid waste on land. The refuse is spread and compacted and a cover of soil applied so that effects on the environment (including public health and safety) are minimized. Under current regulations, landfills are required to have liners and leachate treatment systems to prevent contamination of ground water and surface waters. An industrial landfill disposes of non-hazardous industrial wastes. A municipal landfill disposes of domestic waste including garbage, paper, etc. This waste may include toxins that are used in the home, such as insect sprays and powders, engine oil, paints, solvents, and weed killers.

Lignite A brownish-black coal of low rank with high inherent moisture and volatile matter content, used almost exclusively for electric power generation. Also referred to as brown coal.

Low-sulfur coal See sulfur content.

Lower heating value quantity of heat liberated by the complete combustion of a unit volume or weight of a fuel assuming that the produced water remains as a vapor and the heat of the vapor is not recovered; also known as net calorific value.

M

Methane (CH₄) A hydrocarbon that is a greenhouse gas with a global warming potential most recently estimated at 21. 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 petroleum, coal production, and incomplete fossil fuel combustion. The atmospheric concentration of methane as been shown to be increasing at a rate of about 0.6 percent per year and the concentration of about 1.7 per million by volume (ppmv) is more than twice its pre-industrial value. However, the rate of increase of methane in the atmosphere may be stabilizing.

Metric ton Common international measurement for the quantity of greenhouse gas emissions. A metric ton is equal to 2205 lbs or 1.1 short tons.

Mineral Any naturally occurring inorganic substance found in the earth's crust as a crystalline solid.

N

Natural gasUnderground deposits of gases consisting of 50 to 90 percent methane (CH4) and small amounts of heavier gaseous hydrocarbon compounds such as propane (C3H4) and butane (C4H10).

Nitrogen oxides (NOx) Gases consisting of one molecule of nitrogen and varying numbers of oxygen molecules. Nitrogen oxides are produced, for example, by the combustion of fossil fuels in vehicles and electric power plants. In the atmosphere, nitrogen oxides can contribute to formation of photochemical ozone (smog), impair visibility, and have health consequences; they are considered pollutants.

Nitrous oxide (N₂O) A powerful greenhouse gas with a global warming potential most recently evaluated at 310. Major sources of nitrous oxide include soil cultivation practices, especially the use of commercial and organic fertilizers, fossil fuel combustion, nitric acid production, and biomass burning.

NOx allowance An emissions right issued by the governing state participating in the Ozone Transport Commission NOx Budget program that gives authorization to emit one ton of NOx during a specified year pursuant to the rules of the State's NOx Budget program. These Allowances may sometimes be banked into later years.

NOx emissions The sum of nitric oxides and nitrogen dioxides emitted, calculated as nitrogen dioxide.

O

Offset ratio The amount of pollutant that must be secured relative to the on-site emission increase. Often, new sources must offset their emissions at a greater than 1:1 ratio, especially if the offsetting emission reductions are derived from an off-site source.

P

Particulate matter In the New Source Review program, PM represent emissions of any material, except uncombined water, which exists in a finely divided form as a liquid or solid at standard conditions. PM10 is PM emissions with an aerodynamic diameter of 10 microns or less.

Pollution control processes Processes designed to reduce water, noise and air pollution. Waste reduction, energy conservation and safety issues are interrelated and often complimentary to each other. For example, the reduction in the amount of energy a facility consumes usually results in reduced emissions associated with the generation of power.

PotashA potassium chloride compound used as a fertilizer.

Potassium hydroxide(caustic potash; lye) A white deliquescent solid, KOH, often sold as pellets, flakes, or sticks, soluble in water and in ethanol and very slightly soluble in ether; rhombic; relative density 2.044; melting point 360.4 C; boiling point 1320 C. It is prepared industrially by the electrolysis of concentrated potassium chloride solution but it can also be made by heating potassium carbonate or sulfate with slaked lime, Ca(OH)₂. It closely resembles sodium hydroxide but is more soluble and is therefore preferred as an absorber for carbon dioxide and sulfur dioxide. It is also used in the manufacture of soft soap, other potassium salts, and in Ni_Fe and alkaline storage cells. Potassium hydroxide is extremely corrosive to body tissues and especially damaging to the eyes.

R

Regenerate The process of restoring a chemical to its initial state of reaction. E.g. Airborne's restoration of sodium bicarbonate from sodium sulfate after the sodium bicarbonate has reacted with flue gas.

S

Scrubbing A treatment process used to remove gases, toxic and volatile substances from water or air streams. In Flue Gas Desulphurization, large volumes of flue gas are forced through an absorber vessel, or scrubber, to remove (strip out) the dissolved gases and toxic substances before it is exhausted through a flue stack.

Smog Dust, smoke, or chemical fumes that pollute the air and make hazy, unhealthy conditions (literally, the word is a blend of smoke and fog). Automobile, truck, bus, and other vehicle exhausts and particulates are usually trapped close to the ground, obscuring visibility and contributing to a number of respiratory problems.

Sodium-based A class of chemical processes involving the key sodium ion [Na+]. The metal is used as a reducing agent in certain reactions such as Flue Gas Desulphurization. Chemically, it is highly reactive, oxidizing in air and reacting violently with water. Sodium is a major essential element required by living organisms. It is a component of sea salt, sodium chloride [NaCl].

Sodium bicarbonate (NaHCO₃, bicarbonate of soda, baking soda, sodium hydrogencarbonate) A white crystalline solid, soluble in water, relative density 2.159, loses carbon dioxide above 270 C, molecular weight 84. Sodium bicarbonate is also used in bulk for the treatment of acid spillage and in medicinal applications as an antacid. It is also used in baking powders, dry-powder fire extinguishers, and in the textiles, tanning, paper and ceramics industries.

Sodium carbonate (Na₂CO₃, soda ash, sal soda) A white powder, soluble in water, relative density 2.532, loses water at 109 C, melting point 851 C, molecular weight 106. Sodium carbonate is a powerful oxidizing agent and is used in the manufacture of matches and soft explosives, in calico printing, and as a garden weed killer.

Sodium hydroxide (NaOH, caustic soda) A white translucent solid, soluble in water, relative density 2.13, melting point 318 C, boiling point 1390 C, molecular weight 40. Formerly made by the treatment of sodium carbonate with lime but its main source today is from the electrolysis of brine using mercury cells or any of a variety of diaphragm cells. It is strongly alkaline and finds many applications in the chemical industry, particularly in the production of soaps and paper. It is also used to absorb acidic gases, such as carbon dioxide (CO₂) and sulfur dioxide (SO₃), and is used in the treatment of effluent for the removal of heavy metals (as hydroxides) and of acidity. Sodium Hydroxide solutions are extremely corrosive to body tissue and are particularly hazardous to the eyes.

Sodium sulfate (Na₂SO₄) A white crystalline compound, soluble in water, relative density 2.67, melting point 888 C, molecular weight 142. It occurs naturally as mirabilite, threnardite & glauberite. It is produced industrially by the reaction of magnesium sulfate with sodium chloride in solution followed by crystallization, or by the reaction of concentrated sulfuric acid with solid sodium chloride. Sodium sulfate is used in the manufacture of glass, detergent, and soft glazes and in dying to promote an even finish. It also finds medicinal application as a purgative and in commercial aperient salts.

SOx emissions Emissions of sulfur dioxides

Sulfate-based Compounds containing the sulfate ion [SO₄2-]. The ion is absorbed from the soil by plants. Fertilizers containing the sulfate ion are; ammonium sulfate [([NH₄)₂ SO₄] and potassium sulfate [K₂ SO₄].

Sulfur [sulphur] A yellow nonmetallic element occurring in many sulfide and sulphate minerals and native sulfur. Its melting point is 112.8 deg C. Sulfur is an essential element in living organisms and absorbed by plants from the soil as the sulfate ion [SO42-].

Sulfur content The sulfur content of coal in pounds of sulfur per million Btu which can be combined into three ranges for general discussions.

Sulfur [sulphur]

• Low-Sulfur
• 0.41~0.60
• Medium-Sulfur
• 0.61~1.67.
• High-Sulfur
• 1.68~2.50



T

TemperatureMeasure of the average speed of motion of the atoms or molecules in a substance or combination of substances at a given moment. See heat.

U

V

Volatile organic compounds (VOCs) Organic compounds that evaporate readily into the atmosphere at normal temperatures. VOCs contribute significantly to photochemical smog production and certain health problems. /p>

W

Weather Weather is the specific condition of the atmosphere at a particular place and time. It is measured in terms of such things as wind, temperature, humidity, atmospheric pressure, cloudiness, and precipitation. In most places, weather can change from hour-to-hour, day-to-day, and season-to-season. Climate is the average of weather over time and space. A simple way of remembering the difference is that climate is what you expect (e.g. cold winters) and 'weather' is what you get (e.g. a blizzard).



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