Surface Winds Winds That Range from 0 to 3,000 Feet in Altitude

Transport

VOCABULARY

Nitrogen Dioxide – Nitrogen oxides, or NOx, sources include: automobiles, trucks and buses, and off-road engines such as aircraft, locomotives, construction equipment, gasoline-powered lawn and garden equipment. Other sources include chemical manufacturers, and combustion sources such as power plants burning fossil fuels.

Ozone – or O3 is a gas composed of three oxygen atoms. "Good" ozone occurs naturally in the stratosphere approximately 10 to 30 miles above the earth's surface and forms a layer that protects life on earth from the sun's harmful rays. In the earth's lower atmosphere, ground level ozone is considered "bad." At ground level, ozone is an air pollutant that damages human health, vegetation, many common materials, and is a key ingredient of smog.

Sunlight/Ultraviolet Radiation - ground level ozone is produced by a photochemical reaction. A photochemical reaction is a chemical reaction that requires light (in this case sunlight) to provide the energy for the reaction. During the summer months, the earth is tilted in such a way that the sun's rays are more direct, and more intense. This combination creates longer and warmer days than in the winter months. Ground level ozone is called the "summertime pollutant" because that is the time of year when the energy from the sun is intense enough to trigger the photochemical reaction necessary to produce ground level ozone from NOx and VOCs.

Surface winds – winds that range from 0 to 3,000 feet in altitude.

Temperature - high temperatures can increase ozone levels by increasing the rate at which the chemical reaction described above occurs.

Transport – surface winds from 1,000 to 3,000 feet that can carry (transport) pollutants far away from the original source.

VOCs – volatile organic compounds, sources include: household products such as paints, paint strippers, and other solvents, wood preservatives, aerosol sprays, cleansers and disinfectants, moth repellents and air fresheners, stored fuels and automotive products, hobby supplies and dry-cleaned clothing. Other sources outside the home include gasoline stations, autobody paint shops, and print shops. In addition to all the man made sources of VOCs, natural sources of VOCs exist. For example, trees naturally release small amounts of VOCs

Wind Direction - NOx can travel large distances before reacting to form ozone. For that reason, it creates regional pollution problems, rather than simply affecting the local area where it is emitted. The action of pollutants traveling distances is called transport. Transported pollutants contribute significantly to the presence of ground level ozone in rural areas.

Wind Speed - Low wind speeds (less than about 10 mph) are necessary for the accumulation of pollutants and subsequent formation of high concentrations of ozone. At speeds above about 10 mph, pollutants are diluted too rapidly for ozone to accumulate significantly.