APES Withgott & Laposata Chapter 17 Atmospheric Science, Air Quality & Pollution Control

Atmosphere

A layer of gases that may surround the Earth and other material bodies of sufficient mass.

Troposphere

A layer of the atmosphere closest to the surface of Earth, extending up to approximately 16 km (10 miles) and containing most of the atmosphere's nitrogen, oxygen, and water vapor.

Stratosphere

2nd layer of atmosphere; extends from 10 to 30 miles up; location of ozone layer; absorbs 95% of Ultraviolet radiation; temperature increases, oxygen levels decrease with altitude increase.

Ozone layer

Layer of the stratosphere with a high concentration of ozone; absorbs most of the Sun's harmful ultraviolet radiation.

Atmospheric Pressure

The pressure exerted by the weight of the atmosphere above the point of measurement.

Relative humidity

The amount of water vapor in the air at any given time is usually less than that required to saturate the air. Expressed as a percentage.

Convective circulation

Less dense warm air rises and creates vertical currents- as it rises into areas of lower atmospheric pressure it expands and cools, once it cools it descends and becomes denser and replaces the rising warm air.

Climate

Seasonal pattern of weather conditions in an area over many years; does not change rapidly.

Weather

Conditions in the atmosphere closest to the Earth's surface, such as wind and precipitation.

Warm Front

A front where warm air moves over cold air and brings drizzly rain and then are followed by warm and clear weather.

Cold Front

A weather front in which a cold air mass moves into and under a warm air mass. It creates a narrow band of intense precipitation.

High-pressure system

Formed when an air mass cools over an ocean or a cold region on land. This dense system moves outward toward low pressure systems, creating a wind. Causes, clear blue skies, is dry etc.

Low-pressure system

An air mass in which the air moves toward the low atmospheric pressure at the center of the system and spirals upward, typically bringing clouds and precipitation.

Temperature inversion

A deviation from the normal temperature distribution in the atmosphere, resulting in a layer of cold air temporarily trapped near the ground by a warmer, upper layer.

Ferrel Cells

Atmospheric cells that circulate between about 30 degrees and 60 degrees north and south latitudes.

Polar Cells

Where polar air sinks and flows away from the poles downward, meeting the ferrel cells at 60 degrees latitude

Coriolis effect

Causes moving air and water to turn left in the southern hemisphere and turn right in the northern hemisphere due to Earth's hemisphere.

Air pollutants

Gases and particulate material added to the atmosphere that can affect climate or harm people or other organisms.

Air pollution

Concentration of trace substances such as carbon monoxide, sulfur oxide, hydrocarbons, and solid particulates, at a greater level than occurs in average air.

Primary pollutants

Pollutants that are put directly into the air by human or natural activity.

Secondary pollutants

Pollutants that form from chemical reactions that occur when primary pollutants come in contact with other primary pollutants or with naturally occuring substances, such as water vapor.

Criteria Pollutants

The 1970 amendments to the Clean Air Act required EPA to set National Ambient Air Quality Standards for certain pollutants known to be hazardous to human health. EPA has identified six criteria pollutants: sulfur dioxide, carbon monoxide, lead, nitrogen oxides, ozone, and particulate matter.

Volatile organic compunds

Organic chemicals and petrochemicals that emit vapors while evaporating. In paints, VOC generally refers to the solvent portion of the paint which, when it evaporates, results in the formation of paint film on the substrate to which it was applied.

Toxic Air Pollutants

Substances known to cause cancer, reproductive defects, or neurological, developmental, immune system, or respiratory problems that are present in air pollution.

Industrial smog

Type of air pollution consisting mostly of a mixture of sulfur dioxide, suspended droplets of sulfuric acid formed from some of the sulfur dioxide, and a variety of suspended solid particles. Compare photochemical smog.

Photochemical smog

A brownish haze that is a mixture of ozone and other chemicals, formed when pollutants react with each other in the presence of sunlight.

CFCs

Chlorofluorocarbons. Man made chemicals used as coolants and propellants in aerosols. Potent greenhouse gases that also lead to depletion of the ozone layer.

Montreal Protocol

1987 meeting in Montreal to develop the treaty to cut emissions of CFCs in the atmosphere.

Acidic deposition

The settling of acidic or acid-forming pollutants from the atmosphere onto Earth's surface. This can take place by precipitation, fog, gases, or the deposition of dry particles.

Atmospheric deposition

The movement of particulate and dissolved matter from the atmosphere to Earth's surface by gravity or in precipitation.

residence time

the time a pollutant stays in the atmosphere

Clean Air Act

(CAA, 1970) set emission standards for cars and limits for release of air pollutants

scrubbers

chemically convert or physically remove airborne pollutants before they are emitted from smokestacks have allowed factories, power plants, and refineries to reduce emissions of several pollutants

NAAQS

National Ambient Air Quality Standards

tropospheric ozone

ozone that is located in the troposphere (the layer of the atmosphere nearest the Earth's surface) and plays a significant role in the greenhouse gas effect and urban smog.

ozone-depleting substances

Any compound that contributes to stratospheric ozone depletion .

chlorofluorocarbons

gases containing chlorine and fluorine, formerly used in air conditioners, refrigerators, and spray cans. They are ozone-depleting substances.

formaldehyde

An air pollutant that is a colorless chemical used to manufacture building materials and many household products, such as particleboard, hardwood plywood paneling, and urea-formaldehyde foam insulation.

sick-building syndrome

A set of symptoms, such as headaches, fatigue, eye irritation, and dizziness, that may affect workers in modern, airtight office buildings; believed to be caused in indoor pollutants