GEG 111 Topic 4: Earth's Atmosphere — Composition and Structure (Slides 1–8)

Vocabulary flashcards covering key terms related to Earth's atmosphere, its composition, structure, notable gases, atmospheric layers, ozone, aerosols, air pollution, and related environmental policies.

Atmosphere

The gaseous envelope surrounding Earth, composed of permanent and variable gases with water in three phases; the medium for weather and climate.

Meteorology

The science dealing with the atmosphere and its processes, especially as they relate to weather.

Weather

The current conditions of the atmosphere at a location and time, including temperature, humidity, wind, and precipitation.

Climate

The long-term pattern of weather in a region, including averages and variability.

Permanent gases

Gases with long residence times and relatively constant mixing ratios (e.g., N2, O2) in the atmosphere.

Variable gases

Gases whose concentrations vary with time and location, including water vapor, CO2, O3, and CH4.

Water vapor

Water in the gaseous state in the atmosphere; a major variable greenhouse gas essential for weather and cloud formation.

Carbon dioxide (CO2)

A greenhouse gas released by respiration, combustion, and other processes; influenced by natural and human sources; removed mainly by oceans and photosynthesis; winter CO2 tends to be higher due to reduced plant uptake.

Greenhouse gas

A gas that traps heat in the lower atmosphere, contributing to the greenhouse effect and climate warming.

Ozone (O3)

A molecule of three oxygen atoms; in the stratosphere it forms the ozone layer that absorbs UV radiation; at ground level it is a pollutant harmful to health and plants.

Ozonosphere

Another name for the ozone layer in the stratosphere.

Ozone layer

The region of the stratosphere with high ozone concentration that absorbs most of the Sun’s harmful ultraviolet radiation.

Methane (CH4)

A potent greenhouse gas produced by natural and human sources; less publicized than CO2.

Aerosols

Tiny solid or liquid particles suspended in the air (dust, smoke, soot, sea salt, etc.) that affect climate and air quality and can remain aloft for extended periods.

Atom

The fundamental unit of an element; the basic building block of matter.

Molecule

A group of two or more atoms bonded together, forming the smallest unit of a chemical compound.

Air pressure

The force exerted by the weight of the air above a point; decreases with altitude.

Troposphere

The lowest atmospheric layer, containing about 80% of the atmosphere’s mass (weather occurs here)

Stratosphere

Contains the ozone layer; temperature increases with height due to ozone absorption; Layer above the Troposphere

Mesosphere

The atmospheric layer above the stratosphere; temperature generally decreases with height; meteors burn up here.

Thermosphere

The upper atmospheric layer where temperature increases with altitude; very low density; hosts auroras and radio communications; begins around 80 km.

Exosphere

The outermost atmospheric region gradually fading into space; extremely low density; not always considered a distinct layer.

Ionosphere

The electrically charged portion of the upper atmosphere, containing ions and free electrons; enables long-distance radio communication and produces auroras.

Aurora Borealis (N.P)

The northern lights; colorful displays caused by solar particles exciting atmospheric gases in the ionosphere.

Aurora Australis (S.P.)

The southern counterpart to the aurora borealis.

Air pollution

The presence of substances in the air at levels harmful to health, the environment, or materials.

Natural pollution sources

Nonhuman sources of pollutants (e.g., volcanic eruptions like Mt. Pinatubo) and natural aerosols; pollutants can be transported by atmospheric movement.

Anthropogenic pollution

Pollution caused by human activities, such as fossil fuel combustion and industrial processes.

Clean Air Act

U.S. federal law enacted in 1970 to regulate and reduce emissions of air pollutants.

Montreal Protocol

1987 international treaty to phase out ozone-depleting CFCs; 1996 ban by industrialized countries; established a fund to assist developing nations.

Primary pollutants

Pollutants released directly into the air from a source (e.g., CO, NOx, SO2, particulates).

Secondary pollutants

Pollutants formed in the atmosphere by chemical reactions (e.g., ozone, photochemical smog components) rather than being released directly.

Photochemical smog

Smog produced by sunlight-driven reactions between pollutants (NOx and VOCs) that generate ozone and other oxidants.

Consequences of anthropogenic pollutants

Health and environmental impacts such as lung and cardiovascular disease, acid rain, reduced crop yields, forest damage, and soil contamination.

UV index

A scale (EPA and others) indicating the intensity of ultraviolet radiation from the Sun and the potential for skin damage.

Ozone depletion

Reduction of stratospheric ozone concentration caused in part by human-made CFCs and related compounds; addressed by the Montreal Protocol.

UV radiation

Radiation from the Sun in the ultraviolet range (UVA, UVB, UVC) that can cause health effects and is absorbed by the ozone layer.

composition of the Atmosphere:

Oxygen(20.9%), Nitrogen(78%), CO2 (<1%), Argon(.9%)