Gas Emission Control - Mathematics and Statistics for the Environment - page 449

Density —The weight of a substance per unit of its volume (e.g., pounds per cubic foot).
Dewpoint —The temperature at which a sample of air becomes saturated; that is, it has a rela-
tive humidity of 100%.
Element —Any of more than 100 fundamental substances that consist of atoms of only one
kind and that constitute all matter.
Emission standards —The maximum amount of a specific pollutant permitted to be legally
discharged from a particular source in a given environment.
Emissivity —The relative power of a surface to reradiate solar radiation back into space in the
form of heat, or long-wave infrared radiation.
Energy —The ability to do work, to move matter from place to place, or to change matter from
one form to another.
First law of thermodynamics —Natural law that dictates that during physical or chemical
change energy is neither created not destroyed, but it may be changed in form and moved
from place to place.
Global warming —The increase in global temperature predicted to arise from increased levels
of carbon dioxide, methane, and other greenhouse gases in the atmosphere.
Greenhouse effect —The prevention of the reradiation of heat waves to space by carbon diox-
ide, methane, and other gases in the atmosphere. The greenhouse effect makes possible the
conditions that enable life to exist on Earth.
Insolation —Solar radiation received by the Earth and its atmosphere (incoming solar radiation).
Ion —An atom or radical in solution carrying an integral electrical charge either positive (cat-
ion) or negative (anion).
Lapse rate —The rate of temperature change with altitude. In the troposphere, the normal
lapse rate is -3.5°F per 1000 ft.
Matter —Anything that exists in time, occupies space, and has mass.
Mesosphere —A region of the atmosphere based on temperature that is between approxi-
mately 35 to 60 miles in altitude.
Meteorology —The study of atmospheric phenomena.
Mixture —Two or more elements, compounds, or both, mixed together with no chemical reac-
tion occurring.
Ozone —The compound O 3 . It is found naturally in the atmosphere in the ozonosphere and is
also a constituent of photochemical smog.
pH —A means of expressing hydrogen ion concentration in terms of the powers of 10; mea-
surement of how acidic or basic a substance is. The pH scale runs from 0 (most acidic) to
14 (most basic). The center of the range (7) indicates the substance is neutral.
Photochemical smog —An atmospheric haze that occurs above industrial sites and urban
areas resulting from reactions, which take place in the presence of sunlight, between pol-
lutants produced in high temperature and pressurized combustion processes (such as the
combustion of fuel in a motor vehicle). The primary component of smog is ozone.
Photosynthesis —The process of using the sun's light energy by chlorophyll-containing plants
to convert carbon dioxide (CO 2 ) and water (H 2 O) into complex chemical bonds forming
simple carbohydrates such as glucose and fructose.
Pollutant —A contaminant at a concentration high enough to endanger the environment.
Pressure —The force pushing on a unit area. Normally, in air applications, pressure is mea-
sured in atmospheres (atm), Pascals (Pa), or pounds per square inch (psi).
Primary pollutants —Pollutants that are emitted directly into the atmosphere where they exert
an adverse influence on human health or the environment. The six primary pollutants are
carbon dioxide, carbon monoxide, sulfur oxides, nitrogen oxides, hydrocarbons, and par-
ticulates. All but carbon dioxide are regulated in the United States.
Radon —A naturally occurring radioactive gas arising from the decay of uranium 238, which
may be harmful to human health in high concentrations.