Environmental Engineering Reference
In-Depth Information
Anaerobic decomposition:
Decomposition in the absence of oxygen, as in an anaer-
obic digester or a lagoon; it produces carbon dioxide and methane.
Anaerobic digestion:
A biochemical process by which organic matter is decom-
posed by bacteria in the absence of oxygen, producing methane and other
byproducts.
Anaerobic lagoon:
A liquid-based organic waste management installation charac-
terized by waste residing in water at a depth of at least 6 feet for periods of
30 to 200 days.
Anemometer:
Wind speed measurement device used to send data to a controller.
Also used to conduct wind site surveys.
Angle of attack:
In wind turbine operation, the angle of the airflow relative to the
blade.
Angle of incidence:
The angle that a ray of sun makes with a line perpendicular to
the surface. For example, a surface that directly faces the sun has a solar
angle of incidence of zero, but if the surface is parallel to the sun (for exam-
ple, sunrise striking a horizontal rooftop), the angle of incidence is 90°.
Anion:
A negatively charged ion; an ion that is attracted to the anode.
Annual fuel utilization efficiency (AFUE):
A measure of space heating equipment
efficiency defined as the fraction of energy output/energy input.
Annual removals:
The net volume of growing stock trees removed from the inven-
tory during a specified year by harvesting, cultural operations such as tim-
ber land improvement, or land clearing.
Annualized growth rate:
Calculated as (
x
n
/
x
1
)
1/
n
, where
x
is the value under consid-
eration and
n
is the number of periods.
Anode:
The electrode at which oxidation (a loss of electrons) takes place. For fuel
cells and other galvanic cells, the anode is the negative terminal; for elec-
trolytic cells, the anode is the positive terminal.
Anthropogenic:
Made or generated by a human or caused by human activity. The
term is used in the context of global climate change to refer to gaseous
emissions that are the result of human activities, as well as other potentially
climate-altering activities, such as deforestation.
Anuran:
Of or relating to frogs and toads.
API gravity:
American Petroleum Institute measure of specific gravity of crude
oil or condensate in degrees; an arbitrary scale expressing the gravity of
density of liquid petroleum products. The measuring scale is calibrated in
terms of degrees API; it is calculated as follows:
Degrees API = (141.5/Sp. Gr. @ 60°F/60°F) - 131.5
Apparent power:
The product of the voltage (in volts) and the current (in amperes).
It is comprised of both active and reactive power. It is measured in volt-
amperes and often expressed in kilovolt-amperes (kVA) or megavolt-
a m p e r e s ( M VA).
Appropriate use:
A proposed or existing use on a refuge that meets at least one of
the following conditions: (1) the use is a wildlife-dependent one, or (2) the
use contributes to fulfilling the refuge purpose.
Aquatic:
Growing in, living in, or dependent upon water.
