Environmental Engineering Reference
In-Depth Information
Amphidromic point
An ocean hub of zero tidal range, around which co-tidal lines
radiate towards adjacent coasts, caused by the impact of Earth's rotation on the tidal
bulge.
Amygdaloidal
The texture of an igneous rock created by the crystallization of secondary
minerals in former gas vesicles or voids.
Anabatic
Said of the inflowing and ascending portion of a local thermal circulation cell,
driven by the warming phase of diurnal heating in a mountainous region.
Anabranching
Said of the individual river channels which form a braided channel reach
where intervening bars are large and stable.
Anaerobism, anaerobic
The absence of free oxygen, or organisms active in the absence
of free oxygen.
Anatexis
The melting of adjacent (country) rock by an igneous intrusion which swells
the size of the developing
pluton
.
Andesite line
An imaginary line dividing the Pacific Ocean and rim into two volcanic
provinces based on their magma petrology and volcanic morphology; intraplate,
basaltic shield volcanoes are distinguished from subduction zone, andesitic
stratovolcanoes.
Anion
An atom which has gained one or more negatively charged electrons and is thus
itself negatively charged.
Annual
A plant that completes its life cycle in one growing season.
Antarctic circumpolar current
The east-flowing, clockwise cold surface current which
encircles the Antarctic continent in the absence of land barriers and feeds cold water
into the anticlockwise
gyres
of adjacent oceans.
Antarctic convergence
The boundary between the north-flowing cold, dense Antarctic
water mass and less dense south-flowing water masses in the adjacent oceans.
Anthropogenic
Said of a process or material originating from human activity.
AOGCM (Atmosphere-Ocean General Circulation Model)
a global climate forecast
model which integrates atmospheric and ocean components.
Aphelion
The point on the orbit of Earth when it is farthest from the sun.
Aquiclude
A rock mass which absorbs underground water but impedes its onward
transfer.
Aquifer
Rocks and sediments capable of storing ground water.
Aquifuge
An impermeable rock mass which arrests underground water transfer.
Aquitard
A rock mass which retards but does not arrest underground water transfer.
Arch
A rock mass spanning a gap weathered or eroded through its core.
Arctic-alpine
Said of the flora or geomorphology of high-altitude and high-latitude
regions, showing common adaptation to, or reliance on, cold climates and
cryospheric
processes; they vary according to differences in daylight regime and general slope
conditions between the two zones. See also
cryonival
and
cryophyte
.
Arctic tundra
The distinctive treeless plant community or broader
geoecological
environment of the Arctic basin polewards of the
timberline
.
Area effect
That part of island biogeography theory which relates the number of plant
colonizers to the size of the island being colonized.
Arête
A narrow, precipitous and frost-shattered mountain ridge forming the remnant
divide between two glacial
cirques
.
