Environmental Engineering Reference
In-Depth Information
outermost leaves and twigs inwards, leading to the
death of the tree over several seasons. Dieback has
been linked to the effects of
acid precipitation,
but
there is no conclusive proof that this is the only
factor involved. (See also
Waldsterben
.)
triatomic oxygen
The gas
ozone,
in which each
molecule
consists of three
atoms
of
oxygen
.
tropopause
The upper boundary of the
troposphere
.
It varies in height from about 8 km at the poles to
16 km at the equator.
troposphere
The lowest layer of the
atmosphere,
in
which temperatures decrease with altitude at a rate
of about 6.5°C per kilometre, to reach between-
50°C and -60°C at the tropopause.
TTAPS scenario
The scenario developed to explain
the onset of
nuclear winter
. TTAPS is an acronym
based on the first letters of the names of the
scientists who developed the original hypothesis-
Turco, Toon, Ackerman, Pollack and Sagan.
Tu-144
A
supersonic transport
developed by Tupolev
in the Soviet Union in the 1970s.
damage caused by development projects in
developing nations.
upper westerlies
Westerly winds that blow in the upper
atmosphere close to the
tropopause
in mid to high
latitudes. (See also
jet streams
and
Rossby waves
.)
V
Villach Conference
The first of the major, modern
environmental conferences to deal with the rising
levels of
greenhouse gases
in the
atmosphere
and
their impact on
climate,
held at Villach, Austria in
1985. It established an Advisory Group on
Greenhouse Gases (AGGG) to ensure that the
recommendations of the conference were followed
up.
visible light
Radiation from that part of the spectrum
to which the human eye is sensitive. Visible light
occupies a position between
ultraviolet
and
infrared
radiation
in the spectrum and varies in colour, the
shorter wavelengths being blue and the longer
wavelengths red.
vitamin D
The vitamin essential for the uptake of
calcium by the human body. It is important for the
proper growth and maintenance of bone, and
insufficient vitamin D consumption can lead to
rickets, a disease which causes bones to become
prone to bending and fracturing.
Volcanic Explosivity Index (VEI)
An index for
comparing individual volcanic eruptions. It is based
on volcanological criteria such as the intensity,
dispersive power and destructive potential of the
eruption, as well as the volume of material ejected.
(See also
Dust Veil Index (DVI)
and
Glaciological
Volcanic Index (GVI)
.)
U
ultraviolet radiation
High energy, short-wave,
solar
radiation,
most of which is absorbed by the
ozone
layer in the
stratosphere
. Thinning of the
ozone
layer has increased the proportion of ultraviolet
radiation reaching the earth's surface, giving rise
to fears of an increasing incidence of
skin cancer
and other radiation related problems.
United Nations Conference on Desertification
(UNCOD)
A conference held in Nairobi, Kenya in
1977 which established the modern approach to
the problem of
desertification
.
United Nations Conference on Environment and
Development (UNCED)
An international
conference—the
Earth Summit
—held in Rio de
Janeiro, Brazil in 1992, with the theme of
sustainable development,
based on economically
and environmentally sound principles. (See also
Agenda 21, Global Forum
and
Rio
Declaration
.)
United Nations Conference on the Human
Environment (UNCHE)
Held in Stockholm,
Sweden in 1972, this was the first conference to
draw worldwide attention to the immensity of
environmental problems, thus ushering in the
modern era in environmental studies.
United Nations Environment Program (UNEP)
A
programme designed to combat the environmental
W
Waldsterben
The destruction of the forests. A term
coined in Germany to describe the damage caused
to forests by
acid rain
. (See also
tree dieback
.)
Walker circulation
A strong latitudinal circulation in
the equatorial atmosphere which contrasts with the
normal meridional circulation. It is particularly well
marked in the Pacific Ocean where it is linked with
the
Southern Oscillation
.
water balance
A book-keeping approach to the
moisture budget. It involves the comparison of
moisture input
(precipitation)
and output
(evapotranspiration)
to provide a value for the
net surplus or deficit of water at a specific
location.
