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Ultraviolet (UV) Radiation-
A type of invisible light coming from the sun. Visible light
ranges from red, the longest to violet, the shortest. Ultraviolet
rays are shorter than violet and are divided into three types,
UVa, UVb, and UVc.
Undernourished- Refers to
not getting enough nutritious food. Inadequate nutrition can
stunt mental and physical growth in children and lead to major
health problems in children and adults.
Unsustainable- Refers to
agricultural and other practices that depend upon nonrenewable
(or non-replaceable) resources-such as fossil fuel, topsoil,
or groundwater that eventually will be depleted.
Urban- Refers to a city.
An urban area is built up and has a dense population.
Urban Heat Island Effect-
The result of an abundance of dark, hard surfaces in urban
areas. Large amounts of dark materials on roads, sidewalks,
parking lots, and roofs absorb heat from the sun, creating
warmer areas. Increasingly, it can be found in suburbs too.
Urea- Chief end product
of mammalian protein metabolism, formed in the liver from
amino acids and compounds of ammonia; the chief nitrogenous
compound of urine; an average person, in steady state of consuming
average amounts of dietary protein, excretes about 30 grams
of urea per day. |
Uricosuric- pertaining to,
characterized by, or promoting uricosuria (excretion of uric
acid in the urine).
Urinary- Having to do with
urine or the organs of the body that produce and get rid of
urine.
UVa Radiation- A band of
ultraviolet radiation with wavelengths from 320-400 nanometers.
UVa is not absorbed by ozone, and can cause sunburn and skin
damage. UVa also enhances plant life.
UVb Radiation- A band of
ultraviolet radiation with wavelengths from 280-320 nanometers.
It damages DNA and can cause skin cancer, and has also been
linked to damage to crops and marine organisms. The ozone
layer protects the Earth against most UVb.
UVc Radiation- A band of
ultraviolet radiation with wavelengths shorter than 280 nanometers.
Although UVc is extremely dangerous, it is completely absorbed
by ozone (O3) and does not reach the Earth. |
