Glossary |
Select a letter from the index given below,
to be shown those glossary items which begin with the same letter.
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U |
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Ultraviolet radiation |
Electromagnetic radiation with wavelengths shorter than visible light, but longer
than x-rays. Exposure to too much UV radiation can cause skin cancer. |
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Umbra |
That part of the shadow cast by the Earth or the Moon within which the Sun
is completely hidden. |
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Unsettled |
Changeable, variable (Oxford Dictionary). |
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Unstable air |
Air in which static instability exists. This condition is determined by the
vertical gradients of air temperature and humidity. |
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Updraught |
Upward moving current of air of small dimensions. A rapidly moving vertical wind
as found in thunderstorms. |
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Upwelling |
The rise to the surface of cold, deep ocean waters. |
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