Ultraviolet
Radiation - radiation having
a wavelength shorter than wavelengths of visible light and longer than
those of X rays
Universal
Coordinated Time (UTC) - a global time scale based on
the local time observed on the Prime Meridian; also called Greenwich
Mean Time (GMT) or Zulu (Z) time
Unstable
Air - generally, air which will continue
to rise and accelerate when briefly forced upward
Updraft
- a relatively small-scale current of air
with marked upward motion
Upslope
Flow - air that flows toward higher
terrain and, hence, is forced to rise
Upslope
Precipitation - precipitation
that forms due to moist, stable air gradually forced upward along an elevated
plain (e.g., the Rocky Mountains)
Upstream
- toward the source of the flow, or located in the area from
which the flow is coming
Upwelling
Radiation - the component of radiation
(either reflected solar or emitted terrestrial) directed upward from the
earth's surface; opposite of downwelling
radiation
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