Weather Glossary - U
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UKMETA medium-range numerical weather prediction model operated by the United Kingdom METeorological Agency. |
Ultraviolet radiationElectromagnetic radiation with wavelengths shorter than visible light, but longer than x-rays. Exposure to too much UV radiation can cause skin cancer. |
UnsettledChangeable or variable weather. |
Unstable airAir in which static instability exists. This condition is determined by the vertical gradients of air temperature and humidity. |
UpdraftA small-scale current of rising air. If the air is sufficiently moist, then the moisture condenses to become a cumulus cloud or an individual tower of a towering cumulus or Cb. |
Updraft baseAlternate term for a rain free base. |
Upper levelThe portion of the atmosphere above the lower troposphere. It is generally applied to levels above 850 hPa. |
Upper level systemA general term for any large-scale or mesoscale disturbance capable of producing upward motion (lift) in the middle or upper parts of the atmosphere. This term is sometimes used interchangeably with impulse or shortwave. |
Upslope flowAir that flows toward higher terrain, and hence is forced to rise. The added lift often results in widespread low cloudiness and stratiform precipitation if the air is stable, or an increased chance of thunderstorm development if the air is unstable. |
Upslope fogFog that forms when warm moist air is forced up a slope by wind. |
UpstreamToward the source of the flow, or located in the area from which the flow is coming. |
UpwellingThe rise of colder, deep ocean waters along a coast due to the movement of surface water away from the coast. |
UTCAbbreviation for Universal Time Coordinate. See also Zulu, GMT. |
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Weather News
Wet weather looms for southern and eastern Australia
12:06 EST
Widespread showers and some thunderstorms and snow will affect a broad area of southern and eastern Australia at the end of this week.
Victorian ski resorts restrict Melbourne holidaymakers amid coronavirus outbreak
18:42 EST
Victoria's alpine ski resorts have officially barred visitors from Melbourne coronavirus hotspots, as cases in the state's capital soar.
