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
Perth Easter weekend weather forecast to be among hottest on record as police caution beachgoers
19:12 EST
Beachgoers have been urged to stick to social distancing rules this Easter long weekend with Perth and parts of the South West set to experience potentially record-breaking heat.
Vanuatu faces 12-month recovery as Cyclone Harold heads for Fiji
15:09 EST
Disaster officials in the small Pacific nation of Vanuatu are working around the clock to assess the damage that a category five cyclone has caused to remote islands, as Cyclone Harold heads for Fiji.
More rain on the way as parts of NSW recover from drought
10:22 EST
More than 15 percent of NSW has come out of drought since the end of last year, with more useful rain on the way in the coming days.
