Weather terms starting with U

56 terms

U Burst In solar-terrestrial terms, a fast radio burst spectrum of a flare. It has a U-shaped appear- ance in an intensity-vs.-frequency plot
U.S. Geological Survey (Abbrev. USGS)- The Federal Agency chartered in 1879 by congress to classify public lands, and to examine the geologic structure, mineral resources, and…
UCP (Unit Control Position): The WSR-88D radar operator uses this to control the entire radar system.
UGC (Universal Geographic Code) - (e.g. ANZ300 for Western Long Island Sound) are used in many National Weather Service text products to provide geographical…
UKMET A medium-range (3 to 7 day) numerical weather prediction model operated by the U nited K ingdom MET eorological Agency.
ULJ Upper Level Jet
Ultra High Frequency (UHF) Those radio frequencies exceeding 300 MHz
Ultraviolet Index This index provides important information to help you plan your outdoor activities in ways that prevent overexposure to the sun's rays.
ultraviolet radiation (UL-truh-VY-oh-let RAY-dee-AY-shun) Invisible rays that are part of the energy that comes from the sun.
Ultraviolet Radiation (UV) The energy range just beyond the violet end of the visible spectrum. Although ultraviolet radiation constitutes only about 5 percent of the total energy…
Umbra In solar-terrestrial terms, the dark core or cores (umbrae) in a sunspot with penumbra, or a sunspot lacking penumbra.
Undercurrent A current below the upper currents or surface of a fluid body.
Underflow The movement of groundwater through the soil or a subsurface stratum, or under a structure; specifically, the water flowing beneath the bed of a stream…
Undersun An optical effect seen by an observer above a cloud deck when looking toward the sun, as sunlight is reflected upwards off the faces of ice crystals in…
Undertow A relatively small-scale surf-zone current moving away from the beach. Rip currents form as waves disperse along the beach causing water to become trapped…
Unfinished oils All oils requiring further refinery processing, except those requiring only mechanical blending.
Unimodal A distribution having only one localized maximum, i.e., only one peak.
Unit Control Position The WSR-88D radar operator uses this to control the entire radar system. One of the main things that the radar operator will do at the UCP is change…
Unit Hydrograph The direct runoff hydrograph resulting from a unit depth of excess rainfall produced by a storm of uniform intensity and specified duration.
United Nations Framework Convention on Climate Change (UNFCC) The international treaty unveiled at the United Nations Conference on Environment and Development (UNCED) in June 1992.
United Nations Framework Convention on Climate Change (UNFCCC) The Convention on Climate Change sets an overall framework for intergovernmental efforts to tackle the challenge posed by climate change.
Universal Geographic Code (UGC) - UGC's, (e.g. ANZ300 for Western Long Island Sound) are used in many National Weather Service text products to provide geographical information.
Universal Time (UT) By international agreement, the local time at the prime meridian, which passes through Greenwich, England.
Unmanned Aerospace Vehicle (UAV) Program A U.S. Department of Energy program that uses an unmanned aerospace vehicle and occupied aircraft to make key climate measurements that cannot be made my…
UNSBL Unseasonable
Unsettled In meteorological use: A colloquial term used to describe a condition in the atmosphere conducive to precipitation.
Unstable Air Air that is able to rise easily, and has the potential to produce clouds, rain, and thunderstorms.
UNSTBL Unstable
Up-valley Wind A diurnal thermally driven flow directed up a valley's axis, usually occurring during daytime; part of the along-valley wind system.
Updraft A 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…
Upper air observation Upper air observation An observation made in the free atmosphere either directly or indirectly.
Upper atmosphere Upper atmosphere The general term applied to the atmosphere above the mesopause.
Upper Level In weather observing, the term applies to the portion of the atmosphere that is above the lower troposphere, generally 850 hPa and above.
Upper Level Disturbance A disturbance in the upper atmospheric flow pattern which is usually associated with clouds and precipitation.
Upper Level System A general term for any large-scale or mesoscale disturbance capable of producing upward motion (lift) in the middle or upper parts of the atmosphere.
Upper-air Weather Chart Weather maps that are produced for the portion of the atmosphere above the lower troposphere, generally at and above 850 mb.
UPR Utility, Plant, and Reissue -- see patent for more
Upslope Flow Same as Orographic Lifting; air that flows toward higher terrain, and hence is forced to rise.
Upslope Fog A fog that forms when moist, stable air is carried up a mountain slope.
UPSLP Upslope
upstream The region extending in a 5' direction from a gene.
Upstream Slope The part of the dam which is in contact with the reservoir water. On earthen dams, this slope must be protected from the erosive action of waves by rock…
UPSTRM Upstream
Upwelling In ocean dynamics, the upward motion of sub-surface water toward the surface of the ocean. This is often a source of cold, nutrient-rich water.
upwelling longwave irradiance The rate at which radiant energy, at a wavelength longer than approximately 4 µm, is being emitted upwards into a radiation field and transferred across…
upwelling shortwave radiance The rate at which radiant energy, at a wavelength between 0.4 and 4 µm, is being emitted upwards into a radiation field and transferred across a surface…
Urban and Small Stream Flood Advisory This advisory alerts the public to flooding which is generally only an inconvenience (not life-threatening) to those living in the affected area.
Urban and Small Stream Flooding Flooding of small streams, streets, and low-lying areas, such as railroad underpasses and urban storm drains.
Urban Flash Flood Guidance A specific type of flash flood guidance which estimates the average amount of rain needed over an urban area during a specified period of time to initiate…
Urban Flooding Flooding of streets, underpasses, low lying areas, or storm drains. This type of flooding is mainly an inconvenience and is generally not life threatening.
Urban Heat Island The increased air temperatures in urban areas in contrast to cooler surrounding rural areas.
UTC By international agreement, the local time at the prime meridian, which passes through Greenwich, England.
UV Index Ultraviolet Index- This index provides important information to help you plan your outdoor activities in ways that prevent overexposure to the sun's rays.
UVM Upward Vertical Motion (also known as Upward Vertical Velocity)
UVV Upward Vertical Velocity (rising air)
UWNDS Upper Winds