U
Electromagnetic radiation with wavelengths shorter than visible light, but longer than x-rays. Exposure to too much UV radiation from the sun can cause skin cancer.
Time as defined by the rotation of the Earth and determined from diurnal motions reflecting this rotation.
It is expressed in respect of 0° meridian, and used as a standard for comparison of global phenomena. Also known as Greenwich Mean Time (GMT) and Zulu time (military term). See Coordinated Universal Time (UTC).
If an air mass is unstable it contains 'parcels' of air that are warmer or more humid than the surrounding air. This causes them to rise, forming cloud. Unstable air can help thunderstorms develop.
The total amount of terrestrial electromagnetic energy emitted from the Earth's surface that irradiates a specified unit horizontal surface from underneath.
Longwave irradiance emitted by the Earth's surface that irradiates a specified unit horizontal surface from underneath.
In the context of tides, upwelling (upwards movement of water) can occur as a result of periodic flow over uneven topography, especially submarine canyons on the continental shelf.
Upwelling is more often associated with alongshore winds combined with the Coriolis effect, or spatially divergent wind fields over the open ocean. Tidal upwelling can also lead to significant flux of nutrients into the photic zone.
Information about the treatment and reuse of urban wastewater.
Information about water in the urban stormwater drainage system.
Information about wastewater that is disposed of through a sewerage system.
Information about water supplied by urban water utilities.