Ua-Um

 

UARS

Abbreviation for Upper Atmosphere Research Satellite, a project to carry out the first systematic, comprehensive study of the stratosphere and furnish new data on the mesosphare and thermosphere. See the UARS Web site.

 

UGAMP

Acronym for the U.K. Universities Global Atmospheric Modelling Program, whose approach is to use a hierarchy of models as research tools for controlled experimentation for comparison with observational data and to advance the understanding of atmospheric phenomena. See the UGAMP Web site.

 

UKMO

Abbreviation for United Kingdom Meteorological Office.

 

ultraplankton

Phytoplankton whose lengths range from 0.5 to 10 m. Compare to nanoplankton and microplankton.

 

ultra-violet radiation

Electromagnetic radiation in the approximate wavelength band from 10 to 4000 angstroms (10e-7 to 4x10e-5 cm). This is the wavelength region just below visible radiation. Very little of the total energy contained in solar radiation is found in the ultra-violet portion of the spectrum, and even that small part is strongly absorbed in the high atmosphere. This absorption results in various photo-chemical reactions including that of ozone formation. It also results in a sharp cutoff, at about 2900 angstroms, of the solar spectrum observed at the surface of the Earth. This is felicitous for the life that dwells there given the strong chemical and biological effects produced by ultra-violet radiation. It also explains the present concern about the depletion of ozone by chlorofluorocarbons in the stratosphere.