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National Weather Service Glossary

This glossary contains information on more than 2000 terms, phrases and abbreviations used by the NWS. Many of these terms and abbreviations are used by NWS forecasters to communicate between each other and have been in use for many years and before many NWS products were directly available to the public. It is the purpose of this glossary to aid the general public in better understanding NWS products.

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Nocturnal Inversion
Used interchangably with Radiational Inversion; a temperature inversion that develops during the night as a result of radiational cooling of the surface. Because the immediate surface (lower Boundary Layer) cools much more rapidly during radiational cooling conditions than the air just above (upper Boundary Layer), a temperature inversion can be created overnight, but typically erodes quickly after sunrise.