THE PREDICTION OF AFTERNOON VISIBILITY IN WINTER AT RAF BRIZE NORTON
Abstract
A method was developed for the prediction of afternoon visibility from information available on the midnight soundings of Liverpool, Crawley, Camborne and Hemsby and the value of the 0600Z visibility. The following parameter was important in predicting fog: persistence, 850 MB height gradient, surface temperature, and relative humidity. The method was successful for the period 15 November-28 February. Busts were due largely to visibility dropping rapidly after 0600Z either in pre-frontal fog or moderate snow fall both of which are obstructions to visibility unapproachable by this method. Low incidence of persistent fog during 1-15 Nov and beyond February suggested that including these periods in the study would only complicate the diagrams. The pollution sources of London, Birmingham, Coventry and Nottingham are included indirectly in the 850 MB diagram. It was found that when the surface wind was from these general directions the excess of smoke in the atmosphere would support an occurrence of heavy fog with a much stronger 850 MB height gradient than if the smoke were not so prevalent. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Nov 01, 1960
- Accession Number
- AD0256605
Entities
People
- Richard F. Cummings