MEASURING VISIBILITY IN BLOWING SNOW

An electronic system that monitors visibility in blowing snow has been developed by the USDA Forest Service, in cooperation with the Wyoming Highway Department. The sensor for blowing snow is a photoelectric particle counter that produces a voltage pulse for each snow particle which passes through a 3 by 25 mm area normal to the wind. The sensor's pulse train is electronically processed to give voltages proportional to five-second averages of particle frequency and diameter. These voltages are combined with the signal from an anemometer in an analog computer which stimulates visual range according to the equation, V = 5U/sq FX where V is the visual range in meters, U is windspeed in meters per second, F is the particle frequency in number per second through a 1 sq cm area, and X is the particle diameter in centimeters. Field calibration was accomplished by comparison with closed circuit television recording of visual range targets during drifting. The correspondence between theory and observed visual range was very satisfactory, and two such systems are now in use for traffic control in Wyoming, having proved reliable and useful during three winters. /Author/

Media Info

  • Media Type: Print
  • Features: Figures; References; Tables;
  • Pagination: pp 200-207
  • Monograph Title: SNOW REMOVAL AND ICE CONTROL RESEARCH
  • Serial:

Subject/Index Terms

Filing Info

  • Accession Number: 00193879
  • Record Type: Publication
  • Files: TRIS, TRB, ATRI, STATEDOT
  • Created Date: Jun 13 1979 12:00AM