VISUAL RESOLUTION AND OPTICAL SCINTILLATION OVER SNOW, ICE AND FROZEN GROUND, PART II.

• Main Authors: Portman,Donald J., Ryznar,Edward, Elder,Floyd C.
• Other Authors: MICHIGAN UNIV ANN ARBOR
• Format: Text
• Language: English
• Published: 1965
• Subjects: Atmospheric Physics; Snow; Ice and Permafrost; Optics; *OPTICS; *MICROMETEOROLOGY; ICE; PERMAFROST; LIGHT; SCINTILLATION; VISION; RESOLUTION; PHOTOMETERS; Ice; permafrost
• Online Access: http://www.dtic.mil/docs/citations/AD0630603; http://oai.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=AD0630603

Data obtained over various surfaces were analyzed to determine relationships between visual resolution and meteorological conditions and scintillation (intensity and frequency) and meteorological and surface conditions. The principal results obtained over snow and frozen ground showed that visual resolution, for turbulent flow in stable stratification, (1) deteriorated systematically as the vertical temperature gradient increased, (2) deteriorated with clear skies as the wind speed increased up to about 5 mph and then improved at higher wind speeds, and (3) was optimum and nearly independent of wind speed during low overcast cloudiness. Over a snow-free ice surface and with air temperatures below freezing, only minor scintillation was observed. The scintillation data obtained over ice are interpreted with regard to wind and temperature above the ice and to the heat conducted upward through the ice. A photographic method to measure resolution is described and some results are presented. Power spectra of scintillation over different surfaces are shown and discussed in relation to various meteorological parameters. These and other relations are discussed and equipment and measurement procedures are described. (Author)