ATMOSPHERIC ATTENUATION OF LIGHT RADIATION FROM A POINT SOURCE IN AN ARCTIC ENVIRONMENT
Twenty-two nighttime measurements were made of the atmospheric effects on light attenuation from a point source during the spring and fall of 1962 at a site on the Greenland icecap (Camp Century). Graphs are included to show the total and indirect intensity fluctuations over 12-second intervals unde...
| Main Authors: | , |
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| Other Authors: | |
| Format: | Text |
| Language: | English |
| Published: |
1964
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| Online Access: | http://www.dtic.mil/docs/citations/AD0615023 http://oai.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=AD0615023 |
| Summary: | Twenty-two nighttime measurements were made of the atmospheric effects on light attenuation from a point source during the spring and fall of 1962 at a site on the Greenland icecap (Camp Century). Graphs are included to show the total and indirect intensity fluctuations over 12-second intervals under various atmospheric conditions. Some comparison is also made of the ratio of indirect/direct intensity vs optical depth under some Arctic and New Jersey shore atmospheric conditions. A much greater indirect/direct ratio in an Arctic environment of almost unity albedo, as compared to a local New Jersey environment of about 0.2 and 0.5 for the total albedo, is evident from some of the results noted. Three 'duct effects' were experienced when a maximum 3.5- fold and twofold increase of total intensity resulted; i.e., cases of 29 Oct and 13 Nov, respectively, compared to an atmosphere with a zero albedo and unlimited visibility, while the 15 Nov situation indicated a maximum 16-fold increase. However, each of the above-mentioned cases was complicated by the presence of some scattered fog patches. Results also indicate that intensities of light pulses from a point light source can vary by more than 100 percent at distances of 4.5 miles over 20-second time intervals. |
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