(Received: February 19, 2009; Accepted for publication: September 8, 2009)
A method of computer image measurement using digital camera was developed and applied to observe Suspended Particulate Matter: SPM in open-air close to human life. Photos taken by digital camera is very useful to apply many measurements because of their high photographic sensitivity. In this paper we tried to get a character of photos of fine skies. Using digital cameras, we took photos at Miyazaki in the south of the Kyushu island, Mito, Tsuchiura, Tsukuba, and Sangenjaya in the east of the Kanto plain, Utsukushigahara heights where is located in the middle of Nagano, Japan, and Sydney, Australia. Photos were also taken from an airplane flying over the Great Barrier Reef, Australia, to observe air condition in tropopause.
Ratio of Blue and Red (B/R) in digital photos is useful to a marker of purity of air in day time. B/R of fine sky is larger than 2.0. And ratios of green and red (G/R), and blue and green (B/R) of fine sky are larger than 1.5.
A large amount of SPM was observed in tropopause by photos taken from an airplane flying near the equator.
Keywords: Digital photo analysis, Fine sky, Suspended particulate matter: SPM
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