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Air pollution
Haze often occurs when dust and smoke particles accumulate in relatively dry air. When weather conditions block the dispersal of smoke and other pollutants they concentrate and form a usually low-hanging shroud that impairs visibility and may become a respiratory health threat. Industrial pollution can result in dense haze, which is known as smog.
Since 1991 haze has been a particularly acute problem in Southeast Asia. In response the ASEAN countries agreed on a Regional Haze Action Plan (1997) and later signed the Agreement on Transboundary Haze Pollution (2002). Under the agreement the ASEAN secretariat hosts a co-ordination and support unit.[2]
Obscuration
Haze causes issues in the area of terrestrial photography, where the penetration of large amounts of dense atmosphere may be necessary to image distant subjects. This results in the visual effect of a loss of contrast in the subject, due to the effect of light scattering through the haze particles. Unlike other atmospheric effects such as cloud and fog, haze is spectrally selective: shorter (blue) wavelengths are scattered more, and longer (red/infrared) wavelengths are scattered less. For this reason many super-telephoto lenses often incorporate yellow filters or coatings to enhance image contrast.
Infrared (IR) imaging may also be used to penetrate haze over long distances, with a combination of IR-pass optical filters (such as the Wratten 89B) and IR-sensitive detector.
Turbidity
With production of plastic films haze has technical significance as the percentage of light that is deflected more than 2.5° from the incoming light direction.[3]
See also
Notes
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