Hands On Physics


1. The modern era of Sun photometry began with the development of hand-held instruments by Frederick E. Volz, who described his work in "Economical Multispectral Sun Photometer for Measurement of Aerosol Extinction from 0.44 um to 1.6 um and Precipitable Water" (Applied Optics, 13, 8, 1732-1733, 1974).

2. The use of light-emitting diodes as light detectors in an inexpensive Sun photometer was described in a peer-reviewed journal by Forrest M. Mims III in "Sun Photometer with Light-Emitting Diodes as Spectrally Selective Detectors" (Applied Optics, 31, 33, 6965-6967, 1992).

3. The TERC VHS-1 Sun Photometer is based on a design by Forrest M. Mims III published in "Science Fair: Ticket to Your Future" (Radio Shack, 30-31, 1992) and in "Engineer's Mini-Notebook: Environmental Science Projects" (Radio Shack, 37-41, 1995).

4. Many of the basic concepts described here are adapted from "How to Measure the Solar Constant" by Forrest M. Mims III (Science Probe: The Amateur Scientist's Journal, 1, 2, 93-100, 123, 1991).
5. The software that supports this unit and the discussion on Sun angle, air mass and local time are adapted from "How to Measure the Ozone Layer" by Forrest M. Mims III (Science Probe: The Amateur Scientist's Journal, 2, 4, 45-51, 1992). The TERC VHS-1 spreadsheet can be downloaded from: ftp://concord.org/pub/haze/vhs1-download/

Further Reading

Many articles on haze have been published in magazines. See, for example, "Lost Horizons" by Stephen F. Corfidi (Weatherwise, 12-17, June/July 1993); "The Parasol Effect" by David Berreby (Discover, 44-50, July 1993); and "Haze Clouds the Greenhouse" by Richard Monastersky (Science News, 141, 232-233, April 11, 1992).

Hundreds of papers on haze and its measurement have been published in scientific journals. An especially good general paper is "Haze and Sulfur Emission Trends in the Eastern United States" by Rudolf B. Husar and William E. Wilson (Environmental Science Technology, 27, 1, 12-16, 1993).

Astronomer Robert G. Roosen has specialized in interpreting old Sun photometer data collected by the Astrophysical Observatory of the Smithsonian Institution at various sites around the world from the early part of this century until the 1960's. See, for example, Dr. Roosen's classic paper, written with Ronald J. Angione and Clara H. Klemcke, "Worldwide Variations in Atmospheric Transmission: 1. Baseline Results from Smithsonian Observations" (Bulletin of the American Meteorological Society, 54, 4, 307-316, 1973).

An excellent reference on haze in the United States is "Acidic Deposition: State of Science and Technology, Report 24, Visibility: Existing and Historical Conditions--Causes and Effects," John C. Trijonis et al., U. S. Government Printing Office, 1990.

How Sun photometers on the ground are used to verify Sun photometers in satellites is described by G. S. Kent, M. P. McCormick and P. -H. Wang in "Validation of Stratospheric Aerosol and Gas Experiments I and II satellite aerosol optical depth measurements using surface radiometer data (Journal of Geophysical Research, 99, D5, 10,333-10,340, 1994).

You can find more articles on haze by looking under the keyword "haze" in various reference indexes at a library.

For more information on finding the local apparent time for your location, see The USA Today Weather Almanac (Vintage Books, 1995). You can also find information on this subject in basic books about astronomy and sun dials.

At the time of this writing, there is very little information about haze on the Internet. Hopefully, your data will someday appear there!

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