[ TERC VHS-1 Sun Photometer ] [ Manual TOC ]
There are many ways to modify the TERC VHS-1. Just be sure that the diameter of the sunlight port and its distance from the LED have the same dimensions as those given in this manual.
It's okay to use a Radio Shack printed circuit board instead of a solderless breadboard. But you will need to solder the parts and wires to the board. It's also possible to use a smaller switch with solder, instead of screw, terminals. Soldering is easy if you know what to do. See "Getting Started in Electronics" (Radio Shack, 1983) for simple soldering instructions and information about electronic parts such as the operational amplifier, LED and resistor used in the TERC VHS-1.
Finally, the solderless breadboard inside the TERC VHS-1 has room for up to two additional amplifiers and LEDs. This means you can expand the instrument to measure other wavelengths of light by using different LEDs. You will need to provide a way to select which amplifier is connected to the voltmeter.
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!