Serendipity and The Citizen Scientist

Forrest M. Mims III

This and the past issue of The Citizen Scientist were largely assembled in Hawaii, where I recently spent three weeks teaching atmospheric science to a class of university students from eight nations and calibrating instruments during treks to the famous Mauna Loa Observatory at 3,400 meters (11,200 feet) over the Pacific Ocean.

Serendipity played unexpected roles in assembling this issue.

My students this year included several accomplished photographers, including Ji Hyun Chang from Brazil. Ji used his digital Nikon SLR to make sequences of images that he stitched together to form beautiful panoramic views from Hawaii's Mauna Kea. Three of his panoramas appear in this issue's "Gallery."

Then there was the ultraviolet study conducted by two of my students. The same day they began a science project to measure the UV-B wavelengths that promote the synthesis of vitamin-D in the skin of vertebrates, former NASA scientist Bill Grant submitted a feature article on his measurements of the vitamin-D action spectrum for a year in San Francisco. Dr. Grant's article appeared as the lead feature in the 02 June 2006 issue of TCS ("Rates of Vitamin D Production from Solar Ultraviolet B Irradiance in San Francisco During One Year"). Dr. Grant and my students used the same model vitamin D radiometer for their studies, a Vitamin D3 meter from Solartech, Inc.

During his one-year study, Dr. Grant measured peak (solar noon) vitamin D production rates (VDPR) of about 15 International Units/minute in winter and about 67 I.U./min vitamin D production rates during summer.

The student measurements in Hawaii were made by Tsion A. Alemayehu (Ethiopia) and Chelsa Kallis (USA), both at the University of the Nations (Fig. 1). Because of cloud cover and the ever present layer of volcanic emissions known locally as vog, their measurements near sea level fluctuated wildly. At the high-altitude Mauna Loa Observatory, they measured as much as 97 I.U./min vitamin D. Clouds prevented measurements at solar noon on the mountain, so we assumed that the clear sky solar noon value would be higher. I confirmed this several days later on a day when the sky was totally clear at the observatory. The meter indicated 113 I.U./min vitamin D at solar noon.

Studies of vitamin D production rates by natural sunlight have become increasingly important because of a range of new medical studies that report widespread vitamin D deficiency in people living within the temperate latitudes. Various other studies have reported on previously unexpected beneficial effects of vitamin D including reducing the rates of several of the most serious cancers.

There is considerable irony in this, for it is well known that too much sunlight exposure can cause skin cancer. Some of the same wavelengths of UV-B that cause skin cancer promote the synthesis of vitamin D with high efficiency. Scientists like Bill Grant and others are now exploring safe levels of sunlight exposure that will provide the benefits of desirable levels of vitamin D without the risk of skin cancer. Some of Dr. Grant's suggestions are discussed in his article.

The long-term measurements by Bill Grant and the short term project by the two students in Hawaii demonstrate how a professional scientist and students can study the same phenomenon using identical instruments. Citizen scientists can contribute to this research by making their own measurements. How, for example, are vitamin D production rates affected by air pollution, cloud cover and the seasons? Are there any trends at particular locations? How much vitamin D production occurs in shaded spots?

If you take a vitamin D meter on vacation, you can study how vitamin D production rates are affected by latitude. Of special interest would be measurements made in the Southern Hemisphere, for the elliptical orbit of the earth around the sun places the Earth closer to the sun during summer in the Southern Hemisphere than when the Northern Hemisphere is in summer. Assuming the same ozone conditions and a clear sky, this is why UV-B rates at sea level in Australia can be around 7 percent higher at the summer solstice than at the summer solstice at the same latitude in the northern hemisphere.