http://www.jennifermarohasy.com/blog/archives/002153.html

“The pursuit of knowledge through scientific enquiry has a rather romantic, even glamorous, image. One imagines all those famous “Eureka!” moments. Well, one has to imagine them because mostly they never happened! However, for those prepared to spend a few minutes looking at the decidedly unglamourous face of practical scientific enquiry, you will do no better than visiting here. The indefatigable Anthony Watts has done us all a service by mounting a national campaign to photograph the climate temperature sites in the USA from which much of the data is used to support ‘Gormless’ Gore and his ilk. That is a story in itself but Watts has taken it one stage further.

All official US temperature recording equipment, at their various sites, is housed in specially designed timber boxes called Stevenson screens and have been so since 1892. Originally the specification for these ‘boxes’ was that they should be painted in whitewash. However, ‘Watts the Diligent’ decided to investigate and found that “… the National Weather Service changed the specification in 1979 to be semi-gloss latex paint.” Why does this matter? Because, as Watts points out, “cured whitewash is composed of Calcium Carbonate, while latex paint uses Titanium Dioxide as a pigment. While they both appear “white” in visible light, they have vastly different properties in infrared.” A very quick and not to be relied on test indicated a difference in temperature between the differently-finished timbers of 2 – 4 degrees at various times.

That was enough for ‘Watts the Seeker of Truth’ to fork out $3,000 of his own money to buy three Stevenson screens to test his hypothesis. One is left unpainted to act as a control and the others are painted respectively in whitewash and semi-gloss paint. He has gone to considerable trouble to pick a site as clear of interference as is possible, in direct contrast to the existing official sites! We now await results – but the results are not the prime importance here, it is the careful, unglamourous but dedicated pursuit of scientific knowledge that Watts exemplifies that is wholly deserving of our admiration and, given the importance of the field in which he is working, our gratitude.

If you need a hand with weeds I can always use a little exercise.

I also have a little Round Up, if that is acceptable.

As for a shortage of “whitewash”… I can certainly see why.

My gosh, look at how much they need to use in Washington and in Sacramento on a daily basis!

Heck, they’re gunna need thousands of gallons of the stuff to try to cover up http://www.surfacestations.org :- )

I should mention that in my quest to ensure accuracy of measurement, I did in fact install a small a/c unit nearby. But it’s not what you think.

By necessity, the data-logger has to be outside, and it is 75 feet away from the screens. I wanted 100 feet, but I could not get calibrated probes with 100 foot cables, so I had to accept what was available.

The data-logger would be exposed to sun, dust, and diurnally varying temperatures. I was also concerned that over 100 degree temperatures might fry the electronics, since they have a 7805 (Lon I’m sure you know the part)voltage regulator on the circuit board with no heatsink.

To remove that worry and potential accuracy problem, I placed the data-logger in one of those 12 volt DC powered “camping coolers” to ensure a constant temperature, shield from sun, and insurance against 110 degree afternoons.

I have two methods:

1- Next week I plan to do some sun angle/treeline measurements, so that I can determine a window within which no shade is received. Because the main driver of the experiment is solar insolation, and because the data is timestamped, I can then exclude data outside that window. IE just look at “full sun” and “full dark” data.

2- you may notice that the screens are not anchored to the soil. The reason for that is so that I can swap positions and run the test again. I also plan to run a test where all three screens are over a concrete slab, gravel, asphalt, etc, since we’ve seen that sort of siting issue. Getting data on how the screens perform over different surfaces is equally important.

Bishop: “The unpainted screen appears to have some grass growing around it. Could this distort the result?”

Indeed it would, but its starthistle, not grass, and it’s density is low. I have permission to bring in a weed wacker next week to take them down.

The actual experiment won’t start for a week, since it will take that long for the whitewash to cure, so if anyone sees issues that need addressing, don’t be afraid to post them.

While I admit the site is not perfect, I had to choose between this site or not doing the experiment at all. I did have a perfect site originally, but the owner had concerns about fire danger that I could not assuage, even though I explained the thermistor cables carry only tiny voltages and currents.

Based on your description I’d guess the two edge boxes (control, historical) are most likely to get it, not the latex box. How do you plan to account for this discrepancy in your data analysis?