Cup-type anemometers are not very accurate at low wind speeds though, being unable to measure wind below 0.5 mph. Therefore the milder winds in the array may have gone unrecorded at times. Nevertheless, the data point conclusively toward a reduction of surface air movement caused by the collector arrays, at least for moderate to low wind velocities. Air Temperatures Air temperatures were monitored by constructing stands which contained maximum-minimum type thermometers at 10, 30 and 100 cm above the soil surface. These stands were placed in representative microclimates within the array (Fig. A-l), as well as in the control area. In general, these prelimiminary data on air temperature (Table A-2) indicate an unexpected increase in air temperature within the array. This could be due to the blocking by collectors of long-wave radiation loss, which may be more significant in winter than in other months. Reduced air movement may also cause a heat buildup. The variation in temperatures between heights for each site does not agree with theoretical temperature profile curves, and so are difficult to explain with these limited data. More intensive testing is needed in order to determine if indeed these solar arrays have the potential to create "heat islands", as these preliminary data indicate. Soil Temperatures An extensive network of Colman soil moisture blocks (which also measure temperatures) were placed in the soil in the collector array (Fig. A-l), and three blocks were placed in a similar soil type in the adjacent open desert site. The blocks in the array (Fig. A-l) were subdivided into three types according to the geometry of the array: immediately beneath collectors, shaded gaps, and sunny gaps. This enables an analysis of specific microclimates within the array. Although some areas of the gaps are alternately shaded, blocks 5-7 are almost always shaded, and blocks 8 and 9 were usually in direct sunlight. The temperature sensing element in a Colman block is a thermistor. Temperatures were taken at approximately 1500 hours. Figure A-2 presents soil temperature data averaged for all sites in the array and at the control area for 5 and 30 cm depths. It can be seen that the control area is consistently warmer, particularly at the 5 cm depth, and
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