Thermal Response of a Dry Surface to Shading Cycles of Short Period
1963
Federer, C. A. | Tanner, C. B.
An experiment is presented on the thermal response of a nonevaporating surface (concrete) to square-wave pulses of solar radiation with half-periods ranging from 2 to 20 minutes. Heat flux into the concrete accounted for most of the net radiation but the data was inconsistent due to inadequate temperature sampling. The amplitude ratio of sensible heat to net radiation was 0.01 to 0.10, increasing with period, surface roughness, and wind velocity in agreement with Lettau's theory for sinusoidal net radiation. The amplitude ratio of surface temperature to net radiation (ΔT₀/U₀) increased from 1 to 6°C.ly.⁻¹ min. with increased period. The predicted decrease of ΔT₀/U₀ with increased roughness was approximately that of the experimental results; however, the observed decrease of the ratio with increased wind speed was greater than that predicted by theory.
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