یک تکنیک برای کم کردن میزان کاهش تابش خورشید به دلیل پوشش ابر و درخت

Radiant energy is produced from direct or diffuse solar short wave and infrared radiation and longwave radiation from heated landscape elements. This paper presents a technique which has been developed for inexpensively and easily estimating the amount of incident radiation reduced by cloud and by three different tree types. The measurement surfaces of cheap temperature sensors with data logging capabilities (iButtons) were coated with either a white gloss or a matt black paint. White gloss paint has an emissivity of ∼0.9 in the longwave spectrum but only ∼0.3 in the short wave, whereas matt black paint has an emissivity of ∼0.95 for both and can be used to detect both short and long wave radiation. The temperature difference between the two gives a measure of the amount of shortwave radiation or visible light. This enabled measurements of cloud shade and local plant shade, and an estimation of the quantity of that shade when compared with full sky exposed reference iButtons. The iButtons can be mounted concurrently at numerous points around a house envelope or in a landscape, at multiple house locations to determine the quantity of shade provided by different native and introduced plant species.