Clouds affect the climate by positive and negative feedback. To study these effects at local scale, a radiation station was set up, which used two CM21 Kipp ＆ Zonen pyranometers （one inverted）, and two CG1 Kipp ＆ ...Clouds affect the climate by positive and negative feedback. To study these effects at local scale, a radiation station was set up, which used two CM21 Kipp ＆ Zonen pyranometers （one inverted）, and two CG1 Kipp ＆ Zonen pyrgeometers （one inverted） in Logan, Utah, USA. The pyranometers and pyrgeometers were ventilated using four CV2 Kipp ＆ Zonen ventilation systems. Ventilation of pyranometers and pyrgeometers prevent dew, frost and snow accumulation, which otherwise would disturb the measurement. Knowing that available energy （Rn） as Rn = Rsi - Rso ＋ Rli - Rio where Rsi and Rso are downward and upward solar radiation, respectively, and Rli and Rio as atmospheric and terrestrial, respectively, the effects of cloudiness were evaluated on a daily and annual basis. The results indicate that for the partly cloudy days of 4 and 5 September, 2007, cloudiness caused less available energy （Rn） in the amounts of-1.83 MJ·m^-2·d^-1 and -3.83 MJ·m^-2·d^-1 on these days, respectively. As shown, due to cloudiness at the experimental site, the net radiation loss was 2,804 - 4,055 = -1,251 MJ·m^-2·d^-1, which indicates a negative feedback due to cloudiness.展开更多
Concentrating solar power （CSP） technologies could be one of the major contributor to worlds future energy needs and which would be cheap and clean sources of energy. This would improve energy utilization, higher co...Concentrating solar power （CSP） technologies could be one of the major contributor to worlds future energy needs and which would be cheap and clean sources of energy. This would improve energy utilization, higher conversion efficiency with reliable and affordable supply of electricity to the public. The proposed approach is using 18 inch diameter of solar dish concentrator to measure the solar radiation using the aluminium foil as a reflector. In this paper, solar radiation is collected to investigate the solar fraction on incoming solar energy in wet climate.展开更多
Two separate experiments were conducted in bell pepper （Capsicum annum L.） in order to evaluate the effects of temperature and radiation on fruit yield. The results of the temperature experiment were integrated into...Two separate experiments were conducted in bell pepper （Capsicum annum L.） in order to evaluate the effects of temperature and radiation on fruit yield. The results of the temperature experiment were integrated into the radiation experiment to give an overall empirical model for potential pepper fruit yield grown in greenhouse. In the temperature experiment, pepper plants were planted during the summer time of Israel in the Arava region in a commercial, one hectare greenhouse, equipped with a cooling wet-mat system. Eleven plots were assigned along the 80 m down the row from the wet mat. Air seasonal temperatures were affected by the distance from the wet-mat and linearly increased at the rate of 0.036 ℃/m, while relative humidity was not affected. Fruit yield dropped from 19.4 kg/m at a distance of 20 m, to 13.1 kg/m2 at 80 m away from the wet-mat, respectively. Yield regression decreased linearly with increased temperature at -11%/℃. In the radiation experiment, during the summer time of Israel in the Western Negev region, three sweet pepper varieties were grown under six radiation treatments, which accumulated to the following relative global radiation fractions （lint/lout）： 0.72, 0.61, 0.46, 0.38, 0.32 and 0.21 from outside radiation. The three varieties did not differ in their response to radiation. The seasonal temperature normalized yield response to radiation quantity at 21 ℃ （Y21） yielded a linear regression formula with a slope of 7.6 × 10^-3 kg/m^2/MJ. The multiplicative model of temperature and radiation on fruit yield was found to predict well the potential fruit yield for various locations and seasons in Israel.展开更多
文摘Clouds affect the climate by positive and negative feedback. To study these effects at local scale, a radiation station was set up, which used two CM21 Kipp ＆ Zonen pyranometers （one inverted）, and two CG1 Kipp ＆ Zonen pyrgeometers （one inverted） in Logan, Utah, USA. The pyranometers and pyrgeometers were ventilated using four CV2 Kipp ＆ Zonen ventilation systems. Ventilation of pyranometers and pyrgeometers prevent dew, frost and snow accumulation, which otherwise would disturb the measurement. Knowing that available energy （Rn） as Rn = Rsi - Rso ＋ Rli - Rio where Rsi and Rso are downward and upward solar radiation, respectively, and Rli and Rio as atmospheric and terrestrial, respectively, the effects of cloudiness were evaluated on a daily and annual basis. The results indicate that for the partly cloudy days of 4 and 5 September, 2007, cloudiness caused less available energy （Rn） in the amounts of-1.83 MJ·m^-2·d^-1 and -3.83 MJ·m^-2·d^-1 on these days, respectively. As shown, due to cloudiness at the experimental site, the net radiation loss was 2,804 - 4,055 = -1,251 MJ·m^-2·d^-1, which indicates a negative feedback due to cloudiness.
文摘Concentrating solar power （CSP） technologies could be one of the major contributor to worlds future energy needs and which would be cheap and clean sources of energy. This would improve energy utilization, higher conversion efficiency with reliable and affordable supply of electricity to the public. The proposed approach is using 18 inch diameter of solar dish concentrator to measure the solar radiation using the aluminium foil as a reflector. In this paper, solar radiation is collected to investigate the solar fraction on incoming solar energy in wet climate.
文摘Two separate experiments were conducted in bell pepper （Capsicum annum L.） in order to evaluate the effects of temperature and radiation on fruit yield. The results of the temperature experiment were integrated into the radiation experiment to give an overall empirical model for potential pepper fruit yield grown in greenhouse. In the temperature experiment, pepper plants were planted during the summer time of Israel in the Arava region in a commercial, one hectare greenhouse, equipped with a cooling wet-mat system. Eleven plots were assigned along the 80 m down the row from the wet mat. Air seasonal temperatures were affected by the distance from the wet-mat and linearly increased at the rate of 0.036 ℃/m, while relative humidity was not affected. Fruit yield dropped from 19.4 kg/m at a distance of 20 m, to 13.1 kg/m2 at 80 m away from the wet-mat, respectively. Yield regression decreased linearly with increased temperature at -11%/℃. In the radiation experiment, during the summer time of Israel in the Western Negev region, three sweet pepper varieties were grown under six radiation treatments, which accumulated to the following relative global radiation fractions （lint/lout）： 0.72, 0.61, 0.46, 0.38, 0.32 and 0.21 from outside radiation. The three varieties did not differ in their response to radiation. The seasonal temperature normalized yield response to radiation quantity at 21 ℃ （Y21） yielded a linear regression formula with a slope of 7.6 × 10^-3 kg/m^2/MJ. The multiplicative model of temperature and radiation on fruit yield was found to predict well the potential fruit yield for various locations and seasons in Israel.
