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Solar constant
About: Solar constant is a research topic. Over the lifetime, 967 publications have been published within this topic receiving 29647 citations.
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01 Jan 1977
TL;DR: The Type IV active cavity radiometer (ACR IV) was developed at JPL in 1975-76 as part of the NASA Weather and Climate Program and is capable of defining the absolute radiation scale with an uncertainty near 0.1% and a resolution of 0.02% at nominal solar 'constant' level as discussed by the authors.
Abstract: A Type IV active cavity radiometer (ACR IV) was developed at JPL in 1975-76 as part of the NASA Weather and Climate Program. It is capable of defining the absolute radiation scale with an uncertainty near 0.1% and a resolution of 0.02% at the nominal solar 'constant' level. The ACR IV is the first pyrheliometer capable of measurements at the 0.1% level, which is the threshold of solar 'constant' variability of significance for climatological modeling. A prototype has been tested, and a flight instrument was flown in a 1976 sounding rocket experiment which determined a solar 'constant' value of 1368 W/sq m. A three-detector version of the ACR IV is being developed to monitor the solar 'constant' during 1979-80 as part of NASA's Solar Maximum Mission. Another ACR IV will measure the solar 'constant' as part of the Spacelab I mission in 1980.
1 citations
TL;DR: In this paper, the correlation between microwave solar emissions and the sunspot activity on monthly basis has been found to be high during the maximum phase and in the high cm wavelength band.
Abstract: Observations of solar radio emission at 3 cm wavelength have been made at Japal-Rangapur Observatory for 1980–1981, the solar maximum year using the 3 m radio telescope. The correlation between microwave solar emissions and the sunspot activity on monthly basis has been found to be high during the maximum phase and in the high cm wavelength band. The basic component has been estimated statistically for successive solar rotations using the data obtained at Japal-Rangapur Observatory. Further, this was compared with the data obtained at other cm wavelengths during 1980–1981 and the solar minimum period 1975–1976 of the 21st cycle. The comparison showed pronounced dips in flux levels at different wavelengths during the summer months of the solar maximum year which may be attributed to the presence of coronal holes in the various levels of the solar atmosphere. The computed basic component values showed pronounced variation at high cm wavelengths for the solar maximum period with dissimilar variations at different wavelengths. During the solar minimum period the variations were negligibly small and showed more or less constant level of activity.
1 citations
01 Jan 1973
1 citations
01 Jun 1984
TL;DR: The Active Cavity Radiometer Irradiance Monitor (ACRIM) of the Solar Maximum Mission satellite measures the radiant power emitted by the sun in the direction of the earth and has worked flawlessly since 1980 as discussed by the authors.
Abstract: The Active Cavity Radiometer Irradiance Monitor (ACRIM) of the Solar Maximum Mission satellite measures the radiant power emitted by the sun in the direction of the earth and has worked flawlessly since 1980. The main motivation for ACRIM's use to measure the solar constant is the determination of the extent to which this quantity's variations affect earth weather and climate. Data from the solar minimum of 1986-1987 is eagerly anticipated, with a view to the possible presence of a solar cycle variation in addition to that caused directly by sunspots.
1 citations
01 Jan 2014
TL;DR: In this article, a solar thermal energy driven pump for lifting ground water for irrigation as well as for meeting urban supply system is described, which can save over 93 billion kWh of electrical energy and 3.3 billion litres of diesel (fossil fuel) per year.
Abstract: This paper describes the idea of the development of a solar thermal energy driven pump for lifting of ground water for irrigation as well as for meeting urban supply system. The principles are equally applicable for lifting any liquid, the head being dependent on density of the liquid. This has the potential of saving over 93billion kWh of electrical energy and 3.3 billion litres of diesel (fossil fuel) per year, for India. The invention has been patented. The most attractive feature of the pump is the absence of any moving part, which makes it almost maintenance-free. Syphon action created by water vapour picked-up from the source, lifts the water from the reservoir through the delivery head. This is being demonstrated for the first time. The efficiency of the entire system is also high on account of no moving parts. Solar thermal energy is used to create a pressure higher than the atmospheric pressure, over the surface of liquid to be pumped to height H. The pressure lifts the liquid through a tube dipped below its surface and delivers to head H, determined by additional pressure created through thermal energy and the mass-density of the liquid. Nomenclature Aa = aperture area of PTC in m 2 Sc = solar constant in KW/m 2 Pc = pressure created by solar energy in Pascal, PA = Atmospheric pressure in Pascal Ƥ = Mass density of liquid in kg /m 3 . g = acceleration due to gravity in m/s 2 . h = Enthalpy of steam. H = Discharge height. mw = mass flow rate of water in m 3 /s. ms = mass flow of steam in m 3 /s. V = flow velocity of water in m/s Hs = friction loss in pipe. ɸ = Latitude angle of location where system is installed in degree
1 citations