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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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TL;DR: The ionopause height for values of the solar zenith angle below about 50 deg regardless of the phase in the solar cycle was found to be generally low at times of solar minimum and intermediate solar activity as discussed by the authors.
Abstract: Results are presented of observations from the changes in the electron density structure of the dayside ionosphere of Venus that were brought about by changing solar activity. The ionopause height is generally low for values of the solar zenith angle below about 50 deg regardless of the phase in the solar cycle. At solar maximum, and at times of intermediate solar activity, the ionopause height for solar zenith angles greater than about 50 deg is highly variable, ranging from a minimum of about 200 km to a maximum of more than 1000 km. At times of solar minimum the great majority of all ionopause heights for all solar zenith angles are uniformly low, lying between 200 and 300 km. It is argued that the compressed nature of the Venus atmosphere at solar minimum is produced by permeation of the ionosphere by the solar wind magnetic field, which occurs when the solar wind dynamic pressure exceeds the ionospheric plasma pressure.
50 citations
TL;DR: In this article, the authors demonstrate that a much more modest ISM density of 102−103 cm−3 (a value typical of dense interstellar clouds in spiral arms) would prevent the solar wind from reaching the Earth, and propose that such a change in the Earth's space environment may trigger drastic climatic changes.
Abstract: SEVERAL authors1–3 have discussed whether past immersion of the Solar System in dense interstellar matter (ISM) might have left observable imprints on the Earth. Accretion cannot affect the solar constant significantly unless the surrounding ISM attains densities of 105–107 cm−3 (refs 2 and 3). We demonstrate here, however, that a much more modest ISM density of 102–103 cm−3 (a value typical of dense interstellar clouds in spiral arms) would prevent the solar wind from reaching the Earth, and propose that such a change in the Earth's space environment may trigger drastic climatic changes.
50 citations
TL;DR: In this article, a method of computing the intensities of direct, diffuse, and total solar radiation received on a horizontal surface of the earth is developed by consideration of sky radiation, terrain reflection, and depletion by dry air, water vapor, dust, and clouds in the atmosphere.
Abstract: A method of computing the intensities of direct, diffuse, and total solar radiation received on a horizontal surface of the earth is developed by consideration of sky radiation, terrain reflection, and depletion by dry air, water vapor, dust, and clouds in the atmosphere. The calculation is extended aloft, and a general equation is derived expressing the atmospheric transmission coefficient with cloudless sky at any altitude between 300 and 8000 meters as a linear function of solar zenith distance and logarithm of elevation. The contribution of solar radiation to the heat load on man is then evaluated and expressed as an equivalent increment of temperature.
49 citations
TL;DR: The Michelson Doppler Imager on board the Solar and Heliospheric Observatory satellite has operated for over a sunspot cycle as mentioned in this paper and provides a nearly continuous record of the solar radius in combination with previously developed algorithms.
Abstract: The Michelson Doppler Imager on board the Solar and Heliospheric Observatory satellite has operated for over a sunspot cycle. This instrument is now relatively well understood and provides a nearly continuous record of the solar radius in combination with previously developed algorithms. Because these data are obtained from above Earth's atmosphere, they are uniquely sensitive to possible long-term changes of the Sun's size. We report here on the first homogeneous, highly precise, and complete solar-cycle measurement of the Sun's radius variability. Our results show that any intrinsic changes in the solar radius that are synchronous with the sunspot cycle must be smaller than 23 mas peak to peak. In addition, we find that the average solar radius must not be changing (on average) by more than 1.2 mas yr{sup -1}. If ground- and space-based measurements are both correct, the pervasive difference between the constancy of the solar radius seen from space and the apparent ground-based solar astrometric variability can only be accounted for by long-term changes in the terrestrial atmosphere.
49 citations
TL;DR: This paper represents a comprehensive review of Mir Space Station radiation data available from a variety of sources and indicates that there is a factor of about two in dose rate within a given module, and a similar variation from module to module.
49 citations