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Geophysics, Astronomy, and Acoustics
Published in W. M. Haynes, David R. Lide, Thomas J. Bruno, CRC Handbook of Chemistry and Physics, 2016
W. M. Haynes, David R. Lide, Thomas J. Bruno
The solar luminosity (total radiant power emitted by the Sun) is 3.8281026 W, of which about 1361 W m-2 (the solar irradiance or "solar constant") reaches the top of the Earth's atmosphere (Ref. 6). To a zeroth approximation, the sun can be considered a black body with an effective temperature of 5780 K, which implies a peak in the radiation at around 0.520 m (5200 Å). The actual solar spectral emission is more complex, especially at ultraviolet and shorter wavelengths. The graph in Fig. 1, which was taken from Ref. 1, summarizes the solar irradiance at the top of the atmosphere in the range 0.3 m to 10 m. The solar irradiance undergoes both long-term and short-term variations. Figure 2, which is taken from Ref. 4, shows the shortterm variation over the 1976-2010 period. At the time of those measurements the mean value of the solar constant was believed to be about 1366 W/m 2. The more recent measurements in Ref. 6 show that the mean value (which is more difficult to measure than the short-term variations) is closer to 1361 W/m 2. Thus the curve in Fig. 1 should be shifted down by about 5 W/m 2.
Atmospheric Effects
Published in Wayne T. Davis, Joshua S. Fu, Thad Godish, Air Quality, 2021
Wayne T. Davis, Joshua S. Fu, Thad Godish
Changes in the sun’s luminosity associated with sunspot cycles have, from time to time, captured the interest of climatologists in their attempts to explain climatic change. Ice core and ocean temperature analyses show significant correlations between temperature changes and the 11- and 22-year sunspot cycles. These correlations suggest that changes in solar luminosity may, in part, have contributed to the global warming observed in the last century. However, the potential relationship between changes in sunspot activity and climate changes has been subject to considerable controversy.
Light Sources
Published in Toru Yoshizawa, Handbook of Optical Metrology, 2015
The luminosity of Sun, calculated for surface temperature about 6000 K and radius of 7 × 105 km, is about 4 × 1026 W. This quantity is called a solar luminosity and serves as a convenient unit for expressing the luminosity of other stars.
Effects of a subadiabatic layer on convection and dynamos in spherical wedge simulations
Published in Geophysical & Astrophysical Fluid Dynamics, 2019
P. J. Käpylä, M. Viviani, M. J. Käpylä, A. Brandenburg, F. Spada
The value of in the rotating simulations is chosen such that a solar-like differential rotation is obtained. The current setups with a Kramers-based heat conduction still tend to produce anti-solar differential rotation at solar luminosity and rotation rate. Visualisations of the flow fields realised in representative hydrodynamic runs without (HD2) and with rotation (RHD2), and a corresponding MHD run (MHD2) are shown in figure 1. The non-rotating cases qualitatively resemble mixing length ideas in that the horizontal scale of the convective eddies increases as a function of depth. The rotating cases are dominated by banana cells (e.g. Busse 1970; Gilman and Miller 1986) in the equatorial regions and by small-scale convection at high latitudes, and this carries over also to the magnetic cases. The flow structure in the current MHD runs is typically very similar to the corresponding RHD runs. The convective scales show significantly less variation in depth in comparison to non-rotating convection.
Paleosols and weathering leading up to Snowball Earth in central Australia
Published in Australian Journal of Earth Sciences, 2021
These equations can be used to calculate atmospheric soil CO2 and other components of that calculation for the five calcic (Akngerre) paleosols analysed are presented in Table 3 and plotted in Figure 4j. Values of 1320–1750 ppm are 4.7–6.2 times preindustrial atmospheric level of 280 ppm and are very similar to other estimates of Proterozoic CO2 derived from a different mass balance model (Sheldon, 2006). Values this high produced dangerously high temperatures during the past 300 million years (Retallack & Conde, 2020), but were not so severe 785–717 Ma when solar luminosity was only 94% of modern levels (Feulner, 2012)
The co-evolution of life and organics on earth: Expansions of energy harnessing
Published in Critical Reviews in Environmental Science and Technology, 2021
Guo-Xin Sun, Song-Can Chen, Gang Li, Xiao-Ming Li, Long-Jun Ding, Brian J. Reid, Philippe Ciais, Yong-Guan Zhu
The greatest energy source in the surface environment of the Earth is sunlight. Today the average solar energy flux to Earth surface is 340 W/m2 (Rosing et al., 2006). The early Sun was fainter and solar luminosity was probably a quarter to a third less than the present day (ca 250 W/m2 at 4.0 Gyr; Nisbet & Sleep, 2001; Sagan & Chyba, 1997).