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Unformatted text preview: convection from radiative zone to photosphere Photosphere - the "visible" surface of the sun c 6000K Chromosphere - above the photosphere, the temperatsphere, the temperature drops away from the surface to c 4500K and then rises to 8500K. Because it is initially cooler that the photosphere below it, it is marked by the presence of absorption lines in the solar spectrum - particularly the main transitions in the Hydrogen atom like the Lyman and Balmer lines. Noted particularly for H-alpha at 656.3nm Corona - from a process still not completely understood, the "atmosphere" above the chromosphere is heated to temperatures around 10 6 K - this region is the corona. The chemical composition of the upper solar atmosphere is variable and different from that of the surface layers of the Sun. Magnetic field - the sun's magnetic field is generated by dynamo action, though the details are still not entirely understood....
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- Fall '10