What are Significant Features of the Photosphere?
This answer is courtesty of Ellen Zweibel, University of Colorado.
The photosphere has an average temperature of about 5800 K. Most of its structure is associated either with convection or with magnetic fields. Convection appears in the form of so-called granules, in which the temperature varies by a few hundred degrees from center to edge, and there is an upwelling at the center and downflow at the edge that can be about 1 km per second. The granules form a larger pattern of so-called supergranules, with about 1000 granules per supergranule. At the edges of the supergranules there are thin tubes of intense magnetc field strength. The magnetic field in these tubes is several hundred times larger than the magnetic field of the Earth, but they cover only a small fraction - less than a percent - of the solar surface.
There are good pictures of supergranules, and also magnetograms, on the MDI Web Page.
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Special Thanks to E. Zweibel