34th Solar Physics Division Meeting, June 2003
Session 12 Hale Prize Lecture
Invited, Tuesday, June 17, 2003, 5:00-6:00pm, Auditorium

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[12.01] The Dynamic Sun

R. F. Howard (National Solar Observatory)

The Sun presents us with an array of velocity fields, probably the most obvious of which is granulation. A larger convective pattern, supergranulation, is also clearly seen in the chromosphere. There is indirect evidence for still larger organized motions within the convective zone. This evidence comes from the effects of these motions on the orientation and behavior of active regions at the solar surface. As loops of magnetic flux rise through the convective zone to emerge eventually as active regions, they are acted upon by several forces, such as the Coriolis force, and this results in the orientations and motions of the regions observed at the solar surface. The analysis of orientations and motions of regions of various sizes also helps us to understand the forces at work as buoyancy brings magnetic flux to the surface. A picture of the emergence of active-region magnetic flux is now in place that seems to satisfy the observations and our understanding of the dynamo process and the convective zone.

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Bulletin of the American Astronomical Society, 35 #3
© 2003. The American Astronomical Soceity.