Organization of review

1.5 Organization of review

In this review, recent observations by new instrumentation are summarized in view of the basic processes involved in the release of magnetic energy resulting in particle acceleration. The material is ordered along the big questions in flare physics:

Section 2: Flare signatures in the photosphere, chromosphere, and corona (Coupling atmospheric layers).
Section 3: Where is the flare energy released? (Flare geometry).
Section 4: Into what forms is the energy released? (Energy budget).
Section 5: Which emissions are direct signatures of energy release? (Signatures).
Section 6: How are particles accelerated? (Acceleration processes).

The literature reviewing flare observations spans more than a century. Substantial summaries of flares observations have been published among others recently by Murdin (2001 ) and Aschwanden (2002 ), in more specialized fields by Bastian et al. (1998 ) on radio emissions, Fletcher and Warren (2003 ) on ultraviolet emissions, Ryan et al. (2000 ) and Schwenn (2006 ) on flare effects and energetic flare particles in interplanetary space. Somov (1992 ), Tajima and Shibata (1997 ), and Priest and Forbes (2000 ) have reviewed theory. Older reviews, such as Sturrock (1980 ) and Švestka (1976 ) are still worth reading. The Astrophysics Data System lists more than 14,500 articles on the keyword “solar flare”. Any review, including this one, can only focus on a small fraction of the accumulated information. Comments and suggestions are welcome.