This volume, together with its two companion volumes, originated in a
study commis- sioned by the United States National Academy of Sciences
on behalf of the National Aeronautics and Space Administration. A
committee composed of Tom Holzer, Dimitri Mihalas, Roger Ulrich and
myself was asked to prepare a comprehensive review of current knowledge
concerning the physics of the sun. We were fortunate in being able to
persuade many distinguished scientists to gather their forces for the
preparation of 21 separate chapters covering not only. solar physics but
also relevant areas of astrophysics and solar-terrestrial relations. In
proved necessary to divide the chapters into three separate volumes that
cover three different aspects of solar physics. Volumes I and III are
concerned with "The Solar Interior" and with "Astrophysics and
Solar-Terrestrial Relations." This volume, devoted to "The Solar
Atmosphere," covers not only the chromosphere and corona but also the
principal phenomena usually referred to as "solar activity." The
emphasis is on identifying and analyzing the relevant physical
processes, but each chapter also contains a great deal of descriptive
material.