Published online by Cambridge University Press: 14 August 2015
Evolution of chromospheric fine structures is discussed from observational points of view. First, various lifetime determinations are reviewed. Then chromospheric oscillation in the interior of supergranule cell is discussed in relation to chromospheric ‘grain’ structure. We show that the grains are collectively associated with the 180-s oscillations as well as that in K line the grain is identified with local disturbance generated at lower level and propagating to upper levels. Finally the details of evolution of individual mottles are presented. We show some cases which indicate the propagation of a disturbance along the mottle axis. Statistics of evolution patterns of mottles implies a significant tendency for a system of double dark mottles encasing a bright mottle.