Fine structure of the solar chromosphere: Arch-shaped mottles

We analyze a time series of high resolution observations near the solar lim b, obtained in H alpha and the Mg bl line. We identified arch-shaped dark m ottles, which are thin, faint H alpha structures observable under very good seeing conditions, best seen in H alpha + 0.75 Angstrom. Their mean length is about 15", their mean height about 6'' and indicative lifetimes is of t he order of 5 min. They show negative (away from the observer) line-of-sigh t velocities. A possible interpretation is that material flows from the ape x towards the feet of the arches.