The Dynamical Nature of the Chromosphere

The power spectra for line intensities of lower chro-mospheric lines N i 1319 A and C ii 1335 A are presented. On a number of occasions, intensity oscillations were seen to occur in N i at 3.7 mHz while C ii over the same spatial location showed oscillations close to 2.7 mHz. In a network region, the C ii line intensity was time-delayed by 1 min., compared to the N i line intensity. For network regions, the 5 min. intensity oscillations observed in N i are often accompanied with a blue-shifted line proole of 2{3 km s ?1. These oscillations can be interpreted in terms of kink and sausage waves propagating upwards along thin magnetic ux tubes. These waves can be generated by random foot-point motions driven by exploding granules at the photospheric level.