We measure variations in orientation of fourteen dynamic fibrils as a
function of time in a small isolated plage and nearby network using a 10-min
time sequence of H-alpha filtergrams obtained by the Dutch Open Telescope. We
found motions with average angular velocities of the order of 1 deg/min
suggesting systematic turning from one limit position to another, particularly
apparent in the case of fibrils with lifetimes of a few minutes. Shorter
fibrils tend to turn faster than longer ones, which we interpret as due to
vortex flows in the underlying granulation that twist magnetic fields.Comment: In press,"Physics of Chromospheric Plasmas" (Coimbra), ASP 368, 115
(2007