Abstract:
It is shown that pre-flare activity in H-alpha filaments is unrelated to changes in magnetic shear. Changes in the shear angle are found to be related to either redeployment of the sources of magnetic flux relative to the main sunspots or to the emergence of new flux. Without involving any measure of the transverse magnetic field, it is difficult to link changes in the shear angle with changes in magnetic shear. It is also determined that non-potential magnetic fields are necessary for the occurrence of flares.
