These phenomena are interpreted as the result of the reconnection above the loop, which convert magnetic energy into thermal and non-thermal energy. However, no direct evidences of reconnection have been detected so far. In this paper, activities in the outer layer of flaring loops are interpreted based on a different scenario.
Centrifugal force acting upward on hot plasma in the loop far exceeds gravity force.
It can develop into nonlinear phase and the outer surface of the coronal loop is broken, then the plasma in the loop is ejected across the field. This instability will play an important role in solar flares. Observational evidences supporting this scenario will be presented.