Morphological Analysis and Magnetic Energy Variations of Active Region No. 431

A set of high-resolution sunspot photographs of Active Region No.431 was taken from Nov. 2 to 11 in 1980. On the basis of these data the morphological characters of the active region are analysed. Meanwhile, the twisting angle of the penumbral filaments of sunspots and other parameters are measured and used to calculate the magnetic energy of sunspots. It is shown that the flares observed in the active region could be caused by the releases of the free magnetic energy of sunspots through the comparison of the solar flares with the magnetic energy of sunspots.