A Theory of Chromospheric Flares

Abstract

IT has been established from observation that chromospheric flares are closely associated with sunspots, and that the probability of a flare occurring near a spot ncreases with the size of the latter. The probability is higher when the group is increasing its size than when it is stationary, and it is also higher for magnetically complex βγ and γ-groups than for the simpler α- and β-type groups¹. The flares themselves are short-lived phenomena, of mean life about thirty minutes, and are quite localized. It is generally accepted that they show no velocity either in height or across the surface of the sun.