This polarity orientation of sunspot groups will generally be maintained until the next sunspot minimum, when the polarities will reverse for both hemispheres. If the axis is highly tilted initially, the group will tend to rotate until the axis is more parallel to the equator. P polarity spots in most bipolar groups tend to be a bit larger and better developed than the somewhat more numerous f polarity spots. P spots in developing groups also tend to move westward to the head of the group. Stable sunspots tend to be fairly symmetrical unless there is extensive magnetic shear nearby from emerging magnetic flux or the passing of an area of opposite magnetic polarity.
Magnetic shearing can cause large portions of sunspot penumbras to distort or vanish.
Large spots generally form from the merger of smaller ones. Large spot groups can be over 182,000 km long and usually result from the emergence of several flux tubes, since individual dipoles rarely exceed 50,000 km in length. Mt. Wilson Classification of Sunspot Groups.