Sunspot Group Classification

(Modified Zurich Sunspot Classification). A - A small single unipolar sunspot or very small group of spots without penumbra . B - Bipolar sunspot group with no penumbra. C - An elongated bipolar sunspot group. One sunspot must have penumbra. D - An elongated bipolar sunspot group with penumbra on both ends of the group. E - An elongated bipolar sunspot group with penumbra on both ends. Longitudinal extent of penumbra exceeds 10 deg. but not 15 deg. F - An elongated bipolar sunspot group with penumbra on both ends. Longitudinal extent of penumbra exceeds 15 deg. H - A unipolar sunspot group with penumbra.