comments Shift happens. Thought-provoking, powerpoint-ish, reference-free, Friday Fun. posted by HyperBlue at 11:43 AM PST - 48 comments Rare and strange cloud formations. Mammatus , lenticular , noctilucent , nacreous , hole in the sky . Basic cloud guide . posted by nickyskye at 10:09 AM PST - 45 comments Last