In Erdenheim, Pennsylvania, US, Janet Cass (Member 43,965) noticed a strange light flooding in through her windows. She stepped outside and saw this huge, rosy Cumulonimbus mamma cloud. It was like a sky full of pink cream puffs. Mamma, which are also know less officially as mammatus, are pouch-like features that hang from the underside of a cloud layer. Nobody knows for sure how they form, but the most dramatic ones are always found under the spreading canopies of giant storm clouds like Janet’s Cumulonimbus. ‘The colour changed as the Sun set,’ she told us, ‘soon turning into a deep orange against the darkening sky.’