Guardian picture researcher Karin Andreasson says: "Some lovely pictures this month but my cursor keeps pulling me back to Ellen-Mary Pullar's "The sunrise from Tajumulco 4220m". It's just so spectacular and there's something magical and otherwordly about the symmetry. Either a lot of luck or some serious patience, both pretty useful when taking pictures, was needed" Photograph: Ellen-Mary Pullar/guardian.co.uk