NLCs, Leeds, England.   Imaged by Chris Terran (site) at 01:57UT on 23rd June 2006. The sun was 9° below the ground horizon but still illuminated the 50 mile high clouds. They show their characteristic course and fine wave structures. The long upwards lines are called streaks, the finer grain structures are 'billows'.  Another image was taken at almost the same time but 60 miles further north, the close similarity is testament to the clouds' great height. Image ©Chris Terran, shown with permission.