From her window seat, Maria Popova (Member 38,823) watched as Altocumulus stratiformis radiatus undulatus clouds stretched out across the Atlantic Ocean below. The radiatus part of the classification means the mid-level cloud, Altocumulus, was arranged into parallel bands aligned with the winds that appear to radiate from the horizon due to perspective. The undulatus part means they also had a wavelike, rippled appearance aligned perpendicular to the winds. The stratiformis part means the cloud layer was spread across a large proportion of the sky. In Maria’s words, this is ‘when water becomes beams of light’.