GNU Image Manipulation Program (GIMP) on GNU/Linux. (1) crop from the original at 4,160 x 3,120 to 4,160 x 1,200; (2) moderate levels adjustment to improve contrast.

This image was taken on an esplanade on the southern side of Old San Juan, with a view (looking southeast) toward the San Juan Bay. A part of the curved city walls are visible to the extreme left. What caught my attention was the Luquillo Mountain Range, which lies about 40 kilometers (25 miles) away and is seen here near the middle of the photograph. This mountainous area forms orographic clouds and rain that project westward into the San Juan metropolitan area, carried away by the trade winds that blow regularly from east to west. Depending on specific wind conditions, these streamers occasionally veer off to the southwest -- like they did on this particular day -- and one can plainly see them on this photograph as a belt of clouds which runs from left to right.