Moonrise and Cirrus Clouds
November 21, 2008
The photo above showing the rising, waning gibbous Moon and wavy cirrus clouds was taken from a beach in southern Brazil on May 22, 2008. Though it’s hard to make out, the Moon is rising into the constellation of Scorpius. If you click on the photo you can see an enlarged photo showing more detail. Unknown to me a friend was taking a similar picture at the same moment at a location 60 miles (96 km) to the northwest. His photo contained the same cirrus cloud formation, despite the distance between us.
Cirrus clouds form at heights of about 20,000 to 40,000 feet (about 6,100 to 12,200 m). This is so high that if an observer could stand on a cirrus cloud at 25,000 feet (7,600 m) his or her field of view would cover, from one horizon to the opposite one, some 194 miles (312 km). Note this map showing the exact locations of the two photos. My photo is the lower photo in the link. Here the clouds appear a little bit higher than they do in the upper photo. In my friend's photo an extra cloud appears, parallel to the others but out of the field in my photo. Note also the glitter path on the sea surface in the foreground.