Clouds of the Day - November 30, 2023

The photos below are revealing fall streaks and clouds apparently forming from aircraft engine exhaust. The first photo ice crystals originating out of clear air into falling streamers of ice crystals in very cold air aloft. The crystals are forming at the top of the streamers with the crystals falling away from the origin of formation.

Below those delicate streamers is a denser patch of Cirrus cloud with various filaments of ice crystals being blown by the winds aloft. As you see elsewhere in the cloud photos on other days the differences in wind direction and speed in different layers create awe-inspiring and naturally artistic designs in the clouds.

Below are dramatic Cirrus type clouds trailing dense streamers of ice crystals. Most of the streamers are falling away from dense cloud heads that are cumulus type formations aloft at the cirrus level. In the upper left the streamers are falling immediately out of clear air with no apparent distinguishable head where the streamers begin. The crystals are heavy and large enough to fall immediately upon formation. Where the clouds heads are dense there is enough upward motion to hold the crystals in place until they grow in size enough to fall as streamers. At the bottom of the streamers, where they disappear, the ice crystals are sublimating back into water vapor directly from the ice phase.

I did not witness this cloud formation develop but it looks like it has formed from the water vapor in the engine exhaust of an aircraft condensing directly into ice crystals. These look like Cirrus vertibratus because there are filaments of clouds that are perpendicular to the direction of the parent CONTRAIL that preceded this formation. There are apparently horizontal waves in the clear air that are causing the finger filaments to form horizontally from side to side from the center line of the CONTRAIL. A second example of this process is visible in the left hand photo. It appears to be another CONTRAIL from an aircraft that moved from left to right behind the tree tops.