1. 09:55:30 0 2. 09:56:42 1 3. 09:58:42 3 4. 10:01:02 5½
5. 10:02:38 7 6. 10.04:40 9 7. 10:06:22 11 8. 10:09:08 13½
9. 10:11:40 16 10. 10:14:30 19 11. 10:17:42 22 12. nearby cirrus cloud
Figures
1–11 show the transformation of a
circular persistent contrail into a contrail cirrus cloud over ~20 min
after contrail formation. Parts of the circle are subsaturated at
formation, indicating the small-scale variability in relative humidity.
In these dry areas (at the left hand portion of the circle), newly
formed contrail particles sublimate quickly. The resulting
contrail cirrus remains distinct from natural cirrus that existed nearby
(last figure 12). The puffy nature of the cirrus cloud suggests that it
formed within an area of enhanced small-scale turbulent air motions, in
which also the contrail evolved.
The
sequence has been taken with a Panasonic DMC-LX1
digital camera on June 4, 2007, in Sithonia, Greece, at 40.8N/23.45E.
The contrail cirrus was rapidly advected away from this site. Vertical
shear of the horizontal wind and turbulence spreaded and rotated the
cloud and
distorted its shape. Figure captions give local
times (hrs:min:sec) followed by approximate contrail cirrus age (min).
1. 09:55:30 0
2. 09:56:42 1
3.
09:58:42 3
4. 10:01:02 5½
5. 10:02:38 7
6. 10.04:40 9
7.
10:06:22 11
8. 10:09:08 13½
9. 10:11:40 16
10. 10:14:30 19
11. 10:17:42
22
12. nearby
cirrus cloud
B. Kärcher, DLR
Oberpfaffenhofen, Institute of Atmospheric Physics