Noctilucent clouds exist in Summer high up in the mesosphere, at an altitude of 76 to 85 km. They occur when temperature in the mesophere reaches its annual minimum below -120°C. NLCs usually are found in the polar regions, but, also in mid latitudes. When the sun is only slightly below the horizon in summer in mid latitudes, the NLCs are still illuminated by sunlight while it is already dark below. Then they become visible as whispy silvery clouds against the dark night sky. In Hannover, where I took the images, they can usually be seen between early June and late July. Best is the time when the sun is between 8° and 12° below the horizon.
2008-07-13
A very bright NLC display in the evening. I noticed it too late so that NLCs were only visibly close to the horizon.
Location: Hannover-Badenstedt
Camera: Canon 40D
Lens settings: 159 mm @ f/4
Exposure: 22:12-22:25 UTC, 6 sec, ISO640
Time lapse movie
Location: Hannover-Badenstedt
Camera: Canon 40D
Lens settings: 159 mm @ f/4
Exposure: 22:12 UTC, 6 sec, ISO640
2008-07-07
A brief and not very bright NLC display in the morning.
Location: Hannover-Badenstedt
Camera: Canon 10D
Lens settings: 70 mm @ f/4
Exposure: 00:59 UTC, 15 sec, ISO400
2008-07-02
A spectacular morning display of NLC. Already faintly visible in the north the evening before, the NLC developed to become very bright in the morning covering a large portion of the norther half of the sky. I reactivated my 10D to be able to capture image series of different interesting parts of the NLC - but, there were so many! I then assembled the image series into AVIs (see below) which show the beautiful development of waves, Kelvin-Helmholtz-Instabilities and their breaking.
Location: Hannover-Badenstedt
Camera: Canon 40D
Lens settings: 38 mm @ f/4.5
Exposure: 22:34-01:33 UTC, 2-25 sec, ISO640
Time lapse movie
Location: Hannover-Badenstedt
Camera: Canon 40D
Lens settings: 38 mm @ f/4.5
Exposure: 00:57 UTC, 15 sec, ISO640
Location: Hannover-Badenstedt
Camera: Canon 10D
Lens settings: 70 mm @ f/4
Exposure: 01:16-01:26 UTC, 8 sec, ISO400
Time lapse movie
Location: Hannover-Badenstedt
Camera: Canon 40D
Lens settings: 38 mm @ f/4.5
Exposure: 01:19 UTC, 5 sec, ISO640
Location: Hannover-Badenstedt
Camera: Canon 10D
Lens settings: 70 mm @ f/4
Exposure: 01:23 UTC, 8 sec, ISO400
Location: Hannover-Badenstedt
Camera: Canon 10D
Lens settings: 70 mm @ f/4
Exposure: 01:27-01:49 UTC, 2-3 sec, ISO400
Time lapse movie
Location: Hannover-Badenstedt
Camera: Canon 10D
Lens settings: 70 mm @ f/4
Exposure: 01:31 UTC, 3 sec, ISO400
Location: Hannover-Badenstedt
Camera: Canon 10D
Lens settings: 70 mm @ f/4
Exposure: 01:35 UTC, 2 sec, ISO400
Location: Hannover-Badenstedt
Camera: Canon 40D
Lens settings: 28 mm @ f/4.5
Exposure: 01:39 UTC, 2 sec, ISO640
Three image panorama
Location: Hannover-Badenstedt
Camera: Canon 40D
Lens settings: 23 mm @ f/4.5
Exposure: 01:42 UTC, 2.5 sec, ISO640
Location: Hannover-Badenstedt
Camera: Canon 40D
Lens settings: 23 mm @ f/4.5
Exposure: 01:42-02:02 UTC, 0.7-2.5 sec, ISO640
Time lapse movie
Location: Hannover-Badenstedt
Camera: Canon 10D
Lens settings: 70 mm @ f/4
Exposure: 01:50-02:08 UTC, 0.5-2 sec, ISO400
Time lapse movie
Location: Hannover-Badenstedt
Camera: Canon 10D
Lens settings: 70 mm @ f/4
Exposure: 01:54 UTC, 2 sec, ISO400