Fog in the countryside. Credit: Nickolay Khoroshkov

Fog and contrails over Denmark

16 February 2004 00:00 UTC

Fog in the countryside. Credit: Nickolay Khoroshkov
Fog in the countryside. Credit: Nickolay Khoroshkov

In the early morning hours of 16 February 2004 most of Denmark was shrouded in fog.

Last Updated

24 May 2022

Published on

15 February 2004

Only the island of Bornholm (east-southeast of Copenhagen), still had a clear sky, but the fog was already heading towards it.

Since the Meteosat-8 satellite had only been operational for about 14 days, this was the first opportunity for the Danish Meteorological Institute (DMI) to exploit imagery with a higher frequency and quality when compared to earlier Meteosat image data. Making use of this new imagery, the forecasters were able to predict a very precise arrival time for the fog at the island.

At 07:33 local time, the chief meteorologist forecast the fog to arrive to Bornholm/Ronne Airport (EKRN) around lunchtime and then cover the island within an hour and a half. The time of arrival of the fog was very well predicted as by 13.07 the reported visibility at Ronne Airport fell to 300m, and in less than one hour the whole island was covered in fog.

Not visible to those people experiencing the fog, but extremely visible in Meteosat-8 HRV images, was a sky full of contrails from aircraft at high levels. In the HRV images it is often only the shadow of the contrails on the clouds below that indicates its presence. However, in the IR10.8–IR12.0 difference image (shown below right) they are clearly identifiable day and night. The reason for this is that the high, thin ice clouds have a higher emissivity in the IR10.8 channel than in the IR12.0 channel, and it is this difference that helps identification.

Met-8, 16 February 2004, 12:00 UTC
Figure 1: Meteosat-8 Channel 12 (HRV), 16 February 2004, 12:00 UTC. Animation (08:00–13:45 UTC)
Met-8, 16 February 2004, 12:00 UTC
Figure 2: Meteosat-8 Difference Image IR10.8–IR12.0, 16 February 2004, 12:00 UTC.
Animation (08:00–13:45 UTC)
Met-8, 16 February 2004, 12:00 UTC&
Figure 3: Meteosat-8 RGB Composite HRV, IR10.8–IR12.0, 16 February 2004, 12:00 UTC
Animation 09:00–13:00 UTC
Met-8, 16 February, 12:00 UTC
Figure 4: Meteosat-8 RGB Composite HRV, IR10.8, 16 February, 12:00 UTC
Met-8, 16 February, 12:00 UTC
Figure 5: Meteosat-8 RGB Composite NIR1.6, VIS0.8, VIS0.6, 16 February, 12:00 UTC
Met-8, 16 February, 12:00 UTC
Figure 6: Meteosat-8 RGB Composite VIS0.8, NIR1.6, IR3.9r, 16 February, 12:00 UTC