1. Example of Fog over Northern Europe  24 Feb 2004; a winter case, fog over cold snow surface  29 May 2004; fog over sea drifting ashore Pirkko Pylkkö Finnish Meteorological Institute (See alsowww.knmi.nl/satrep Satrep Manual)www.knmi.nl/satrep 1/30.6.2004

2. Winter case; 24 Feb 2004 Fog over snow surface: Fog top warmer than surrounding snow surface => in IR channels fog darker than surface In the winter mostly nighttime or twilight conditions 10.8 and 12µm channels better than 3.9µm for fog above cold snow at night Next pages: First AVHRR 10.8 and 3.8µm images and then same channels from SEVIRI (date 24 Feb 2004 0130UTC) 2/30.6.2004

3. AVHRR 10.8µm Fog

4. AVHRR 3.7µm

5. SEVIRI 10.8 µm Fog

6. SEVIRI 3.9µm Fog

7. 7/30.6.2004 Fog over sea; 29 May 2004 Daytime fog can be seen also in visible channels very well SEVIRI HRV can be of assistance also in the north Animating SEVIRI images makes fog more easy to recognize Following pages: SEVIRI 1.6, 0.8 and 0.6 µm AVHRR channels 0.6, 0.8, 10.8µm

8. SEVIRI 1.6, 0.8, 0.6 µm combination 29 May 2004 1345UTC

9. SEVIRI 1.6, 0.8, 0.6 µm combination 29 May 2004 1400UTC

10. SEVIRI 1.6, 0.8, 0.6 µm combination 29 May 2004 1430UTC

11. SEVIRI 1.6, 0.8, 0.6 µm combination 29 May 2004 1500UTC

12. SEVIRI 1.6, 0.8, 0.6 µm combination 29 May 2004 1515UTC

13. SEVIRI 1.6, 0.8, 0.6 µm combination 29 May 2004 1530UTC

14. SEVIRI 1.6, 0.8, 0.6 µm combination 29 May 2004 1545UTC

15. SEVIRI 1.6, 0.8, 0.6 µm combination 29 May 2004 1600UTC