Irish Weather Online's Fergal Tierney writes:
This is an interesting article, taken from the Satrep Online website:
Black contrails
A nice view was offered to us this morning with the high resolution visible of Meteosat 9. Over Hungary and Romania a persistent shield of fog and stratus is observed. Situated over these we find contrails produced by numerous airplanes. These ice clouds cast a shadow on the underlying cloud shield, hence we see them as black contrails in this HRV (High Resolution Visible) image.
Also nice in this respect is to observe how the Carpathian mountains and mountains in Transylvania are penetrating this cloudshield. A close view even shows that some of the smaller valleys in the Carpathian Mountains are covered by a layer of low clouds and fog and some of the mountain peaks covered by snow.
And while your are at it and concentrating, you can even identify some river valley fog of the Danube in Serbia (bottom center of the image).
