Noticed the same thing in the USA as far back as 2008 if not far further back.
It starts with a 100% clear sky, then a plane flies by. The contrail - if you want to call it that paints a line. But then that line doesn't dissipate, instead it gets amplified into a very large cloud with in 10-20 minutes. Another plane goes by this repeats.
Within an hour or two the sky is fully cloudy, but not normal fluffy clouds like you see in cartoons, it's more like a very dispersed haze. When you see normal clouds, that as kids you'd assign/recognize shapes as "That's a bunny, or that's a dog" or whatever, they generally move in one piece, mostly keeping their shape as the wind pushes them. These don't, they spread out rapidly.
After some time the color of the sky changes from the original deep blue, to a lighter shade of blue like you see on the left side of this image, but if you look closely you'll see it's uneven in color and can make out the "clouds" that cause this.
Sometimes you can see waveforms in these kinds of "clouds" that would remind you of sinusoidal interference waves, like you'd see from above in an ocean or sea, - not sure what's causing that effect, but it sure is interesting to speculate.
Anyone with the patience to keep looking up will have noticed this. It doesn't happen all the time, but it does happen often enough.
They did this to increase the chances that it will rain.
I just checked the Norwegian weather forcast. There is an 87% chance of rain tomorrow.
EDIT: In Oslo.
Cool. It's now up to 90% chance of rain in Oslo.
Noticed the same thing in the USA as far back as 2008 if not far further back.
It starts with a 100% clear sky, then a plane flies by. The contrail - if you want to call it that paints a line. But then that line doesn't dissipate, instead it gets amplified into a very large cloud with in 10-20 minutes. Another plane goes by this repeats.
Within an hour or two the sky is fully cloudy, but not normal fluffy clouds like you see in cartoons, it's more like a very dispersed haze. When you see normal clouds, that as kids you'd assign/recognize shapes as "That's a bunny, or that's a dog" or whatever, they generally move in one piece, mostly keeping their shape as the wind pushes them. These don't, they spread out rapidly.
After some time the color of the sky changes from the original deep blue, to a lighter shade of blue like you see on the left side of this image, but if you look closely you'll see it's uneven in color and can make out the "clouds" that cause this.
Sometimes you can see waveforms in these kinds of "clouds" that would remind you of sinusoidal interference waves, like you'd see from above in an ocean or sea, - not sure what's causing that effect, but it sure is interesting to speculate.
Anyone with the patience to keep looking up will have noticed this. It doesn't happen all the time, but it does happen often enough.