Disclaimer: I'm not experienced in many phyiscal nor electrical terms and I have no idea where to ask this question elsewhere. I'd be open for a move request if needed.
Today when using public transport in switzerland I noticed something odd. All trians emitted a lot of sparks where they met the electrical supply line. Seen in different train stations on different trains. (Image not from today, just as example)
I never noticed even in rain. The only difference from other days was the temperature.
Time / Date: 7:15 - 7:40, January 16th
Sky: Still dark, not cloudy
Last snow / rain: The day before yesterday
Can these conditions cause an entire train network to emit sparks? If so why? Is there another possible explinations?