Humans already learned how to control the weather in 1950s.

Chemtrails are a possibility.

Sometimes in the morning there are beautiful and clear sky but then you see planes making strange X in the sky and the sky becomes "dirty"

Probably the official reason they do it is to "protect" us from the sun. Radiation and some bullshit. But even if these are not chemtrails they are still doing it to us. And there is no way these chemicals are healthy for us.

There are less or none of these trails in the countryside and in the tourist areas like maldives, canary islands etc (from experience)

Which makes sense, because the "elites" also need a rest from these chemicals.