Do you mean planes leaving trails of clouds or the government openly claiming that it is spraying chemicals on us using planes?
Discussion
...Yes?
Propaganda article from 2018 about spraying sulfur dioxide into the air to darken the sky
https://www.livescience.com/64183-solar-dimming-air-spray-climate-change-cost.html
The spraying planes already exist, just look in the sky...You'll see them every few days spraying in lines in your area. The clouds disperse and linger for hours, blocking sunlight.