I glanced at the puff piece. Some science and some legacy has been lost in the article.

Cloud seeding for making rain has been a concept since the early 20th century. Maybe the 1930s or 40s?

The modernish concept of "chem trails" a la Alex Jones and David Icke is that chemicals are sprayed from the jet exhaust of jet airplanes in order to perform large scale cloud seeding, or other kinds of environmental modification, and they aren't necessarily just silver iodide.

Chem trails are manifested by jet trails that don't dissipate quickly and which hang in view as long as the winds permit, perhaps up to an hour. Supposedly water vapor is the only component of a pure non chemtrail and dissipates as quickly as it is sprayed out.

What I've read claims of is that some aluminum compound is used for chemtrails and the intention is to embed the chemical in the environment and the soil.

I think silver iodide is also used in film photography to make light sensitive emulsions. Being partly silver, it's gonna cost a ton to seed rain on a large scale.

I wouldn't give the government that much credit. There are currently major epoch scale changes in the solar wind and the interplanetary medium (basically dust and also radiation effects) that are causing visible changes on many of the planets in our system such as temperature swings and atmospheric changes visible from observation. The point is that increased radiation from space can create nucleation points for precipitation. Gamma rays may make it rain and/or increase cloud cover. That can contribute to weird weather.