Here is a short description of Barium :Barium sulfate is used for its heaviness, insolubility, and X-ray OPACITY as an X-ray RADIOCONTRAST agent for imaging the human gastrointestinal tract. Meaning : Barium is used as a radio-contrast because it STOPS X-rays from passing through and thus leaving white fields on the X-ray Photograph.
So.... If you spray the sky whith Barium along with other Radiation-Blocking metals you are actually creating a RADIATION SHEALD.
BARIUM