While I would like to give You news that the Rainbow Colors You are seeing in the Clouds are
Benign - I cannot in all good conscience, do so...
The reason why We're seeing Rainbow Colors in the Clouds nowadays is because of all of the Barium and Aluminum Oxide being dispersed by
Project S.H.I.E.L.D. - Formerly,
Operation Cloverleaf since 1998 approx.
This Rainbow effect is caused by refraction of the Sun's rays through these Chemicals (
A Prism-like effect that is) which now lace most Cloud formations Worldwide...