Curious as to where and when you saw this with your Dad?I recall being in the car with my dad when I was a kid and seeing one of these:
Source: https://www.nasa.gov/mission_pages/sounding-rockets/tracers/metals.htmlBarium is used to study the motion of both ions and neutrals in space. A fraction of a barium cloud ionizes quickly when exposed to sunlight and has a purple-red color. Its motions can be used to track the motion of the charged particles in the ionosphere. The remainder of the barium release is neutral, having a different color, and can be used to track the motion of the neutral particles in the upper atmosphere. A small quantity of strontium or lithium is sometimes added to the barium mixture to enhance the neutral barium emissions, making it easier to track the neutral cloud. Since the observer must be in darkness while the barium cloud is in sunlight, the technique is limited to local time observations near sunset or sunrise.
Sounds like what you describe.
What I remember reading about was a single large, iridescent blob that eventually faded away. It was originally reported as a UFO, then a couple days later the rocket/chemical explanation was given.