There is natural high altitude radiation, such as cosmic rays, etc. which has been going on since the beginning of time and the formation of Earth.
What this article focuses on are the changes in the atmosphere that are created by human nuclear bomb testing, nuclear accidents as well as the radioactive high altitude emissions from both nuclear and fossil fuel plants.
How do certain elements such as barium 137, which are created by burning both nuclear and fossil fuels affect the weather plus change the climate?
What is the health impact of breathing in barium, or ingesting it via water?
Are there any measurements of man made barium being found in drinking water, food or soil?
Barium containing rockets have been shot up into the atmosphere in many places around the world, directly into the upper atmosphere. This is one place that provides evidence and data, showing that barium can and does affect colors in the atmosphere.
Since the 1950s, sounding rockets have been periodically sent up into the atmosphere to study high-level winds and the Earth’s magnetic field. Because these fields are invisible to the eye, NASA uses tracer elements such as barium to make their movement visible. When ground-level observers and cameras are in darkness, before sunrise or after sunset, barium is released into the higher levels of the atmosphere — where the sun is still shining.
via Fukushima Plus Other Nuclear Power Plants/Experiments Injecting High Altitude Radioactive Poisons Such As Uranium 235, Krypton, Decays Into Refractory Radioactive Elements Such Cesium, Yttrium, Strontium, Plutonium, Barium 137; Pink/Purple Cloud Color – Negative Health Effects | A Green Road Journal