Mushroom Cloud

The mushroom cloud consists chiefly of very small particles of radioactive fission products and weapon residues, water droplets, and larger particles of dirt and debris carried up by the afterwinds. The color of the cloud is initially red or reddish brown, due to the presence of nitrous acid and oxides of nitrogen. As the fireball cools and condensation occurs, the color changes to white, mainly due to the water droplets as in an ordinary cloud.