In several photos taken with two different cameras, Shows multiple photos with some kind of different size bubbles. In some photos and in others don`t. All taken the same day, with both cameras. They look like some spirits or ghost. What is the explanation. I have taken photos all my life and never seen something like it.

We where Out doors. Not a windy day. We where in a Celebration of a Battle, Cannons and Guns where fired at the distance, Great photos where taken of the cannon and the clouds produced, no bubbles where seen. Later and only in some photos, this Bubbles are seen. And in two different cameras. Please Advice.