Matter is radioactive and decays over time
Henri Becquerel discovered that <span>uranium salts spontaneously emit a penetrating radiation that can be registered on a photographic plate.
hope this helps</span>
Temperature and elevation, if it is cold in Idaho and warm on the eastern end of a mountain side in california (or if warm air is going in that direction) then the cold air, being more dense, will go towards california while the cold air in Idaho will become warm. Same goes for the rest of the world
