This is the second in a series in which clues are given and the reader is left to guess what is being described.
The mystery is something fairly common in my neck of the woods and in many other places on the planet. Yet you would not see it at the bottom of any ocean. Sometimes a railroad track is all that separates a rich area from a poor neighborhood. In this case, another type of barrier separates those who commonly see the mystery and those who don’t. If the proximity of such a barrier is visited by a cold current, you will experience even less of it on the wrong side of the barrier.
Often you only experience its refreshing smell in the first five minutes. And then it fades like a fragrance does when you distance yourself from a peony. If at its widest point it is no thicker than a human hair, it will not move faster than a spider. Otherwise if the mystery is half a centimeter in size, it will move as fast as the average dog. But if it gets slightly bigger than that, its moving shape will no longer be that of a hamburger bun. Instead it will break up into tiny little spheres, which could grow again.
It can become coated with layers of ice but only in the summer. When conditions are not so humid, if the mystery falls near very dry air, the mystery will take energy away from it, and cool it to the point that the air will rapidly descend . The rapid movement has crashed 5 planes in a recent decade.
What we have in mind cannot be born without dust, pollen or non sea-salt SO42- particles. Even in a world without pollution, there would be an acid in the mystery, albeit one of a different nature, thanks to respiration. Even if the Garden of Eden existed, the addition of carbon dioxide from the breath of Adam and Eve would cause the mystery to pick up ions from rocks and wash them into sea. In other words, it would still be one of two mechanisms that makes the oceans salty. When mass-volcanism and— especially— humans don’t inject excess amounts of carbon dioxide into the atmosphere, the mystery, along with oceans helps keep the amount of carbon dioxide at steady state.
Can you guess what’s being described?