Does the movement and evolution of clouds look like an irreversible process?

Question

I.e., if you videotaped clouds moving across the sky with no other reference points like the horizon, birds or planes, could someone tell if the film was being run forwards or backwards? Assume they were not present at the taping.

Answer 1

As a weatherman & avid cloud watcher- I can tell if a tape of them is running forward or back...-or even standing still (as is the case of standing wave clouds that form near mountains).

Answer 2

You could *not* tell, based on Brian Greene's book, "The Fabric of the Cosmos". While Dr. Greene was speaking of a hypothetical film of atoms and molecules colliding & bouncing off each other, I infer in a basically chaotic system such as Cloud movement, the same principle would apply. For a non-chaotic system, like an egg rolling off a table and splattering (which Dr. Greene mentions frequently in said book), yes, one could tell if the film were played backward. ENtropy is what underlies my inference. Entropy is a fancy word for "disorder" or chaos.

Answer 3

The concept of reversibility and ireversibility only applies to closed systems. Clouds in the atmosphere are anything but a closed system. Entropy is the most misunderstood concept in science because the idea that entropy always increases cannot be proven for open systems. Fundamentally we do not understand nature well enough to say why it does what it does. We only know "that it does" and "how it does" !

Answer 4

Yes it looks irreversible because the clouds grow and spread out as time goes on.