Indeed, I've played with it a bit to demonstrate: http://s3.amazonaws.com/clouds-reverse-engineered/index.html

Gah! Now I understand how it works, it does not look nearly as cool as it did before!

I think it looks even cooler because of its simplicity.

Hah! the funny part is that at first glance, I had almost convinced myself that they had implemented a full fluid dynamics system because I was like, "it's even causing a little localized vortex!" :P

Gah! It does look cooler in a geeky way now. Nice!

Agreed, when you know what to look you can see the components, but at first glance it looks very believable.

Too bad even such a simple visual hack was enough to get the fans spinning on my mac air (circa 2011)

Yeah HTML 5 is such a resource hog! Brign back flash :p

The biggest advantage of flash is that it is easy to disable and you don't loose out on disabling it.

Yes, I'm prepared to miss they days of flash.

It's because they don't understand how to properly use canvas, as was pointed out here: https://news.ycombinator.com/item?id=5957101

Oh yes. My CPU-Meter jumped from 3-7% to 35 - 55% while the page was open and dropped back to the previous-level on closing the tab.

Too bad, as it really is a cool effect, done with relatively simple assets...

Interesting. Neither Chrome nor IE or Firefox on Win 8 go above 3 % CPU utilisation here

Same here. Firefox + Win8 and it stays at 2.5% to 3%.

Safari on 10.8.4 and the CPU usage is only 2-3% higher with that tab open. (iMac/2012)

On a Macbook Air 2012 running Mavericks it sits at 1-2% CPU usage...

What browser?

Ahhh, good question. Safari.