"Some amazing facts about life!" Topic

Part 1 YouTube link
Part 2 YouTube link

neat

Very well done.

I love Thunderf00ts videos. One thing I'd like to add about water's qualities for the existence of life is that H2O is the only molecule that is less dense in it's solid form, than in it's liquid form. Without that, life couldn't have survived.

I remember when one of my science teachers pointed that out way back when in high school. Blew my mind! Imagine rivers, ponds, lakes, and oceans freezing from the bottom up.

I had the same sense of awe when another teacher pointed out that, unlike most other plants, grasses grow from the base, not the tip, something I'd never thought of before: en.wikipedia.org/wiki/Grass

I think the rivers and ponds would still freeze from the top, where the colder air was, wouldn't it? But once the ice formed, it would sink, thereby killing everything below. Not really amenable to life.

True, I was using inaccurate shorthand.

Although I wonder what effect "dense ice" would have on cloud formation, air temperatures, ground temperatures, etc.

Hmmm, now that I think of it, as the air chilled the top layer of the water, that water would sink as it got colder (as it does now). That might keep happening until the entire body of water was close to the freezing point, until all of the water suddenly "crossed the line" and froze into a solid mass.

It's an interesting thought exercise.

Part 3 YouTube link

Hmmm, now that I think of it, as the air chilled the top layer of the water, that water would sink as it got colder (as it does now). That might keep happening until the entire body of water was close to the freezing point, until all of the water suddenly "crossed the line" and froze into a solid mass.

If you heat or cool a volume of water you will initiate the movement of convection currents in circular patterns. This way the increase, or decrease in energy attempts to become uniform throughout the system.

That being said, when you make ice cubes, the water still solidifies closest to the cooler air. Similarly, boiling water bubbles always form at the bottom of the pot, closest to the heat source.

I seem to remember my TA in Physical Chemistry studying high density forms of ice. Don't know the specifics but I believe they created ice dense enough to sink through water. But generally the molecules of water in solid form are farther apart than the molecules of water in liquid form. That makes water unique. I don't know of any other material like that.

Although I wonder what effect "dense ice" would have on cloud formation, air temperatures, ground temperatures, etc.

I really don't know. I'd assume cloud formation and snowfall would be unchanged as ice is always denser that gas. I don't know if "molecule bond distance" in a solid would have much effect on temperatures, would it?

We haven't derailed the topic, have we?

Yep. Sorry, Gunfreak.