From The Brains Behind Brains on, this is The Moment of Um.

Moment of Um comes to you from APM Studios. I'm Ruby Guthrie.

Oh, hey! What am I up to? Well, I'm just staring at this pot of water, waiting for it to boil.

No, it's not a variation of my normal Tuesday activity watching paint dry. I mean, I'm literally

making spaghetti, and I need this water to boil

ASAP. It's getting there. You can already see the water starting to steam. Man, it's like I'm at the

spa. Mmm, spaghetti steam bath with a side of marinera massage. Ooh, and a faccia face mask? Oh, sorry, I'm having a real

stream of consciousness moment here. Or should I say steam of consciousness? Because my thoughts are

wafting up like all this steam from my pasta pot. Hey, now that I think about it, why does steam travel up?

"'I feel like water almost always travels down, not up.

"'Think about it.

"'Rain falls down.

"'Snow falls down.

"'When I filled this pot with water from the sink, it traveled down from the tap

and into the pot. But now that the water is finally boiling, the steam travels up. Hmm, what's up

with that? Ty and Ellie were wondering about this too. Hi, my name is Ty.

And I'm Ellie.

And we're from Salt Lake City, Utah.

Our question is, if steam is just tiny droplets of water in the air and water moves down when poured out, shouldn't steam travel down too?

So why does steam travel up rather than down?

So steam rises instead of falls because it's lighter than the air surrounding it, whereas water is heavier.

Hi, I'm Nicole Sharp, and I'm an aerospace engineer. One thing to think about here is what happens when liquid water turns into steam. Basically,

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