From: "John Beamish" 

As soon as I read "540" I had an "oh, yeah!" moment. 
Thank you for stimulating those buried neurons!  I don't recall the phrase
"ledge" coming up in the class but it's the perfect word here.

On Sun, 18 Feb 2007 21:37:59 -0500, Monte Davis
 wrote:

>
> Water: takes 1 calorie/gram (by definition) to warm it by 1 degree C
> (or K); it gives off the same when it cools by 1 degree. But at
> freezing/melting, there's an *80* cal/g "ledge" of latent heat; at
> boiling/condensation, a *540* cal/g "ledge." All the numbers are lower
> for most other substances, but the ledges are still there.
>
> So misting water in a citrus orchard or on a strawberry field can save
> the fruit on a freezing night, releasing heat as it freezes. So live
> steam produces  terrible burns, depositing heat as it condenses. Most
> of all, the high latent heats of water moderate the earth's
> temperature. The big energy demands at 0 C and 100C act as flywheels.
> Or governors, or sheet anchors, or whatever metaphor you like for
> "smoothing out extreme variation."
>
> Monte Davis
> http://montedavis.livejournal.com

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