Wednesday, November 22, 2006

A Rainy Night in Midlands

The other week, Shreya and I figured out how rain works, on a particularly bleak rainy day walking out of Woody's. So there's air with some amount of moisture dissolved in it. That moisture is measured in terms of "relative humidity," i.e., how much of the saturation value of water there currently is. Saturation is dependent on one thing only: vapor pressure of water at a given temperature, such that when the partial pressure of water in the gas phase in the air equals that vapor pressure, the air is saturated.

So that's all fine and good, but how does it explain rain? The answer owes to the psychrometric chart, a hideous monstrosity of curves and grids that can probably tell you the answer to the life, the universe, and everything if you say the magic incantation and find the intersection of any one of about twelve tie lines. One especially useful property (only involving about four lines at a time) is if you cool the air enough, you hit a saturation curve and begin condensing water as you cool further. Everyone knows from their friendly 6 o'clock weatherman that a cold front brings precipitation... and now I know why.

Another interesting property is red dye fading at a rate disproportional to other colors of dye. Emily attempted some relativist INTA explanation that "our society has a limited definition of red compared to other colors." I countered with a (help me, God) physics answer of red being close to the end of the visible spectrum. Of course, violet does not experience the same dye as would be expected from also being at the end of the visible spectrum, so there goes my theory. Eventually we settled on the fact that red is the least abundant of naturally occurring colors, so there is most likely an atmospheric reason that our environment is unkind to redness. Anyone know what this is?

Emily has a point, though. As much as I despise thinking in terms of "society," colors are completely subjective. We've got green and blue next to each other on the spectrum. Those are definitionally different colors. But there are (infinitely many) colors between the two of them. Who decides that "forest green" gets called "green," "sky blue" is "blue," and "turquoise" is somewhere in a chromatic no-man's land, neither green nor blue?

Finally, I bought a copy of the Baghavad Gita from some guy on Skiles who was doing yoga and fundraising for something or another. Theology is a wonderful thing, and it pains me to realize that this book is probably number six or so on my List of Books to Read. Maybe I can make some progress over Christmas?


Currently listening: The Many Moods of Christmas, Robert Shaw

3 comments:

Gina said...

Ironic, considering I just dyed my hair red. LOL!

I tried to explain the subjectivness of colors to my Language Arts class one time. LOL I'm sure you can imagine how that went. Granted, it too came in hand with an explanation of relativism, but yeah. LOL I think the subjectiveness comes in the brain's interpretation of said colors/wavelengths of light. My dad and I still argue over the color of the "low on gas" light--as to whether it's orange or yellow. But that's another theory for another day.

Hope you had a merry thanksgiving!

Nick Simmons said...

It must be that time of year. I also dyed my hair red last week.

Don't worry - it was temporary dye, to accompany a themed "Layers Dinner" in which all present wore an absurd number of layers of clothing, sometimes four or five garments in a particular armor slo... body, um, area, and the colored hair gel was an additional, sneaky layer. And all of the food was casserole and stacked desserts and things.

A picture of three of us looked like really bad anime cosplay.

...

Thank you for explaining rain, Matt.

Matt Pavlovich said...

I really, really hope you have pictures of your bad anime cosplay. That is most certainly worth seeing. What, pray tell, was "layers dinner" in association with?

You do realize that you're only getting the bonus associated with one of those pieces of clothing.