Friday, July 6, 2007

nitpicking the media: of swamp coolers and heat waves

The West has been hot. Hot, hot, hot. Well, except for here; our July weather pattern arrived on Wednesday, and we're having these amazing afternoon thunderstorms. (Well, amazing for now; I'm doing lab work this week.)

In any case, when I saw CNN's headline about the weather (Stifling heat spreads throughout West), I had to check it out and see which West, exactly, was miserable.

As I read the story, this section stood out:

Air conditioners -- and even swamp coolers -- were predictably hot sellers at the hardware store.

"I'm telling you, it has been nuts," said Dennis VanDyke, a manager at Power Townsend in Helena. "The only thing I am getting calls for is air conditioners."

VanDyke said some people prefer swamp coolers, which use a fan and the condensation of water to cool the air, over the more power-hungry air conditioning units.


Ok. Let the nitpicking begin. Key point: it's the evaporation of water, not its condensation, that cools things off. It's all about latent heat: it takes energy to turn liquid water into water vapor, and as the energy gets sucked off to send those water molecules flying away, the surroundings cool. This is actually an important concept. It explains why 90 F is pleasant here and unbearable in New Orleans. It explains why exercise is more pleasant in an arid climate. And it explains very important things, like why hurricanes cool the ocean that feeds them.

What's weirder and more confusing is that condensation actually does the opposite: it warms its surroundings. This seems counterintuitive, especially for people like me who grew up in cold, humid places, and who know how cold dew can feel on the grass (or - shiver - on a tent). But the condensation of water to make clouds heats the air, high up, and can make rising air continue to rise.

So, anyway: CNN, you lose points. Sorry.

Second point: swamp coolers are really, umm, cool. They cool a house by evaporating water - that's it. They use a lot less energy than air conditioners do. They aren't an option for places with high humidity, but in a place where the humidity is often less than 10%, they're great. (I don't have one - I cool my house by keeping shades pulled during the day, and opening windows at night. But I think they're a great concept. Good way to reduce electricity bills, reduce one's carbon footprint, and so forth.)

(Aside: I think I might keep track of little errors in the media. They might make fun exam questions.)

2 comments:

Brian said...

if we don't nitpick the media...who will?

keep it up

tectonite said...

if we don't nitpick the media...who will?

Exactly. And if I can find enough good nitpicks for a section on an intro exam, maybe the exam questions will seem a bit more interesting.