when the air screams

so we're sitting here watching the vandy-florida college world series baseball game, and the tornado alarms go off. not here - there, in omaha. (omaha! i know, right?) the alarms go off and people start leaving the stands and the players are looking around and the umps are looking around and the umps are like - play ball! - so they continue for a couple more at-bats, but the alarm keeps going waaaoooohhhhh waaaaaoooohhhh waaaaoooooohhhhh. finally here comes the official who is dressed in khakis and a red polo shirt, so clearly he's not an 'ump' per se, but he's got a walkie-talkie in his hand and he just struts right on out there and that's it, everyone leaves the field.

waaaaoooooohhhhh waaaaoooooohhhhh waaaaoooooohhhhh

i thought tornado sirens were automatic, but turns out, not so much. most communities that have the sirens have a network of sensors around the area. the sensors measure barometric pressure, humidity, and static charge in the air, and report these back to central stations where people analyze the results and decide when the environment is right for generation of tornadoes. when the people decide, they turn on the sirens.

right off there, i spot a flaw. people. relying on people to turn on the sirens is a weak link. why can't they be completely automated? weather prediction is still more art than science, i suppose.

these same sirens can be used as air raid sirens, which there is not so much a call for these days. let's hope it stays that way, eh? yes, let's. the sirens can also be used to sound an alarm for tsunami, flood, fire, curfew, other community situations. in haxtun, colorado the siren goes off at 07:00, 12:00, 13:00, and 18:00 everyday except sunday, to signal the time.

mechanical sirens produce sound by using a rotor to drive a fan or fans to push air through specially designed holes. same way clarinets, kazoos, leaking balloons, and voice boxes work -- air forced at a high rate, pressed through holes too small for the air volume. when you squeeze air like that, it screams.

most sirens produce a unique sound - distinct from emergency vehicles - by combining two simultaneous tones, with pitches usually in a 5:6 frequency ratio (an untempered minor third). yes, i throw around terms like "untempered minor third" all the time and if you read my blog more often you would no doubt know that. sheesh.