Last Thursday morning I was riding to work and I noticed what I understand to be "chemtrails" streaked across the sky. To me, it seems that these "clouds" are appearing more frequently. Is there an official explanation as to what these are? —J. Seville

Chemtrails, for those of you fortunate enough not to have heard of them, are the subject of a crack-pated conspiracy theory that manages to combine a hippie's mealy-mouthed whining about toxins with a tea-party activist's unhinged ravings about the federal government. If your idea of a good time includes sharing a tent at the Rainbow Gathering with Ann Coulter, you'll love chemtrails.

Here's the theory: You know those condensation trails behind flying planes? Where the water vapor in the plane's exhaust condenses into droplets in the cooler air? And then those droplets gradually evaporate—quickly in dry air and more slowly in moist air, in accordance with principles well understood by any moderately bright 10-year-old?

Well, according to chemtrail theory, sometime in the mid-'90s the federal government changed the laws of physics such that the combustion of hydrocarbons stopped producing H2O and starting producing some deadly combination of HIV, dioxin and Strontium-90.

No one profited by this, mind you—it was an experiment to end global warming. Because God knows stopping global warming has always been Washington's No. 1 priority.

Of course, they were able to keep this largest-in-history scientific program completely secret. After all, everyone in government can always be relied upon to keep each others secrets, no matter how politically advantageous it might be to spill them.

To sum up: it's bullshit. The normal trails just last longer in humid weather. (Yeah, yeah; I know what you're thinking. But if I am in on it, where the hell's my check?)