Cloud streets are lines of clouds that form in unusual conditions.
The most favorable conditions for their formation occur when the lowermost layer of air is unstable, but is capped by an inversion-by a stable layer of air. This often occurs when upper air is subsiding, such as under anticyclonic conditions, and is also frequently found when radiation fog has formed overnight. Convection occurs below the inversion, with air rising in thermals below the clouds and sinking in the air between the streets.
There's a video of a plane flying over them after the jump, and I think you'll agree that these clouds are clearly the work of an evil sorcerer. Why the hell he's spending his time making cloud streets is anyone's guess, but I have a sneaking suspicion it has something to do with mobilizing his dragon army. I swear, those dragons are so freaking stupid they'd get lost without a line to follow. He needs to start breeding those dumb bastards with TomToms in their brains.
Continue for the video.
Video: Cloud streets [pinktentacle]