Allegedly, back in the 1930's when Crosley Broadcasting had a waiver from the FCC to operate WLW in Cincinnati, OH at half a megawatt, the brightness of streetlights in that part of town would pulsate slightly in step with the modulation.
You can find more here:
http://www.ominous-valve.com/wlw.htmlEven at 50 gallons the station still puts out a manly signal, allegedly due in part to the Blaw-Knox transmitting tower which is extra wide in the center of its length... And that's supposed to be where the current node in the radiation pattern lives. Phattest part of the tower radiates the phattest part of the RF. Or, at least that's the plan...........