I have observational evidence. I went out last night with 10x42 binoculars, right after twilight and before moonrise. I swept around for globs, nebulas, and galaxies, and after M83 decided to see if I could find M104, low to the west.
I looked at Corvus, and the northern half of the constellation, where the galaxy is, was awash in light pollution! I looked at the western horizon and saw the small light dome from the town 37 km away, glowing up to about 10 degrees altitude, as usual. But that was not the source of my LP. Corvus was about 30 degrees to the south of it, and right on the edge of the zodiacal light, which formed a funnel of glowing sky pouring out of the zodiacal band, which itself crossed the sky all the way to the Sagittarius Milky Way. It was bright enough to make the Sombrero galaxy disappear, even though I had just easily seen M83, of lower surface brightness and also low in the sky.
I measured with my fist at arms length. The town's light dome was visible up to about 10 degrees. The zodiacal light was glowing with equal brightness to at least 30 degrees above the horizon, with the band carrying the glow in a narrow lane past the zenith.
I also noticed the LP effect of the zodiacal band last month, looking at M33 pre-dawn. In order to hold it comfortably in direct vision, I had to block out both the Perseus Milky Way below and the zodiacal band to the east with my hands.
This is an effect that seasonally degrades the view of all sorts of famous DSOs near the ecliptic, like the galaxies in Leo and Virgo, the Eskimo planetary, etc.
Edited by Araguaia, 19 August 2019 - 06:15 AM.