Plumbing Vent...why so tall?

[Larry D. Kage]

Originally Posted by lewens

Get the thing up into a good wind and you might get a venturi effect across the top of it and really reduce the effectivness of the vent to draw air.
Larry

Up high enough, it has the potential to freeze shut with enough moisture escaping.

[Kenton H. Shepard, CMI]

Gypsies, actually... was the term he used. Said he'd done some research into it. I did a ride-along with him and we were in a tract. He pointed out a home with a vent about like the one in your photo. He said they typically add a whole section.