The fog only comes from one row. The other tubes provide a laminar column of air. Think of it like a sandwich. The outer layers of air are moving in the same direction and speed as the inner (fog) layer. The air mass is also very uniform; coherent (for lack of a better term). This protects the fog layer and keeps it moving in a straight line, like a curtain. This fogscreen can be raised up to about 10 feet and the fog will stay in a sheet all the way down to the ground, creating a screen that can be walked through. The fog source is ultrasonic foggers so, there is no duty cycle. I can run this thing all night. No duty cycle, no heat, and nothing but water vapor. The water tank where the foggers sit is auto-fill so, it will run all night when hooked to the tap without needing to be tended to.