Venting a clothes dryer up and through the roof has been a popular practice in the South for some time as most homes are on a concrete slab and the laundry room has been located within the interior of the floorplan. Hot air rises, so no additional forces are needed to vent up versus out or down. Building codes control the length of run and the number of elbows but at present do not govern the specifications of wall and roof terminations; likewise, there are numerous designs and minimal design features that speak to the efficiency of the vent design.
This video provides some compelling results with an actual dryer blower unit while testing four roof terminations. The video is an educational presentation that applies to any home owner with a clothes dryer, and is worth the “watch”.