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Date: | Sat, 19 Dec 2020 06:55:47 -0800 |
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> Not sure what proof folks want on lower entrance air movement in a dead
quiet hive (no fanning taking place). IR images clearly show heat. My lower
entrance vs outside (delta T) shows a very nice linear relationship (some
variability however values are well contained within a range). The stack
effect heat loss/ventilation calc references that Alexander shared a few
days ago apply here also.
Etienne, I'm not fluent in "Engineerese," so I'm curious about your
statement that "no fanning takes place," since that is contrary to what
some other researchers have found.
In warm temps, Heinrich showed how a swarm passively vents out the top, but
for a tight winter cluster, which has so little diffusion between it and
the outside atmosphere that oxygen and CO2 concentrations differ greatly
from the outside air, it appears that the bees actively control
ventilation, forcing air by fanning out of the bottom of the cluster.
So my question is whether your sensors would pick up such brief bursts of
air venting. Your graphic shows that there is a temperature gradient below
the cluster in the single story hive. Could that be an artifact of brief
"exhalations"?
Randy Oliver
Grass Valley, CA
530 277 4450
ScientificBeekeeping.com
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