Trees = cold air

wildung at wildung at
Thu Oct 21 14:23:22 EST 1993

In article <29mo7gINNbh1 at>, goldstro at (Mitch S. Goldstrom) writes:
> I have a bet to settle with a colleauge, so I thought that I would
> consult the experts.
> When driving by a cluster of trees in a convertable, the air temperature
> seem to drop a few degrees.  I postulated that this was due to the trees
> giving of oxygen.  He thinks I am crazy and gave me some nonsense about the
> pavement and big-city insults.  Who is correct?
> Thanks in advance,
> -Mitch Goldstrom
> goldstro at

I'm guessing you think O2 is responsible for cooling since CO2 is noted as a
green house gas.  I have to side with your friend and roll my eyes.  This
effect is small and only detected on large scales.  I do think the previous
answers have relied to much on plant canopys intercepting energy (shade).  I
believe you would easily have been able to tell if you had driven in or near shade. 
In our little corner of eastern WA we grow spring and winter wheat.  The winter
wheat ripens earlier than the spring wheat and thus dries up sooner.  Being a
motorcyclist I can assure you that I can tell the difference in air temperature 
between a spring and winter wheat field.  No canopy effects here.  Plants
evaporate water to keep cool, and at least some of what you are feeling is
cooler moister air.  Our stands of trees here usually occur in small drainages, 
Don't discount the effect of cool air sinking into even small drainages on
still evenings.

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