Trees = cold air

[Richard Winder]

In article <29mo7gINNbh1 at eccdb1.pms.ford.com>, goldstro at be0238.be.ford.com (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 be0238.be.ford.com

The upper canopy of tall forest trees intercepts more than half the radiant
energy of the sun.  This percentage often drops to less than 10% by the time
you reach the forest floor.  Wherever the shade from the trees was falling,
the ground would be absorbing/reradiating less heat- air circulating through
there would be cooler.  If the shade was on the pavement, this effect would be
particularly noticable.  I'm not sure where your O2 theory is coming from-
lower greenhouse gas concentration, maybe?  Or less heat conductivity?
Anyway, you probably need a larger area and greater differentials to see such
effects.   -RSW



  RICHARD WINDER                    Title: Visiting Fellow
  Forestry Canada                   Phone: (604) 363-0600
  Victoria, B.C.                    Internet: RWINDER at A1.PFC.Forestry.CA