"Pat Kiewicz" wrote in message
...
Dioclese said:

What I do disagree about it airflow in lowlying areas. Your final
perception is correct, low spot is colder. You have to understand that
heat
is what's being lost, not cold gained. Cold is the LACK of heat energy.
The heat is moving uphill, rather than cold moving downhill

If "cold" was moving downhill, it would have point of origin. Which it
doesn't if the ambient air temperature is warmer that the cold pocket in
the
low spot you indicate.

"Cold" doesn't move, but cold air most certainly does. And cold air
drainage
to low lying areas makes them more prone to frost.

http://www1.agric.gov.ab.ca/$department/deptdocs.nsf/all/agdex9

quote

Cold air drainage
On calm nights, the shallow layer of cold dense air that forms near the
ground surface will tend to flow downslope if the ground is not completely
level. This phenomenon is known as cold air drainage. It has a major
influence on the distribution of minimum temperature, rendering some
areas much more frost-prone than others nearby. The coldest air settles
in depressions commonly called frost hollows or frost pockets, or it
collects in other areas where cold air drainage is obstructed by some
kind of barrier.

On a small scale, the effects of cold air drainage may be visible in the
widely variable frost damage observed within a medium sized garden.
The lowest areas are hardest hit while higher portions may escape all
frost damage. This underlines the importance of considering topography
when choosing garden sites. On a larger scale, entire fields may be
affected. Even if the slopes involved are very gradual, some fields are
much more suited to cold-sensitive and long-season crops than others
nearby.

end quote


--
Pat in Plymouth MI

"So, it was all a dream."
"No dear, this is the dream, you're still in the cell."

email valid but not regularly monitored



Cold air does move down in elevation. Heat moves up. Heat is lost pretty
uniformly on cool, non-windy nights/early morning at the ground surface.
And the coolest air settles in low pockets. Got it, thanks.
--
Dave
Confront and fight Obama zombieism