In article
,
Chris wrote:

On May 5, 7:51*pm, Billy wrote:
In article
,



*Chris wrote:
On May 5, 12:38*pm, Billy wrote:
In article
,

*Chris wrote:
On May 5, 1:57*am, Billy wrote:
In article ,

*Jeff wrote:
In a moderate climate (Oregon, about 100 miles from the coast),
how
practical would it be to try to raise vegetables year-round in a
greenhouse?
- Jeff
www.reframer.com

Do you have full sun all day?

In OREGON???

Some of my worst sunburns came on overcast days.

Sure- same here. But sunburn comes from ultraviolet radiation, and
that doesn't add too much in the way of heat.

???? It's a greenhouse! Greenhouses have an effect. True the interior
temp will be proportional to the exterior temp, but the greenhouse will
be warmer.

My point was that UV radiation pierces cloud cover, but infrared does
not. UV does not make you warm. That's why it's easy to get a sunburn
on a cloudy day- you never feel your skin warming up. IR is what heats
up a greenhouse. And I think you underestimate the very, very few
sunny days western Oregon experiences through the winter. And if Jeff
is indeed in the foothills of the Cascades, he's going to have _much_
colder weather there than what I had in Corvallis.

A greenhouse is a structure with different types of covering materials,
such as a glass or plastic roof and frequently glass or plastic walls;
it heats up because incoming visible solar radiation (for which the
glass is transparent) from the sun is absorbed by plants, soil, and
other things inside the building. Air warmed by the heat from hot
interior surfaces is retained in the building by the roof and wall. In
addition, the warmed structures and plants inside the greenhouse
re-radiate some of their thermal energy in the infra-red, to which glass
is partly opaque, so some of this energy is also trapped inside the
glasshouse. However, this latter process is a minor player compared with
the former (convective) process. Thus, the primary heating mechanism of
a greenhouse is convection. This can be demonstrated by opening a small
window near the roof of a greenhouse: the temperature drops
considerably. This principle is the basis of the autovent automatic
cooling system. Thus, the glass used for a greenhouse works as a barrier
to air flow, and its effect is to trap energy within the greenhouse. The
air that is warmed near the ground is prevented from rising indefinitely
and flowing away.

Although there is some heat loss due to thermal conduction through the
glass and other building materials, there is a net increase in energy
(and therefore temperature) inside the greenhouse.
---
And let me add that ANY electro-magnetic radiation (infared or
otherwise) that is absorbed in the greenhouse will lead to excitation of
molecules, which will return to a lower energy state by giving off heat
(molecular vibration, or radiation of longer wavelengths) to its
environment, in this case, the greenhouse.

"Last year, 43 people fell off their bicycles in Corvallis- and
drowned."
(Popular t-shirt at OSU)
Darwin at work.


Chris




Melons and corn may not
grow in a green house during his winter, but with nothing physical
blocking his sunlight, he should be able to grow lettuce, kale, chard,
broccoli, cauliflower, and maybe even peas.

Indeed.

Heh. I went to Oregon State, in Corvallis. Three of the 4 years I was
there, it on September 1st the temperature dropped to 50 degrees and
it started to rain. The temp never changed and the rain never stopped
until May 1st.

OK, an exaggeration, but not much of one. Now, Corvallis is about 50
miles from the coast, so it sounds like Jeff is somewhere in Cascade
Range. You can count on more snow up there than in the Willamette
Valley.

Jeff, it really depends exactly where you are. I knew people near
Salem who raised fuchsias year-round, and they probably are less
hardy
than some vegetables. Also, it depends what you want to grow. I'd
give
up on melons and cucumbers, but lettuce, broccoli, cauliflower, peas
might all do well.

Chris

"Gardening adds years to your life and life to your years."
- Anon
--
- Billy

Bush's 3rd term: Obama plus another elective war
Bush's 4th term: another Judas goat

America is not broke. The country is awash in wealth and cash.
It's just that it's not in your hands. It has been transferred, in the
greatest heist in history, from the workers and consumers to the banks
and the portfolios of the uber-rich.
http://theuptake.org/2011/03/05/michael-moore-the-big-lie-wisconsin-is-broke/