Mike Griggs said:

> The interesting part of this was that the temperature under
> the snow remained at 32 degrees regardless of air temperature.

I would have expected you to find variation in snow
temperature at different depths.

Regardless, for an unwrapped, uninsulated hive buried by a
snowstorm, the snow certainly will provide some sort of
"insulation", but more (most?) important, it will block the wind.

Bee clusters don't radiate enough heat to even warm the
interior of their hive, so there is not going to be much
"igloo effect" if the hive is buried.  That's a good thing.
Too much heat, and you'd have bees breaking cluster, raising
brood too early, and eating their way to certain starvation
when you thought that they were firmly clustered and safe.

I don't see a screened bottom having a negative impact
in any scenario except those apiary locations that I
would call "Ice Station Zebra", those beyond the natural
range of bees.

...but hives on those waist-high stands could be in serious
trouble if equipped with screened bottoms.  Most winds are blocked
by terrain for hives on cinderblocks or other "low" stands.
I'd be worried about the wind chilling the bee cluster if the
screened bottom was very far off the ground.  What happens to
a ribbon stapled to the underside of a hive on one of these
high stands?  I'd expect it to wave like a flag in breeze.
This would seem to me to be a potential problem, as a very
cold "upstate New York" kind of wind can blow across the screen,
set up an air current between the hive and the outside, and chill
the surface of the cluster down.  (Of course, if this were a
serious problem, the screen would soon be covered with dead bees,
blocking the screen, making it a self-correcting problem, perhaps
before it resulted in a dead-out.)

For seasonal snow cover (not glaciers) on "solid ground", with
air temps below freezing, the temperature would be closer to
the air temp towards the top, and would get warmer (closer to
32F / 0C) as one probes lower.  When air temp is above freezing,
the snow at the surface will be warmer (its is melting), and
deeper snow colder.  There is considerable heat transfer between
the bottom and top of even a layer of snow several feet deep.

Snow and ice crystals themselves aren't always exactly at 32 F,
even when the air temp is.  Air is a lousy absorber of solar
radiation. Snow is better.  Snow may have a very high albedo
and reflective ability, but it absorbs more solar radiation
than the air. Snow and ice can melt in the sun even though
the air temperature is 32 F or slightly below.

When skiing in Europe, one will often be lectured by members of
the blaze-orange jacketed ski patrol about "avalanche potential",
and one of the ominous signs of danger is the "temperature gradients"
within the base snowpack.  If they find scary gradients when they do
their daily measurements, they close entire sides of mountains.


         jim (Who lived in New Hampshire before
               snowblowers were consumer products,
               and, like the eskimos, has 1,000 words
               to describe snow.  Unlike the eskimos,
               all of his words are unprintable.)

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