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Discussion Starter · #1 ·
I created an experiment that shows the solar gain a hive can be subject to in a very short amount of time, but the pics will not upload for some reason.
In the mean time..... how much solar gain (in degrees) do you think is possible in 30 seconds?
 

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I'll qualify my answer with it depends... It depends on time of year and distance to the sun, time of day as it relates to the "thickness" of the atmosphere, cloud cover, air temperature, angle of exposed surface relative to sun, specific heat of the object, color of object...etc.

I think there are an awful lot of variables. With that said, I wrapped my hives and am happy to have done so. You and I are at very similar lattitudes and have similar weather. I'm rather curious about your results.
 

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I often kill myself. It's the conflict between the engineer and the *******. One wants quantified explainations of methods and results, while the other says "Hey, I'llbet you I can make this "something" out of nothing"

I'll go for a surface temperature increase of about 3.5degrees.
 

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As you conduct this experiment, perhaps you could also make some night-time measurements.


Black surfaces radiate more heat in the dark compared to white surfaces (black loses heat more quickly than white surfaces), but some here find that concept difficult to grasp. :lookout:
 

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I am currently running a solar gain experiment, too. The hives have been set up, but I wanted to get a full day worth of results before posting the photos and data, and hope to have the thread started sometime after this weekend.

I can say that at the end of a sunny day:

A hive completely shielded from the sun (i.e. 0 solar gain) had an interior air temperature of 64.4F (same as ambient air temp);
A natural wood-finish hive with no wrapping material had an interior air temp of 72.1F
A hive wrapped in Colony Quilt material had an interior air temp of 76.5F; and
A hive wrapped in a Bee Cozy had an interior air temp of 69.3F.

I don't have roofing paper in my test at this point (not enough thermometers).

These numbers are for empty hives, i.e., no bees to generate heat and no frames with honey to act as a heat sink. Each of the 4 hives consist of three 8-frame mediums with a top and bottom entrance, a Honey Run Apiary insulated inner cover with 2" of rigid pink foam, and a standard sheet metal clad telescoping cover.

More info to follow in a new thread after the weekend . . .
 

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Just for the record, the solar gain for a full hive in 30 seconds is going to be virtually zero.

SURFACE temperatures on the outside of the hive may go up a degree, but I doubt a full hive would see much of an internal temperature rise in only 30 seconds even it you put it in an oven.

Not saying the black won't help warm the hive during the day, just that I don't think the gain over so small of a timeframe would be in any way meaningful.
 

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Discussion Starter · #10 ·
Just so it's clear... it is the surface temp of the tar paper that this experiment shows the reults of. This in essence, will increase the internal hive temp over time exposed to the sun. Any type of heat gain especially in these temps is a good thing.
 

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I normally put tar paper at least covering my brood boxes. I heard somewhere in the past it can keep the internal temp around 40f when it is freezing out and allow them to move around and feed. This year I did not wrap any, and did not observe a noticeable difference - though it was not nearly as cold here as it usually is. My 18 colonies didn't even touch their winter stores.
 

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Just so it's clear... it is the surface temp of the tar paper that this experiment shows the reults of. This in essence, will increase the internal hive temp over time exposed to the sun...
Internally, I would venture to say No Change since wood & air are not good conductors of heat.
 

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Just so it's clear... it is the surface temp of the tar paper that this experiment shows the reults of. This in essence, will increase the internal hive temp over time exposed to the sun. Any type of heat gain especially in these temps is a good thing.
That's what I thought you were referring to, just the surface of the tar paper. I still stand by my earlier guess.:)
 

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As you conduct this experiment, perhaps you could also make some night-time measurements.


Black surfaces radiate more heat in the dark compared to white surfaces (black loses heat more quickly than white surfaces), but some here find that concept difficult to grasp. :lookout:
Ok I'll bite, I don't think the color of a "black body" in the physics argument of radiation if both surfaces are the same temp during the time frames of the measurements makes any difference. Now the black surface should be at a higher temperature if it's been in the sun all day long that the white surface so the IR would be greater to begin with so where's the beef in what the color the surface is or isn't? It's been a long time since I studied this stuff in grad school.
 

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I would believe the 25f increase in general. Last year my hives were a lot more active and had more bees than they do now - but my survival rates didn't change, they actually got better, and I didn't have to constantly refill their emergency feed.
 
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