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  1. #1
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    Default Weak thermocline = Wet hive ?

    Please share your knowledge of thermodynamics.
    Cheers,
    Drew


    p.s. If anyone knows any entomologists or physicist/beeks could you please get opinion on thread. I'm dying a slow and painful death here
    Last edited by Maryland Beekeeper; 01-14-2013 at 02:23 PM.

  2. #2
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    Default Re: Weak thermocline = Wet hive ?

    From other forum:

    Quote from: Maryland Beekeeper on January 12, 2013, 10:15:37 PM
    Got any pics of condensation in a honeybee hive ?

    Reply:
    They make any sense. Idea is avoid condensation, not to make it.
    bees make condensation regardless ... this is about where it happens
    if it occurs inside the insulated space below the bees you get 10% heat back

    Re: Condensation in an observation hive
    Reply #34 on: Today at 01:51:47 PM
    Reply with quoteQuote Modify messageModify

    DING ! DING ! DING ! WINNER ! WINNER ! CHICKEN DINNER ! applause

    Also, (and more importantly), if it occurs in insulated space below bee's, you have dry B's !
    Cheers,
    Drew
    Last edited by Maryland Beekeeper; 01-14-2013 at 04:05 PM.

  3. #3
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    Default Re: Weak thermocline = Wet hive ?

    From other forum:

    No question should ever be considered unreasonable - the only unreasonable aspect of this thread are the responses from ... and his parrot, who cannot get their heads around a perfectly sound enquiry.

    Warm air rises, and cold air descends - therefore the formation of a thermocline is always possible. But I would suggest that the existence of a thermocline within a beehive is highly unlikely ... for 2 reasons.

    The first is the activity of the bees themselves. Wherever there is active circulation (often due to the cluster being located towards one side), there is unlikely to be stratification of thermal layers.

    The second is that a vortex is created near the entrance to any occupied hive, due to the movement of air through a narrow space. (Clearly this would not apply where OMFs are fitted.) Such vortices would also 'stir the air'.

    The only time I could envisage a thermocline being created would be when the bees are very tightly and centrally clustered, and when the upper part of the hive is 100% sealed. But the breaking of cluster would soon mix the air, thus destroying any temporary stratification.

    At least, that's how I see events within the hive. But I could always be wrong !


    Thermoclines are more usually associated with large outdoor expanses of water, where the water is heated (by the sun) from above. Warm water rises and the cooler water gradually migrates downwards (just check your domestic hot water tank) - thus creating the thermocline. I have often experienced these when diving in the Med - it's like moving through an invisible curtain between an oven and a fridge. Very strange.

    Having said that - an immersion heater does heats the water from below, and a thermocline is most certainly created within a hot water tank (but it's a tank which isn't stirred), so it's far from being a stupid issue to raise.
    Me:
    I to am a scuba diver, and sky. My contention would be...... ready for it ? The atmosphere is static ! remember combs now, can you visualize how the heat would disallow condensation above thermocline ? Smile The honeybee hive is natures perfect distillery ! Smile
    _Me
    Of course it could be wishful thinking but, if you go back, re-read Langsroth, Huber, I'm working thru Swammerdam now, the clues are there. They saw the thing, just, like all since, missed the significance. They didn't understand thermocline
    Me
    Go, look @ your honeybee organism, again for the first time,........ think upside down moonshine still,..... think hermit crab.....can you see it now ? Smile

  4. #4
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    Default Re: Weak thermocline = Wet hive ?

    Insufficient context to really know what the debate is here, but a couple of thoughts.

    1. Most hives should not contain a real thermocline (i.e. a horizontal plane with warmer air above and cooler below). More likely the air in a hive will form a convection cell. Air within the cluster is 95 degrees. This warm air will rise. Rising air will cool through contact with the cooler top (with moisture condensing out), then sink along the walls and eventually flow back through the cluster where it will pick up heat and moisture. Insulation will slow the rate of convective flow but will not stop it. The only way to stop cluster-driven convection entirely would be to heat the hive from the top, which could happen with a black roof in sunny weather or if another hive is stacked above.

    2. An insulated tall hive with a bottom entrance and the cluster in an upper box could form a thermocline. In this case we would have a convection cell in the upper boxes above a pool of colder air in the lower box(es). Such a situation would not necessarily be good or bad, but as all of the moisture would stay in the upper convection cell there could still be plenty of condensation and dripping on the cluster.

    3. Moisture will condense on any surface cooler than the dewpoint of the air in contact with it. In an un-insulated hive, most of the moisture condenses on the top immediately above the cluster. With an insulated top, more condensation will occur on the walls. It should be possible to selectively condense moisture away from the bees by insulating the top and providing a very poorly-insulated wall (e.g. glass in an observation hive). Condensing moisture entirely below the bees will be a challenge, as placing a cold surface at the bottom will inhibit convection (cold air will pool against this surface, as in #2 above). I could see it working though with well-insulated walls and top, and especially if the bees actively mix the air to substitute for convective processes.

    This year I solved my moisture problems with wood-chip quilts (http://www.honeybeesuite.com/how-to-...ngstroth-hive/). Moisture condenses on the top but is caught by 3" of wood chips so doesn't drip down on the bees. Seems to be working great so far.

    Mark
    Last edited by Luterra; 01-14-2013 at 04:09 PM. Reason: did some more thinking

  5. #5
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    Default Re: Weak thermocline = Wet hive ?

    That you can't imagine is why you cannot see, I have a glass hive/shell, and have seen, but have only now come to understand, .....perhaps, ......we shall see
    Last edited by Maryland Beekeeper; 01-14-2013 at 04:41 PM.

  6. #6
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    Default Re: Weak thermocline = Wet hive ?

    Quote Originally Posted by Maryland Beekeeper View Post
    That you can't imagine is why you cannot see, I have a glass hive/shell, and have seen, but have only now come to understand, .....perhaps
    What have you seen? What cannot I see? If you are going to bring over a discussion from another site, please don't assume that we are all readers of that site.

  7. #7
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    Default Re: Weak thermocline = Wet hive ?

    I didn't mean to imply that assumption. I think what you will see if you build a glass hive is that the water condenses below the thermocline.

  8. #8
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    Default Re: Weak thermocline = Wet hive ?

    Ah I see. Indeed as I am typing this in a humid house, I see condensation on the lower half of all of the windows. I still think the phenomenon is better explained by simple convection than by existence of a thermocline.

    hivecirculation.jpg

    Black = air temperature. Green = air dewpoint. Other colors = inside glass/surface temperatures. Blue arrows = convection currents within the hive.

    Water will condense on the coldest surface exposed to convection within the hive. In your hive, this is the lower part of the glass sides. The line below which condensation occurs represents not a thermocline but rather the line below which the inside surface of the glass is colder than the dewpoint of the inside air. The reason the lower part of the glass is colder is due to the convection currents; warm air rising off the cluster heats the upper surface warmer than the dewpoint, preventing condensation there.

    As an experiment, I bet if you wrap a warm blanket around the walls, you will discover that condensation is now occurring primarily on the top. Without condensation on the colder walls, the dew point inside the hive will rise above the temperature of the ceiling glass, and water will condense there.

    A thermocline implies absence of mixing. If there is no mixing, how could moisture be transported from the warm cluster to the area where you are seeing condensation?

    Mark

  9. #9
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    Default Re: Weak thermocline = Wet hive ?

    Mark,
    Very close, and indeed the organism is capable of that action, that is how it distills honey, gets water, ect..It is also capable of turning those honeycombs into a blazing hot/dry radiator, without, any air movement, IMHO. Do you have to flap your arms around to generate heat ? Try yoga In other words Apis can,......boil, the moisture down/out, if ..... the hive is sealed, or close to it.
    Cheers,
    Drew
    Last edited by Maryland Beekeeper; 01-14-2013 at 07:51 PM.

  10. #10
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    Default Re: Weak thermocline = Wet hive ?

    Quote Originally Posted by Maryland Beekeeper View Post
    In other words Apis can,......boil, the moisture down/out, if ..... the hive is sealed, or close to it.
    Ok, so where does the moisture start to condense in a high density (100g/litre) polystyrene hive, sealed at the top?
    Last edited by Rolande; 01-15-2013 at 03:27 AM.

  11. #11
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    Default Re: Weak thermocline = Wet hive ?

    Below thermocline, if your hive was upside down aquarium, under certain conditions, you would see a horizontal plane,...... defined, by a line of condsensation.
    Last edited by Maryland Beekeeper; 01-15-2013 at 09:12 AM.

  12. #12
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    Default Re: Weak thermocline = Wet hive ?

    Quote Originally Posted by Maryland Beekeeper View Post
    Below thermocline
    Not at the point of the hand holds where the poly has less thickness then?

  13. #13
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    Default Re: Weak thermocline = Wet hive ?

    clues ?

    http://search.yahoo.com/r/_ylt=A0oG7...206/2/353.full

    http://chopwoodcarrywaterplantseeds....densation.html


    http://ts1.mm.bing.net/th?id=H.48975...58276&pid=15.1


    http://search.yahoo.com/r/_ylt=A0oG7...a_pictures.php

    p.s. I believe that one infra-red depicts a winter cluster, that air is not moving. The thermal layers are visable. The red holes are difference in temp. between out and in. Can you see that no moisture could condense in there ? Equally important, no vertical heat loss because no air loss ? (false, but suits our purpose).
    Cheers,
    Drew
    p.s. Remember you are looking @ 2D slice.
    p.s.s I don't know anything about that pic. It does match perfectly how I see things. A couple more like it and it might be time to start new thread, "Thermohive:Construction"
    p.s.s
    Last edited by Maryland Beekeeper; 01-15-2013 at 10:03 PM.

  14. #14
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    Default Re: Weak thermocline = Wet hive ?

    Moisture comes from the cluster (from water in the honey). Condensation forms on the coldest surface inside the hive. Moving that moisture from the cluster to the point of condensation requires air movement. Therefore we have convection. Convection is driven by thermal gradients.

    There is no thermocline, if a thermocline is defined as a sharp boundary between air layers that do not mix.

    Mark

  15. #15
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    Default Re: Weak thermocline = Wet hive ?

    Mark,
    I think I agree with most of what you say ? The movement of moisture through thermal layers is beyond me. Each layer has lower dew point ? Refer back to Infra red pic, I agree the cluster is warm and moist, the yellow going to holes is not as warm, the red at holes, I would surmise, is vapor giving its heat and condensing, yes ?
    Let me think of better way to say, or get rescued by thermodynamics professor Hopefully latter.

    -the other pic, the hives, can you see how a thermal layer protects them completely ? The heat from those clusters is heating the whole hive. My guess would be, that is with top ventilation(thus the visible heat rising from clusters), can you imagine how much more efficient if you seal the roof.

    p.s. The many edits tell me I am out of my depth Also I see my description is poor, I should be saying thermal layers not thermocline. Thank you Mark
    Last edited by Maryland Beekeeper; 01-16-2013 at 12:58 AM.

  16. #16
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    Default Re: Weak thermocline = Wet hive ?

    I think I understand what you are saying. Conventional wisdom is to provide top and bottom entrances. This causes upward airflow through the hive allowing moisture to escape, but allowing heat to escape along with it. You're suggesting it might be better to seal (and insulate) the top, causing moisture to condense on the sides and keeping the heat in.

    A closed convection cell (i.e. natural airflow in a sealed or one-entrance hive) will generate much slower airflow than an open convection process (bottom and top entrances, or SBB with top entrance). This is because in a sealed chamber, warm air pools at the top and sinks fairly slowly as it is cooled by contact with the top and sides. Less airflow through the cluster should mean less heat loss, less stores consumed.

  17. #17
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    Default Re: Weak thermocline = Wet hive ?

    Mark,
    Going back thru thread I think I sound like an idiot and owe you an apology for it. Thank you for bearing with me
    Drew
    p.s. Your description, to me, sounds, fantastic !... I'm not sure that says much Closed convection cell is now the word of the day ! Off to google
    Last edited by Maryland Beekeeper; 01-16-2013 at 02:55 PM.

  18. #18
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    Default Re: Weak thermocline = Wet hive ?

    Mark,
    You toy with me This coincidence(?) gave me a chill I will be happy to admit to you.

    http://search.yahoo.com/r/_ylt=A0oG7...ell-convection

    Fess up ! Please
    Drew

    p.s. I am ready for a rest, for even if this is the top of a rise, I suspect it will not be the highest along the road.
    Last edited by Maryland Beekeeper; 01-16-2013 at 03:42 PM.

  19. #19
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    Default Re: Weak thermocline = Wet hive ?

    Convection (in both open and closed systems) occurs on all scales, from beehives to houses to the atmosphere. I'm not sure an article describing open and closed convection cells at an atmospheric scale will have much relevance to beehives.

    Beehives lose heat through conduction (heat transfer through the walls and roof) and convection (warm air leaving the hive). A closed convection cell (i.e. a hive with no top entrances or vents) will still have convection occurring inside, but all heat loss will be through conduction.

    Less conduction loss is almost always a good thing (i.e. stacking hives together, wrapping for insulation). A "good" amount of convective heat loss is a balance between heat conservation and air/moisture exchange.

    Natural beehives in tree cavities generally have a single, smallish entrance, very thick ceiling insulation, and thinner wall insulation. I would expect that in natural cavities most moisture condenses on the walls and flows to the bottom of the cavity, while the entrance is sufficient for air exchange. Managed beehives are in general less well-insulated, so probably require more calories per bee to overwinter.
    Last edited by Luterra; 01-16-2013 at 08:50 PM.

  20. #20
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    Default Re: Weak thermocline = Wet hive ?

    Me either. But I'm a dreamer I see honeycomb in the sky and see no reason not to expect Apis could recreate in hive if it were to advantage That cluster pic has got me thinking weber grill hive, reflect heat evenly

    p.s. I see upside down infra red pic of bhive

    http://en.wikipedia.org/wiki/File:Ra...Convection.png

    Drew
    p.s.s Relevant ?
    p.s.s.s Conduction, lessened with increased reflectivity(?) of interior ?
    Last edited by Maryland Beekeeper; 01-17-2013 at 04:41 PM.

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