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a heating puzzler (sort of)

Steve Ebels_3
Steve Ebels_3 Member Posts: 1,291
I always liked that story, in the book of Judges chapters 5&6 I think. It's all about trust. It's not about dewpoints.

Comments

  • james barnett
    james barnett Member Posts: 8
    a hvac puzzler (sort of)

    I have a carport in my driveway for one car. No walls, just roof. I have two cars, both are the same model, same color (if you find something you like...) So when I wake up in the morning after a clear night, maybe a little wind, maybe not, the car in the carport is dry, the car in the driveway is has dew over it. What's up with that?
  • Floyd_12
    Floyd_12 Member Posts: 3
    Did you ....

    pray like Gideon????

    Floyd
  • bob_44
    bob_44 Member Posts: 112
    Guess

    This is just a guess. The car in the drive can see the night sky and looses more heat than the car in the car port. The carport acts just like a cloudy night. So the surface of the car in the drive is at or below the dew point temperature of the air and the surface of the car in the car port is above the dew point temperature. bob
  • Steve Ebels_3
    Steve Ebels_3 Member Posts: 1,291
    What about

    The roof of the carport? Wet?
  • Empire_2
    Empire_2 Member Posts: 2,343
    All about temp

    The car that is on the outside of the carport is cooler than the other one. Not by much, but cooler. Moisture is condensing on the cooler surface. That car port is keeping the other car warmer. Think of cloud cover in your area...At night when there are clouds, it will be a-little warmer than it would be on a clear night. Ask your weather guy....
  • Dave_22
    Dave_22 Member Posts: 232


    Have you ever switched cars?oes the same thing happen to the other one?
  • Steve Paul
    Steve Paul Member Posts: 83
    DEW IT OR DON'T IT

    Temperature is the culprit. The surface of the car outside of the carport is cooler than the one in the carport. The surface is reaching the Dew point and forming condensation from the miosture in the air. The car inside the carport is being kept somewhat warmer from the building radiating heat from normal heat losses and from acting like a heat sink - absorbing heat during the day and radiating at night.
  • two words

    radiant cooling

    the problem would have been less if it had been cloudy that night.
  • hr
    hr Member Posts: 6,106
    Most nightly news and weather

    stations will post the dewpoint. With this info you could probably predict which mornings will provide dew.

    hot rod

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  • ALH_3
    ALH_3 Member Posts: 151
    Deep Space

    has a temperature of approximately 3 Kelvin. The carport doesn't let the car underneath see the sky. Therefore it's surface temperature is more nearly the ambient temperature. The upper surface of the car that's not underneath the carport is colder due to the radiant cooling of the night sky.

    -Andrew
  • james barnett
    james barnett Member Posts: 8


    very impressive. nearly everyone got it exactly right. this was a weather puzzler that was on some weather site, and as I recall there were no correct guesses for a while. I couldn't figure it out. the night sky acts as a big heat sink.

    James
  • Mark Eatherton1
    Mark Eatherton1 Member Posts: 2,542
    Picture this....

    The actual efect of night sky reradiation as studied at the Eatherton Research Center for Hydronical Studies...

    Enjoy!

    ME

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This discussion has been closed.