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Post by numerouno on Aug 25, 2013 10:30:27 GMT
In dry places like Florida and Arizona you can freeze water when the dry still atmosphere is about 7-12? degrees warmer than the surface the ice builds on. The same principle was used by the ancients to create ice and it is still used today in parts of India where an insulating mat is laid on the warm ground and a pond of water is continually skimmed as the ice builds in the relatively warm dry night time atmosphere Andrew, you're deep into the nonsense area now. The ancients would not have had the artificial cooling below -0C you would need for making ice when your ambient temp is above 0C. There will be no ice forming from nothing if your ambient temp is above 0C, ever. Period.
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Post by numerouno on Aug 25, 2013 10:37:44 GMT
Icefisher: When the ice melts it extracts heat from the plants and will freeze them. You are on the correct track in that application of water is continued until the ice melts off via higher air temp. I can't do the math to show why this happens. I know what happens if this is not done. The plants will freeze at 33f. No! Ice melts at exactly 0C, and the plants will stay at exactly 0C for as long as the melting of the ice continues. It can't "extract more energy" from the plants as they ARE ALREADY AT 0C! You can test this on your own with a small vessel of cold water encrusted with ice with a thermometer in it if you don't believe me. No maths required here, just everyday common sense really. - On the spraying protection in general: if the spraying of water is ongoing, the heat content of the incoming warm water, in relative terms, may keep the area warm enough, if the air is still, as it almost always is, at least here in Finland during summer night frosts.
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Post by numerouno on Aug 25, 2013 10:42:26 GMT
We are not talking about supercooling and water tailored for it. If my wish is your command, as you said,you will keep on searching for a video that shows a thermometer climbing, and warm air being emanating from some freezing water.
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Post by icefisher on Aug 25, 2013 14:38:22 GMT
We are not talking about supercooling and water tailored for it. If my wish is your command, as you said,you will keep on searching for a video that shows a thermometer climbing, and warm air being emanating from some freezing water. Sorry Numno only one fulfillment per wish! You got a thermometer climbing and warm air emanating while the water froze. If you are complaining you could not see the warm air, well buy some better glasses that lets you see the air right in front of your nose. Tailored water? Its H20 what do you think it is?
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Post by Andrew on Aug 25, 2013 14:53:00 GMT
In dry places like Florida and Arizona you can freeze water when the dry still atmosphere is about 7-12? degrees warmer than the surface the ice builds on. The same principle was used by the ancients to create ice and it is still used today in parts of India where an insulating mat is laid on the warm ground and a pond of water is continually skimmed as the ice builds in the relatively warm dry night time atmosphere Andrew, you're deep into the nonsense area now. The ancients would not have had the artificial cooling below -0C you would need for making ice when your ambient temp is above 0C. There will be no ice forming from nothing if your ambient temp is above 0C, ever. Period. Numerouno An object can be cooled to many degrees below the air temperature by radiating thru the warmer dry air to the cold of space or the upper atmosphere. The air immediately next to the radiating surface is going to be fairly cold but air only a meter or so away is going to be much warmer The principle has been tested to cool houses in the USA by linking an air circulation system to the roofs surface. www.fsec.ucf.edu/en/publications/pdf/FSEC-CR-1835-09.pdfStrangely enuf, Florida gets very dry weather and the dry atmosphere has a very poor ability to warm objects at a distance. It is just physics 101 In Finland you can get a day time sky temperature of easily -30C in March, when the sun is shining brightly and the sky is clear of cloud and when the air near the ground is above freezing. Providing the air is dry, heat at the surface will radiate straight thru the warmer near surface atmosphere to heat the upper atmosphere or space. Currently at 18:10 on a warm sunny day in Helsinki the sky temperature above our house is -6C
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Post by numerouno on Aug 25, 2013 15:51:25 GMT
Tailored water? Its H20 what do you think it is? The supercooled water purposefully prepared for the video you linked to was not pure water. You can have the video showing a puff of warm air emanating, the thermometer climbing, or any combination of the two, concurrent with the water freezing. (Provided the emanating warm air is then alternatively evidenced by some other means, like infrared video/photography)! So, supercooled water with tailored contents will not be accepted. The water has to be regular water. The English language phrase "tap water" decribes well the type of water that I mean. - Note to Mr Sigurdur, he can also, symmetrically in fact, apply to the contest by supplying a video in which a body of melting ice spontaneously makes an adjacent (= thermally well-coupled) body of water freeze up. - And, to be fair, I'm not expecting to be hearing from either one of you in the way of any such clips.
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Post by numerouno on Aug 25, 2013 15:54:05 GMT
Currently at 18:10 on a warm sunny day in Helsinki the sky temperature above our house is -6C Andrew, please no any sky temps here. People are confused enough already. If you have seen a real-life freezeup of water occurring when the ambient temp is above 0C and otherwise under normal room conditions, please add your video to my list of extremely improbable videos of Mr Icefisher, and Mr Sigurdur.
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Post by Andrew on Aug 25, 2013 16:02:21 GMT
Currently at 18:10 on a warm sunny day in Helsinki the sky temperature above our house is -6C Andrew, please no ay sky temps here. People are confused enough already. Numerouno you are beginning to sound like you and Icefisher have much in common when it comes to learning what you do not know. Pure water or near pure water can be super cooled. The sky temperature is the measurement you take at the ground using a radiation thermometer or an infra red camera. Dry air has a very poor ability to warm objects at a distance. Therefore if the near surface atmosphere is very dry it has almost no ability to warm objects at a distance and the conductivity of air is very low. Physics 101 says that heat at the surface will be rapidly radiated to the colder sky thru the almost entirely non-emitting dry warm near surface atmosphere.
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Post by Andrew on Aug 25, 2013 16:17:52 GMT
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Post by numerouno on Aug 25, 2013 19:15:41 GMT
Ok, Andrew. Keep them videos a-coming! The present-day Indians no doubt would love to have ice for free in their refrigerators, especially the poorer segment of the population!
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Post by numerouno on Aug 25, 2013 19:26:30 GMT
Pure water or near pure water can be super cooled. Yes, and I just said "it has to be tap water" to mr Icefisher, which is nowhere near pure.
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Post by magellan on Aug 25, 2013 19:49:19 GMT
Pure water or near pure water can be super cooled. Yes, and I just said "it has to be tap water" to mr Icefisher, which is nowhere near pure, that water that is. So it went from this to You could run naked in a mall in sandals and argue with the police you aren't really naked because your feet are partially covered. Just so everyone has an understanding of the science involved, define what tap water is so there is no confusion. Apparently the water used by farmers is not tap water, but is that special distilled (condensed) water. Explain what this chart means taken from biomet.ucdavis.edu/frostprotection/Principles%20of%20Frost%20Protection/FP005.htmlTable 1. Exchanges between latent and to sensible heat. Positive signs indicate that the water is cooling or freezing and the air is warming. Negative signs indicate that the water is warming or evaporating and the air is cooling.
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Post by numerouno on Aug 25, 2013 20:16:01 GMT
Explanation? Again someone who has misunderstood the concept of latent heat.
Just one simple video where one can see the said heat being released, and emanating from the freezing water.
Could it be too much to ask? Surely someone somewhere would have shot one, right?
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Post by sigurdur on Aug 25, 2013 20:23:16 GMT
Numeruno: No video has been done because it is not a rare event. Ever notice frost?
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Post by numerouno on Aug 25, 2013 20:44:12 GMT
Numeruno: No video has been done because it is not a rare event. Ever notice frost? I am not asking anyone to locate videos on farmers under frost in their fields. I'm asking for a video that shows that warm air emanating from freezing water than many here say must exist, in a nice clear room/lab setting preferrably so that I everyone can see and go "gee, just what I told would happen". If it is not a rare event at all, then how come am I seeing no clips?
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