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Post by rmc on Jul 21, 2016 22:24:52 GMT
Gallium has a known melting point of 29.76 Celsius, and there is a generally-accepted notion that a 'feels like' temperature can be greater than the ambient air temperature when dew points are just right, such that it may feel 3 or 4 Celsius more than the actual air temperature.
Does it make any sense to try and melt Gallium using its melting point in the form of a feel-like temperature rather than an actual air temperature?
And if a feels-like 29.76 Celsius actually ends up melting Gallium, doesn't that confirm that feels like temperatures are actually every bit as real as regular air temperatures?
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Post by GTCGreg on Jul 21, 2016 23:10:56 GMT
Metals don't "feel". It's melting point is what it is and will not change based on how a human "feels" about it.
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Post by rmc on Jul 21, 2016 23:21:52 GMT
So, if humidity turned out to help melt the metal when the actual air temp was around 28 C, that would be unexpected.
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Post by GTCGreg on Jul 21, 2016 23:25:32 GMT
It would be unexpected by me, anyway.
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Post by the light works on Jul 22, 2016 1:32:37 GMT
my understanding of "feels like" temperature is that you have to have a body that is generating heat and requiring ambient cooling (or warming) to be comfortable. in that case, a change in humidity changes the rate at which the body sheds or builds heat, and makes a difference in the perceived temperature.
with that, a metal might heat or cool more rapidly with a change in humidity, but if ambient temperature is below melting temperature, no amount of humidity will change that.
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Post by craighudson on Jul 22, 2016 8:28:54 GMT
If the feels-like temperature affects the melting point of a metal, wouldn't it also affect thermometer readings, which means that it is the actual temperature?
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Post by GTCGreg on Jul 22, 2016 13:39:38 GMT
The "feels like" temperature is a combination of actual thermometer temperature, wind speed and relative humidity. Temperature and windspeed are independent parameters. Relative humidity will change with changes in temperature, but the temperature will not change as a function of the other parameters.
The only time when humidity can change the temperature is if evaporation is taking place. For example, on a hot, very dry day, the actual temperature of your skin can drop due to the evaporation of sweat. This is part of your body's natural cooling system. The ambient air temperature is not changing, but the surface temperature of your skin is.
On a very humid day, the evaporation of sweat is reduced, so your body feels hotter because it actually is hotter. A piece of metal is subject to these temperature changes caused by evaporation, because a piece of metal doesn't sweat. Now if you were to spray some water on that piece of metal, even if the water was the exact same temperature is the surrounding air, the temperature of the metal would actually drop below the air temperature due to the evaporation of that water. But again, the actual ambient air temperature is not going to change.
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Post by the light works on Jul 22, 2016 13:58:09 GMT
The "feels like" temperature is a combination of actual thermometer temperature, wind speed and relative humidity. Temperature and windspeed are independent parameters. Relative humidity will change with changes in temperature, but the temperature will not change as a function of the other parameters. The only time when humidity can change the temperature is if evaporation is taking place. For example, on a hot very dry day, the actual temperature of your skin can drop due to the evaporation of sweat. This is part of your body's natural cooling system. The ambient air temperature is not changing, but the surface temperature of your skin is. technically, the ambient air temperature can change, as the evaporation is an endothermic process. but using a human as an evaporative cooler is not going to cool any significant amount of space. |
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Post by GTCGreg on Jul 22, 2016 14:06:12 GMT
The "feels like" temperature is a combination of actual thermometer temperature, wind speed and relative humidity. Temperature and windspeed are independent parameters. Relative humidity will change with changes in temperature, but the temperature will not change as a function of the other parameters. The only time when humidity can change the temperature is if evaporation is taking place. For example, on a hot very dry day, the actual temperature of your skin can drop due to the evaporation of sweat. This is part of your body's natural cooling system. The ambient air temperature is not changing, but the surface temperature of your skin is. technically, the ambient air temperature can change, as the evaporation is an endothermic process. but using a human as an evaporative cooler is not going to cool any significant amount of space. That is correct. But air conditioning systems also depend on evaporation to cool entire buildings. Refrigeration systems depend on a refrigerant evaporating inside a coil of tubing. This causes the tubing to get very cold and when air is blown over the tubing, it cools the air. Some building cooling systems in very dry climates use water as the refrigerant. |
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Post by the light works on Jul 22, 2016 14:29:59 GMT
technically, the ambient air temperature can change, as the evaporation is an endothermic process. but using a human as an evaporative cooler is not going to cool any significant amount of space. That is correct. But air conditioning systems also depend on evaporation to cool entire buildings. Refrigeration systems depend on a refrigerant evaporating inside a coil of tubing. This causes the tubing to get very cold and when air is blown over the tubing, it cools the air. Some building cooling systems in very dry climates use water as the refrigerant. I wasn't saying swamp coolers aren't a thing. I was saying a human body is a very inefficient one. |
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Post by GTCGreg on Jul 22, 2016 16:28:57 GMT
That is correct. But air conditioning systems also depend on evaporation to cool entire buildings. Refrigeration systems depend on a refrigerant evaporating inside a coil of tubing. This causes the tubing to get very cold and when air is blown over the tubing, it cools the air. Some building cooling systems in very dry climates use water as the refrigerant. I wasn't saying swamp coolers aren't a thing. I was saying a human body is a very inefficient one. For cooling air, yes. But for cooling the body, it can be very effective provide the humidity is low enough. |
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Post by the light works on Jul 23, 2016 2:18:05 GMT
I wasn't saying swamp coolers aren't a thing. I was saying a human body is a very inefficient one. For cooling air, yes. But for cooling the body, it can be very effective provide the humidity is low enough. and the water tank don't run dry. |
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Post by silverdragon on Jul 23, 2016 9:27:44 GMT
Humidity is a "bad thing" around molten metal.
I know smelters who demand a dry atmosphere.
For good reason.....
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Post by GTCGreg on Jul 23, 2016 13:26:38 GMT
Humidity is a bad thing around any metal, Molten or not. There are company that make big dollars selling corrosion prevention coatings.
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