Let us imagine you have a stainless steel cup of ice cream in the fridge. You opened the fridge; the air inside was cold. You stretched out your hand to pick your favourite ice cream and got a jolt.
"Ouch!"
It was numbingly cold!
By Damianosullivan (Own work) [CC BY-SA 3.0 Source, via Wikimedia Commons
But the fridge and the air inside the refrigerator is at the same temperature. Why did the cup appear colder than the air?
This same experience repeats itself in another instance. An air-conditioned room at 15 degree Celsius (60 °F) feels pleasant. But if you enter into the shower and a 15°C (60 °F) water suddenly splashes on you, you'd probably jump out of the bathroom due to how cold it was.
But a thermometer indicates the two materials are at the same temperature.
The questions are these, how does the metal appear colder than air at the same temperature?
Why did the water appear colder than air when they are both the same temperature?
The old physics is here to the rescue. Again.
The perception of different temperature is dependent on the thermal conductivity of different materials. Or more specifically heat transfer.
Thermal conductivity merely is the capability of a material to conduct heat.
The heat transfer occurs at a higher rate for materials that have a high conductivity, and at a lower rate for material with low thermal conductivity.
Take a look at the different material and its thermal conductivity in the table below.
| Material (@25 °C or 77°F) | Thermal Conductivity in Watts/meter-kelvin, W/(m.K) |
|---|---|
| Acrylic | 0.2 |
| Air | 0.024 |
| Aluminium | 205 |
| Copper | 401 |
| Carbon Steel | 54 |
| Concrete | 1.050 |
| Glass | 1.050 |
| Gold | 310 |
| Nickel | 91 |
| Paper | 0.050 |
| PTFE(Teflon) | 0.250 |
| PVC | 0.190 |
| Silica aerogel | 0.02 |
| Silver | 429 |
| Steel, Carbon 1% | 43 |
| Stainless steel | 16 |
| Water | 0.606 |
| Wood | 0.130 |
The important aspect is the style that heat is absorbed or escapes by your body.
If the temperature of the medium(mostly air, water, etc.) that surrounds a body is lower than your body's temperature, your body will give off heat. Or behave in the reverse direction (absorb heat) if otherwise.
Your body's heat transfer or heat loss is fastest on materials that are good conductors. The amount of heat loss is also determined by the thermal conductivity of the material, the higher it is, the more the heat lost when you touch it.
For instance, a stainless steel spoon and a wooden spoon are both inside the same place at room temperature. The stainless steel spoon will appear colder to touch.
Your hand is warmer than the room temperature, both the metal and wooden spoon conducts heat away from your hand.
The metal spoon will conduct the heat away from your hand faster than the wooden spoon would. And give you the impression that steel spoon is colder than the wooden one.
The same thing happens when you leave both spoons in a piping hot soup. The steel spoon will absorb heat more than the wooden spoon and appear warmer to touch.
The water in the bathroom absorbs more heat away from your body faster than the air. Hence the feeling of it being colder than the air.
References
* Thermal Conductivity
* Thermal Conductivity of Different Materials
* Why does cold metal seem colder than cold air?
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Thank you.
Thanks for the post, very educative and interesting. But the amazing thing about the early morning cold especially during the harmattan is that the moment the water touches your body, you will not feel the cold again and you could barely stay on without putting on any clothing. I remembered my mum used to tell me then that the best way to deal with cold or harmattan is to bath with cold water.Any explanation for this?
I think it's more biological than any other thing. It is just the body adjusting to the new temperature, much the same way most people living in the tropics can withstand higher temperatures while their contemporaries in the temperate regions can withstand more lower temperatures.
@greenrun is a research genius. The way you think ehn, issorai.
We'll get thee too. I apparently witness this most times but I've never thought of the physics. Thanks for helping us out, our "Physics Teacher" ..
Keep steeming boss
We recently lost a genius, his name was Stephen Hawking.
Thanks for the compliment.
Yeah, definitely. He lives on in our hearts.
You're welcomed.
This reminds me of my days in school
The cold water bath in the cold mornings? I can totally relate, I dread the mornings of such days especially during the harmattan :)
Bathing during harmattan requires special skills. Lol
My only skill is to spend as little time as possible in the bathroom. That way you'd survive for another day of cold water "torture" :)
Lol
Interesting fact. Had never thought about it but always felt this. This is why my car seats were much colder when they were of rubber but not cold anymore after the cushioned covers.
True, the thermal conductivity of the material affects how you perceive temperature from it.
This reminds me of thermodynamics class, testing of the different thermal conductivities of materials, and definately school, where skipping afew days during the cold season wasn't that baaaad.
Had missed your posts, SteemOn!
fun. Though, I'd tell younger ones not to try it :)Thank you @cmbugua, skipping school was
This is like good schooling for me have never really thought of thermal conductivity in this perspective.
Glad to help in this regard. Thanks.
I can relate...
I mean no wonder......
The next time i reach out for my ice cream, I'll remember why the cointainer is cold, and as for the shower, especially during hammattan jeeeeez.....
Oh yes! Thank you.
I practice this simple physics too whenever I want to pick q hot spoon left inside the food. I touch it tightly for a brief moment and drop it immediately. I believe thru conductivity, a good amount of heat energy is lost. Picking it up thereafter is always easier.
That's a perspective I'd like to check up more on. Thank you.
What an insightful post.
I sometimes would wish i could skip the morning bath during the cold season but my mum will killlll me!
The physics behind these things are simply awesome.
Thanks for sharing
It is something that is relatable. No one wants a cold bath on a cold day.
I can't forget those days in secondary school during harmattan. I will always start the bath from my feet and take it up little by little. It's fascinating to learn the physics behind it. Kudos @greenrun.
Thank you.
Very good concept and explained Welly. Genius #greenrun
wow you are opening new dimensions in learning each day its awesome D:
Feels good to be here again. Actually, I have never asked my self this question. But i think the water during harmattan has absorbed a cold temperature from the environment and should be at the same temperature with the air. But our body like you say does something called amazing by adjusting to the temperature of the water very fast than the air. Does this mean water looses its temperature faster than the air?
Interesting! It's amazing how you know all this simple yet incredible things