# Different materials have different temperatures?

Why do two materials, under the same weather, have different temperatures?

I have a small clue about it. For example, iron and wood supposed under the sun's radiation, and if we touch both of them, we'll notice a remarkable difference in temperatures just on the surface, or even by a near area, and that's a fact about the material itself if it reflects radiations totally (as the iron) or just a part of it (as the wood) .

That just leads to another question, if that was true then why in a cold area we found totally reversed results, because if we put the same materials in a cold area, and as the iron is the one who's going to reflect energy more than the wood, we found out that iron is actually colder than the wood?

That problem is really making me nervous and I keep asking people but none had the the convincing answer.

• What were those "unconvincing" answers "people" gave to you? May 26, 2015 at 2:20
• May 26, 2015 at 2:23

When you touch something, you don't feel how hot/cold the thing is; you feel how hot/cold it makes your hand. Metal conducts heat more easily than wood. So if wood and metal are hot, the heat will flow more easily from the metal to your hand. If wood and metal are cold, the heat will flow more easily from your hand to the metal.

• Thanks that was much more convincing one. We shouldn't forget material's own properties such as color ,surface etc .. May 25, 2015 at 23:35
• nicely put jimmy, I always remember that cold part question from way back
– user81619
May 25, 2015 at 23:37

The answer depends on whether the materials are in the sunlight (including on a cloudy day), in which case the wood is actually cooler than metal. In addition, when they are the same temperature the metal will feel hotter on a hot day and cooler on a cold day because of the rate of heat/cold transferred from the metal to the body. To prove the first statement is simple: place a thermometer on wood and one on metal that are in the shade and they will register the same temperature. Once in the materials are in the sun, keeping the thermometers out of direct sunlight, the metal will register a hotter temperature than the wood, the largest temperature difference being when the sun is strongest even though they are the materials are the same color. Thus, one in a white wood building on a hot day will be cooler than one in a metal building the same color once both reach equilibrium.

The two materials possess different thermal conductivities. The metal appears to have a higher temperature because the heat escapes it into your fingers quicker than the wood. http://en.wikipedia.org/wiki/Thermal_conductivity

italicized part edited to not confuse future readers.

• @Acid Jazz, I am pretty sure that they are not at the same temperature given the same conditions. I'll withdraw my answer if proven otherwise. May 25, 2015 at 23:22
• actually now that I think about it.. the case with the sun is not of conduction but of radiation. Is thermal conductivity still applicable to the sun's radiation warming the metal and wood? May 25, 2015 at 23:28
• @Obliv Yes, it is. May 25, 2015 at 23:28
• Well .. thats what i said actually, the metal would feel warmer. It's due to its conductivity .. do you mean the metal has the ability to pass temperature "grad" better than the wood ? May 25, 2015 at 23:30
• Yes. Metal has 'mobile' electrons that allow its thermal conductivity to be much greater than wood which is considered an insulator. The structure of wood leaves air pockets in between the fibers of the solid. Air is a good insulator and thus lowers the thermal conductivity of the material. May 25, 2015 at 23:35

I don't think it is due to thermal conductivity of material. Actually, thermal conductivity is characterised for the rate of heat transfer across (inside) a material. When you put your fingers on the surface of a material, thermal conductivity of the material no longer affects your feeling, but only the thermal conductivity of YOUR SKIN.

The main reason for your different feelings is the difference in Heat capacity. Iron has smaller value of heat capacity than wood. So, in the same time interval, with the same heat energy transfered (sun radiation), the increase in temperature of iron is larger than of wood. So, the temperature of iron is larger than of wood. As a result, you get different feelings.