We all have this experience. In the winter, when we touch the iron and the wood with our hands, we will feel that the iron items are much colder than the wooden items. Why is this feeling? You might say: because their temperatures are different!
Is that true? Let’s use a thermometer to measure the temperature of iron and wooden items. The readings of the thermometer tell us that the temperatures are exactly the same.
It turned out that this is because iron heat transfer is much faster than wood. The heat transfer capability of the object is related to the thermal conductivity of the material. The material with high thermal conductivity transfers heat quickly, and the material with low thermal conductivity has slow heat transfer. Iron has a higher thermal conductivity than wood, which means that iron transfers heat much faster than wood.
In winter, when we touch the iron items, the heat of our hands is quickly transferred to the iron items because of the strong heat transfer capacity of the iron. When the wooden items are touched, the heat transfer ability of the wood is poor. The heat in your hand passed slowly. So, we will feel that iron is much colder than wood.
It turned out that we felt that iron was much colder than wood because the heat from the hands was transferred to the iron faster, not because the temperature of iron and wood was different.
It is precisely because of the difference in thermal conductivity that the summer situation is just the opposite of winter. When the ambient temperature is higher than the human body temperature, because the iron heat transfer is fast, the temperature of the iron article is quickly transmitted to the hand, so it will feel in the summer. Iron is much hotter than wood.