To rephrase, if a rock sits outside in 10F weather with -10F windchill, is the rock’s surface temperature 10F or -10F?
In: 4775
To make a long story short, if the temperature of the rock is already at 10 F, then the windchill has absolutely no impact on it. It doesn’t matter if the windchill is 0F or -70F, it’s all the same.
Where things change, however, is when that rock starts out significantly hotter (or colder!) than the ambient temperature. If it starts out at, say, 20 F, then a -10 F windchill will cool it down significantly faster than if there is no windchill – but in both cases, it will eventually stabilize to 10 F. Interestingly, if the rock starts out at -20 F, then it will warm up to the 10 F ambient temperature *faster* if there is a -10 F windchill than if there is no wind.
Here’s the important thing to consider: heat is transferred between the rock and the air through conduction – it’s just like putting a pot of water on a hotplate. The key thing to keep in mind is that heat transfers more quickly when there is a greater difference in the temperature of the two items – in this case, the rock and the air. If the air sits stagnant, the air around the rock will warm up, slowing the rate of heat loss from the rock. If air is constantly blown across the rock, there is always a fresh supply if cold air. If the rock is colder than the air, the reverse happens. This is why heatsinks in electronics are often equipped with fans.
The reason that a wind chill makes it feel that much colder is that the internal temperature of humans is almost always significantly higher than the ambient temperature.
Latest Answers