Exploring humidity’s increasingly limited impacts as temperatures drop
We are more than familiar with humidity here in mid-Missouri.
The word conjures up memories of hot summer days and uncomfortable feelings, but probably not cold days, and there’s a reason why. However, some say cold days feel colder with humidity than they do without. Is that true? There is some science behind it.
The term humid denotes air rich in moisture. This impact is less noticeable in winter than it is in summer, but it can slow down your body’s warming process.
This is because of something called specific heat capacity. This is basically the amount of energy you need to increase something’s temperature.
Water has a higher specific heat capacity than the air around us. When you put more water in the air, it takes more energy to warm it. This is why air over water warms and cools slower than that over land. More energy is needed to warm moist air.
For a demonstration, I have a lighter, and two balloons. One balloon has air, and when held over a flame it pops! The lighter’s energy is heating the balloon quickly in this example. With a water filled balloon, you may be surprised it takes longer to pop, but don’t be! The water keeps the balloon cool enough to not pop by slowing the warming process.
In winter, our bodies keep us warm by radiating heat to a thin layer of air around us. In a humid environment, the body heat process can be slowed, as it takes more body heat to warm air with added moisture.
The problem with all of this is that cold air cannot hold as much moisture as warm air, and so the colder the air gets, the less impact moisture has. But you may feel it still, and you're more likely to feel this impact on on a cool rainy day, than a cold and snowy one.
