Eli5: why do lips get chapped in cold weather compared to hot? Doesn’t the hot air absorb the moisture more?


Eli5: why do lips get chapped in cold weather compared to hot? Doesn’t the hot air absorb the moisture more?

In: Biology

Hot air does make moisture move more, but that also includes nearby water sources, making the air more humid.

The higher water content of the warm air doesn’t suck from your lips as much as the very dry cold air.

Plus, when it’s warmer, you’re sweating more, applying moisture more directly.

Do you live somewhere with high humidity in the summer? I don’t experience much of a difference in this between summer and winter. And if anything summer is worse. Spring and fall are better though. In cold weather when you encounter a forced air heating system such as your car heater or home central heating the air coming out of these will have extremely low relative humidity because even if the air had high humidity going in once heated the air holds s lot more water so the repetitive humidity goes way down. In the summer where I live exterior humidity is regularly in the low teens with high heat, intense sun, and possibly wind. Those will all be hard on exposed skin causing chapped lips and nosebleeds in those who are vulnerable. While inside the humidity will be higher for the opposite effect as mentioned with heaters but AC does actually pull some water out of the air.

Air is like a sponge when it comes to holding water. Hot air is like a sponge that isn’t being squeezed it can hold a lot of water, and if it’s dry it will steal water from it’s surroundings. Cold air is like a sponge that is being squeezed it can’t hold a lot of water. Your heater takes the dry cold air from outside and heats it up (releasing grip on the sponge) this blows dry hot air at your face and takes all of the water from your body.

Nah, you dehydrate quicker in the cold. It’s usually drier than the heat, deserts being the exception of course, and also, the base point for “cold” is much farther from your body’s core and surface temperatures than the base point for “hot”, so your body is gonna use up a lot f water maintaining homeostasis. Think about it. What’s “hot”? 90, 100 F? Your core temp is 96, your surface temp is, maybe 80 to 85 F. Meanwhile, cold is 50 or so, even 60, the difference between the latter temperatures and your body’s temp is much larger than the difference between the former and your body’s temp. So you expend more resources maintaining.

Also, chapped lips are not solely a function of dehydration. Wind damage, and cell damage due to the actual cold factor in as well. Not to mention you end up licking them in the cold, effectively creating an evaporating layer that takes some moisture with it each time it evaporates.

Everybody who moves to Arizona (and other desert climates) ends up with chapped lips until your body gets used to it. Most people start off using chapstick, and you can do that indefinitely, but if you stop, your lips will be really chapped for about a week, and then they’ll just adapt and you won’t have to use chapstick any more.

A lot of people end up with bloody noses as well, due to the lack of humidity. Thankfully you adapt.