Placeholder Image

Subtitles section Play video

  • Thanks to Raycon for supporting this episode of SciShow.

  • They've got some early Black Friday and Cyber Monday deals that are available today for a limited time only, so click the link in the description to check out Raycon's wireless earbuds.

  • [INTRO ♪]

  • You know what they say: It's not the heat, it's the humidity.

  • And that's extra true if your hair is the frizzy type.

  • The higher the humidity, the more prone some of us are to a frizz-tastrophe, and it all has to do with how water interacts with the proteins in our hair.

  • The really weird thing, though, is what hair has been able to teach us about atmospheric water.

  • Frizz is what you get when individual strands of hair change shape and stop matching the neighboring strands.

  • This can mean getting curly, wavy, or otherwise infuriatingly irregular.

  • Frizzing has to do with hair's composition.

  • Hair is made up of a long, fibrous protein called keratin, bundled layer upon layer in an elaborate structure.

  • The keratin molecules stay together through a combination of strong and weak chemical interactions.

  • The real beefy chemical bonds are called disulfide bonds, in which sulfur atoms from neighboring protein strands join together in a pretty tight hold.

  • And the weaker interactions are what's known as hydrogen bonds.

  • Hydrogen bonds aren't true chemical bonds.

  • Rather, they're a weak attraction between a slight positive charge and a slight negative charge.

  • For hair, the hydrogen bonding happens between keratin molecules and water molecules.

  • When a water molecule bonds to two different keratins, it can help hold them togetherto an extent, but that hold can be easily broken or changed.

  • And when more water enters the picture, it can change how keratin sticks together.

  • Getting your hair wet can break previous hydrogen bonds and form new ones, resulting in a new shape to your hair.

  • And when your hair dries in a certain shape, it tends to staywhich is why going to bed with your hair wet is asking for epic bedhead.

  • When there's lots of water in the air in the form of high humidity, the changes to our keratin molecules are more unpredictable.

  • Frizz occurs when water is absorbed into dry hair in different areas at different rates.

  • Some strands of hair may absorb water into the center, while others may absorb less, or none at all, causing differences in swelling that affect hair shape.

  • Alternatively, the higher moisture may cause some strands to form so many hydrogen bonds around the outer layers that the hair folds back on itself, forming curls.

  • And the water absorption is pretty random.

  • No two adjacent hairs respond to airborne moisture the same way, resulting in the frizzy mess that we find so frustrating.

  • They all get bent out of shape differently.

  • But the amount of water a hair absorbs is ultimately still proportionate to the relative humidity.

  • Like, it's predictable enough to be useful for making measurements.

  • Measuring humidity was a goal of scientists back in the day who wanted to know more about what caused rain, and how predictable various weather phenomena could be.

  • Enter the hygrometer, a device for measuring relative humidity.

  • One of the first hygrometers was made in 1783 by Horace Bénédict de Saussure.

  • And his worked using human hair.

  • This may seem weird and kinda gross, but it's both effective and something you can try for yourself!

  • Because dry hair will absorb atmospheric moisture, you can reliably observe a long strand of hair to change shape as humidity changes.

  • All you have to do is fix one end of a clean, de-oiled strand of hair in place and hang a weight from the other end to keep it stretched.

  • Then you can observe the length of the hair changing as humidity increases or decreases.

  • The proteins coil and uncoil as hydrogen bonds form and break, all as a function of how much water is in the air.

  • So the resulting variation in the strand's length is proportionate to the humidity in the air.

  • You can even calibrate relative humidity by using a hair dryer to simulate 0% and a wet rag for 100%, allowing you to get a sense of how far between those two extremes the air is on any given day.

  • So while it might be a seasonal annoyance, at least frizz has some practical applications!

  • Thanks for watching this episode of SciShow, which was sponsored by Raycon.

  • Raycon offers wireless earphones in a range of fun colors and patterns.

  • They're super sleek, with no dangly wires or stems getting in the way, and more importantly, they're super comfortable.

  • And their latest model, the E25, is their best one yet, with 6 hours of playtime, seamless Bluetooth pairing, more bass, and a more compact design that gives you a nice, noise-isolating fit!

  • If you're interested, you can go to buyraycon.com/scishow or click the link in the description!

  • [OUTRO ♪]

Thanks to Raycon for supporting this episode of SciShow.

Subtitles and vocabulary

Click the word to look it up Click the word to find further inforamtion about it