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Why Does Humid Weather Make Hair Frizzy?

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People with long hair know that even the most meticulously primped 'do is at the mercy of the weather. When the air is humid, hair can start to crimp, curl, or frizz the moment you step outside. Don't just curse the weather every time your hair takes on a mind of its own: the chemical makeup of your locks is also to blame.

A strand of hair is composed of bundles of a fibrous protein called keratin, and the shape and structure of your hair is determined by how these proteins bind together. Keratin molecules contain high amounts of the amino acid cysteine, which in turn contains sulfur atoms. When two keratin chains are nearby, the sulfur atoms from the neighboring molecules can react to form a strong disulfide bond. These bonds lock keratin molecules together and maintain their composition whether your hair is wet or dry. You have them to thank for much of your hair's durability and strength.

Hydrogen bonds are much more numerous in hair, and a lot more fickle. They form when a positively charged hydrogen molecule gets caught between two electronegative atoms in a strand of hair. Unlike disulfide bonds, the hydrogen bonds that form between these atoms are easily dissolved when wet. They break down and form anew each time you take a shower and dry your hair. They're also affected by the humidity in the air.

Instead of breaking down the hydrogen bonds in hair, the right level of humidity produces these bonds in greater numbers. More hydrogen molecules provide more opportunities for hydrogen bonds to form with keratin proteins. As more bonds form, proteins start to double back on themselves, resulting in curly or frizzy hair.

These effects are amplified in hair that's especially dry. Dry hair tends to soak up moisture in the air like a sponge, breaking the strand's outer shaft and making hair look frizzy. This is why hair that's been damaged by heat, chemical coloring, or an overuse of products is often more vulnerable to humid weather.

One way to fight the frizz is by moisturizing your hair before leaving the house. Conditioners, natural serums, and all-around gentler treatment can help cut down on dryness. If that doesn't work, we suggest avoiding tropical climates whenever you can.

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Why Does the Sky Look Green Before a Tornado?
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A common bit of folklore from tornado-prone parts of the U.S. says that when the skies start taking on an emerald hue, it's time to run inside. But why do tornadoes tend to spawn green skies in the first place? As SciShow's Michael Aranda explains, the answer has to do with the way water droplets reflect the colors of the light spectrum.

During the day, the sky is usually blue because the shorter, bluer end of the light spectrum bounces off air molecules better than than redder, longer-wavelength light. Conditions change during the sunset (and sunrise), when sunlight has to travel through more air, and when storms are forming, which means there are more water droplets around.

Tornadoes forming later in the day, around sunset, do a great job of reflecting the green part of the light spectrum that's usually hidden in a sunset because of the water droplets in the clouds, which bounce green light into our eyes. But that doesn't necessarily mean a twister is coming—it could just mean a lot of rain is in the forecast. Either way, heading inside is probably a good idea.

For the full details on how water and light conspire to turn the sky green before a storm, check out the SciShow video below.

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New Contest Will Give Kids the Chance to Become Weather Channel Meteorologists for a Day
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Not every kid dreams of being an on-air meteorologist, but for young ‘uns obsessed with storm forecasts and local weather reports, a new contest presents a unique opportunity to live out their dreams. The Mini Meteorologist Contest, sponsored by Lands’ End, will give four kids a chance to present a weather report on The Weather Channel this summer.

The nationwide contest is open to future meteorologists in the U.S. and Canada ages 6 to 16. To enter, they just have to write an essay between 50 and 500 words long on why they love learning about science and weather and why they’d like to be a meteorologist for a day. Four winners will receive a trip for them and their parents to The Weather Channel’s headquarters in Atlanta. They’ll have the opportunity to report the weather for the show on July 12, which happens to be National Summer Learning Day.

The essays will be judged based in equal parts on creativity, grammar, and the entrant’s love of meteorology. The only rules for the essays are that they can’t mention any products or brands other than Lands’ End or The Weather Channel (so no essays about how L.L. Bean inspired your love of cloud formations, kids) and has to be the child’s original work. Kids who are chosen as semi-finalists will have their on-air presentation skills judged in a Skype interview.

Should they win, they’ll get an inclusive trip to Atlanta with media training, a tour of The Weather Channel headquarters, and a $500 Lands’ End gift card to get just the right weather-reporting wardrobe.

The deadline for entering is May 21. Essays can be submitted here.

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