8 Science-Backed Tips to Keep Your Feet From Burning on Hot Sand

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With temperatures hitting record highs this summer, beaches—and their promise of cool ocean dips—beckon. But to reach the waves, it's likely you'll first have to cross an expanse of foot-scalding sand. Sand is made up of decomposed rock—quartz, mostly, but also calcite, feldspar, gypsum, or basalt, sometimes with a smattering of shell, coral, or fish poop tossed in—and according to Paul Jarvis, a geologist and volcanologist at the University of Geneva, it receives solar energy via the process of radiation. The composition of sand causes it to heat up as the day progresses and to retain that heat, reaching temperatures as high as 140°F—sufficient to inflict third-degree burns. Here are tips for protecting your soles from this painful outcome.

1. WEAR THE RIGHT KIND OF SHOES.

This seems obvious, but the level of protection you get depends on the kind of shoe you're wearing. Materials such as plastic and rubber (what many soles are made of), foam resin (the stuff of Crocs), and the neoprene base of the Sand Socks that many beach volleyball players swear by provide a barrier between skin and sand. This helps cut down on conduction—the transfer of heat from the warmer surface of the sandy beach to the cooler surfaces of your feet. As a result, your feet are protected (at least temporarily) from blistering. And though they're likely the first shoes you picture when you think of the beach, flip-flops and other open shoes should be avoided on especially scorching days, because they let the hot sand in.

2. MAKE A PATH USING A COUPLE OF BEACH TOWELS.

Forgot your shoes in the car? You can protect your feet by rolling out a couple of towels to step on, repeating the process until you reach your coveted beach spot. The cotton of your towel is better at quelling heat transfer to your feet than the rubber soles of your shoes are due to what scientists call a lower thermal conductivity—“the measure of how fast heat can be conducted through the material,” Jarvis tells Mental Floss. However, your towel is also thinner than your shoe bottoms, and heat conducts faster through thin objects. In other words, you’ll have to hurry if you want to keep your feet cool.

3. RUN FAST …

The less time the soles of your feet spend touching the sand, the less time there is for conduction. But sprinting is probably a technique best reserved for covering short distances or for morning beach visits, before the sand has had a chance to soak up the solar rays for several hours and achieve maximum temperature. Because no matter how fast you run, conduction is still happening, and after some strides, your feet will eventually begin to feel the burn.

4. … OR BURROW YOUR FEET.

If you're loaded down with a cooler and tote bags, try a technique favored by professional beach volleyball players: Burrowing your tootsies as you walk, which puts your feet in contact with the much cooler sand beneath the surface. Because there are large gaps between grains of sand, it's “unable to efficiently transmit heat … through the sand bed to [its] deeper levels,” Jarvis says. So dig in a few inches. This way of “walking” is actually more of a slow shuffle, but it'll get you to your destination sans burns.

5. WET THE SAND …

It takes five times as much solar energy to heat water 1°C (33.8°F) as it does to heat sand by the same amount (what's technically known as heat capacity). So “adding just a small amount of water to the sand can dramatically increase the amount of heat the sand surface needs to receive before it gets hot,” Jarvis says. You can replicate the effect by toting a bucket of water and tossing its contents under your feet little by little as you go. While not the easiest method, it could be a solution for when you're already near the water and have to, say, run to the restroom or buy a snack. Just grab one of the kids' sand-castle buckets. Wet sand is also a lot less arduous to walk and run on than dry sand.

6. … OR YOUR FEET.

American pro beach volleyball player Sara Hughes has a go-to sand strategy: “To cool down, I personally like to put water on my feet,” she told USA Volleyball's blog. According to Jarvis, because water has a higher heat capacity than human skin, having wet—and therefore colder—feet means "you can be exposed to the beach for longer before your skin reaches a temperature at which it will burn.” Obviously, this is a highly temporary solution, since your feet will quickly dry. So bring the bucket for this tactic too: You might have to dip your feet into the water several times before reaching your ultimate destination.

7. FOLLOW THE SHADE.

Since it doesn’t take a lot of energy to change the temperature of sand, areas in shadow will feel noticeably cooler to the touch. It's easier to find those spots early in the morning or at the onset of evening, when the Sun is at an angle to the beach; the rest of the day, keep an eye out for shadowed spots made by the lifeguard chair, beach umbrellas, or palm trees to give your feet relief.

8. FIND A LIGHT-COLORED BEACH.

Should you opt to go shoe-less, choose your sand wisely. The heat capacity of the sand on any beach you visit is dependent on what minerals it’s comprised of—a challenge to know unless you do your own scientific studies, beach by beach. However, a general rule of thumb is that hotter beaches come with darker sands—and the opposite is also true. “Light-colored sand reflects, as opposed to absorbs, a significant proportion of the Sun’s radiation,” Jarvis says. “Dark sand, such as that originating from volcanic rocks [like basalt], is much more heat absorbent, meaning it will heat up quicker and therefore, potentially become much hotter.”

Why Is Pee Yellow?

Chloe Effron
Chloe Effron

WHY? is our attempt to answer all the questions every little kid asks. Do you have a question? Send it to why@mentalfloss.com.

Your body is kind of like a house. You bring things into your body by eating, drinking, and breathing. But just like the things we bring home to real houses, we don’t need every part of what we take in. So there are leftovers, or garbage. And if you let garbage sit around in your house or your body for too long, it gets gross and can make you sick. Your body takes out the garbage by peeing and pooping. These two things are part of your body’s excretory system (ECKS-krih-tore-eee SISS-tem), which is just a fancy way of saying “trash removal.” If your body is healthy, when you look in the toilet you should see brown poop and yellow pee.

Clear, light yellow pee is a sign that your excretory system and the rest of your body are working right. If your pee, or urine (YER-inn), is not see-through, that might mean you are sick. Dark yellow urine usually means that you aren’t drinking enough water. On the other hand, really pale or colorless pee can mean you might be drinking too much water! 

Your blood is filtered through two small organs called kidneys (KID-knees). Remember the garbage we talked about earlier? The chemicals called toxins (TOCK-sins) are like garbage in your blood. Your kidneys act like a net, catching the toxins and other leftovers and turning them into pee.

One part of your blood is called hemoglobin (HEE-moh-gloh-bin). This is what makes your blood red. Hemoglobin goes through a lot of changes as it passes through your body. When it reaches your kidneys, it turns yellow thanks to a chemical called urobilin (yer-ah-BY-lin). Urobilin is kind of like food coloring. The more water you add, the lighter it will be. That's why, if you see dark yellow pee in the toilet, it's time to ask your mom or dad for a cup of water. 

To learn more about pee, check out this article from Kids Health. 

Why Do Grown-Ups Have Wrinkles?

Chloe Effron / iStock
Chloe Effron / iStock

WHY? is our attempt to answer all the questions every little kid asks. Do you have a question? Send it to why@mentalfloss.com.

Our skin is supposed to stretch. We do it every day when we squint in the sunlight, make a silly face, smile, laugh, pout, or furrow our eyebrows. Each time our skin stretches, tiny lines and grooves start to form below the surface. Over time, the outside skin gets thinner and dryer, and it falls deeper into those little grooves. As we get older, we also lose some of the stuff in our skin that helps it to stretch and then return to its normal place. 

First, let’s talk about our three layers of skin. The outside part is called the epidermis (eh-pih-DER-mis). That’s the part you can see. Under that is our dermis, where we have stretchy fibers called elastin that let our skin stretch and then go back to its normal position, just like an elastic hair band. The dermis layer also has collagen (KAHL-uh-jen), a protein that helps it stay sturdy and grow new skin cells. Under the dermis is the deep subcutaneous (sub-kyoo-TAY-nee-us) layer, which stores fat. As we get older, we start to lose collagen, elastin, fat, and oils made by our skin that keep it moisturized, or less dry.

There are lots of reasons. Our bodies make less of these things as we age, so our skin gets thinner, drier, and less stretchy. The Sun’s ultraviolet (UV) light also breaks down collagen and elastin fibers. This causes more lines and wrinkles. But wrinkles are just a part of life. One day, you’ll have them too. Take good care of your skin by wearing sunscreen and drinking plenty of water to help your skin stay moisturized.

For further reading, visit Kids Health.


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