“Why do we shiver when we feel cold?” – Syeda, age 10, from Karachi

What a cool question, Syeda!

Our bodies like to be nice and warm, usually around 37°C. This allows our internal functions to work at their best. But our bodies are constantly losing heat to the outside air.

When it’s cold outside, or if we jump into a cold swimming pool, or even if the air-conditioning is a bit strong, our body temperature can lower, sometimes to levels that are uncomfortable.

If our body temperature drops too low, our heart, nervous system and other organs are not able to work normally. If it falls to extremely low temperatures, called hypothermia, this can cause some organs to completely fail.

Luckily, our bodies have their own internal heaters to protect us against small changes in temperature. This is mostly thanks to the actions of our muscles, through a process called thermoregulation. It’s this process that leads our bodies to shiver when we’re chilly.

Muscles are our bodies’ personal heaters

When our muscles twitch, they generate movement. This is called “muscle contraction”, and can involve the muscles tightening and shortening.

Muscle contractions help us walk around, smile, lift heavy objects and high-five each other.

Moving our muscles also generates a bit of heat. With many muscles moving most of the time, this helps our bodies stay nice and warm.

The more our muscles move, the more heat they generate. This is why you might feel hot and bothered after running around or playing sports.

On the other hand, when we stop moving our muscles, we start to cool down. This is one of the reasons we cover up with bedsheets at night.

What about the shiver?

Shivering is the rapid contractions of our muscles over and over. This doesn’t generate any significant movement, but instead releases heat that helps to warm us up.

Most of the time we don’t have control over when our brain tells our muscles to shiver. We have special sensors throughout our body that pick up when our system is cold, and our brain then responds by telling the muscles to start shivering.

And we aren’t the only ones who shiver! All mammals have the ability to shiver, so your pet cat or dog might shiver when they’re cold too. Even birds shiver.

When it’s a chilly day outside, you might also notice you get goosebumps. Goosebumps happen when tiny muscles connected to the hair follicles (from which our hair grows) tighten. This causes the little hairs on our arms to stand up, helping to trap in warm air and slow down body heat loss to the outside.

How can you ‘chill out’ your shiver?

Thermoregulation is key to maintaining a nice, consistent body temperature, which keeps our internal organs happy.

While shivering can help us warm up, it’s best to make sure you wear the right clothes if you’re going to be out in the cold.

Hello, Curious Kids! Do you have a question you’d like an expert to answer? Ask an adult to send your question to curiouskids@theconversation.edu.au

Charlotte Phelps, Senior Teaching Fellow, Medical Program, Bond University and Christian Moro, Associate Professor of Science & Medicine, Bond University

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Curious Kids is a series for children of all ages. If you have a question you’d like an expert to answer, send it to curiouskidsus@theconversation.com.

How is snow made? – Tenley, age 7, Rockford, Michigan

The thought of snow can conjure up images of powdery slopes, days out of school or hours of shoveling. For millions of people, it’s an inevitable part of life – but you may rarely stop to think about what made the snow.

As a professor of atmospheric and planetary sciences, I’ve studied how ice crystals floating in the sky become the snow that coats the ground.

It all starts in the clouds.

Clouds form when air near the Earth’s surface rises. This happens when sunlight warms the ground and the air closest to it, just like the Sun can warm your face on a cold winter day.

As the slightly warmer air rises, it cools – and the water vapor in that rising air condenses to form liquid water or water ice. From that, a cloud is born.

Endless pathways

When temperatures are well below freezing on the ground, the clouds are primarily made of water in the form of ice. Under 32 degrees Fahrenheit – that’s zero degrees Celsius – the frozen water molecules arrange themselves into a hexagonal, or six-sided, crystalline shape. As ice crystals grow and clump together, they become too heavy to stay aloft. With the help of gravity, they begin to fall back down through and eventually out of the cloud.

What these ice crystals look like once they reach land depends on the temperature and humidity of the atmosphere. As the humidity – or the amount of water vapor in the cloud – increases, some of the ice crystals will grow intricate arms at their six corners. That branching process creates what we think of as the characteristic shapes of snowflakes.

No two ice crystals take the same path through a cloud. Instead, every ice crystal experiences different temperatures and humidities as it travels through the cloud, whether going up or down. The ever-changing conditions, combined with the infinite number of paths the crystals could take, result in a unique growth history and crystalline shape for each and every snowflake. This is why you’ve likely heard the saying, “No two snowflakes are exactly alike.”

Many times, these differences are visible to the naked eye; sometimes a microscope is required to tell them apart. Either way, scientists who study clouds and snow can examine a snowflake and ultimately understand the path it took through the cloud to land on your hand.

Liquid water as glue

When snow falls from the sky, you don’t usually see individual ice crystals, but rather clumps of crystals stuck together. One way ice crystals aggregate is through what’s called mechanical interlocking. When ice crystals bump into each other, crystals with intricate branches and arms intertwine and stick to others.

This mechanism is the main sticking process in cooler, drier conditions – what people call a “dry snow.” The result is a snow perfect for skiing, and easily picked up by the wind, but that won’t hold together when formed into a snowball.

The second way to stick ice crystals together is to warm them up a bit. When ice crystals fall through a region of cloud or atmosphere where the temperature is slightly above freezing, the edges of the crystals start to melt. Just a tiny bit of liquid water allows ice crystals that bump into each other to stick together very efficiently, almost like glue.

The result? Large clumps of ice crystals falling from the sky, what we call a “wet snow” – less than ideal for hitting the slopes but perfect for building a snowman.

Snow formed in clouds typically reaches the ground only in winter. But almost all clouds, no matter the time of year or location, contain some ice. This is true even for clouds in warm tropical regions, because the atmosphere above us is much colder and can reach temperatures below freezing even on the warmest of days. In fact, scientists who study weather discovered that clouds containing ice produce more rain than those that don’t contain any ice at all.

Hello, curious kids! Do you have a question you’d like an expert to answer? Ask an adult to send your question to CuriousKidsUS@theconversation.com. Please tell us your name, age and the city where you live.

And since curiosity has no age limit – adults, let us know what you’re wondering, too. We won’t be able to answer every question, but we will do our best.

Alexandria Johnson, Professor of Atmospheric and Planetary Sciences, Purdue University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Curious Kids is a series for children of all ages. If you have a question you’d like an expert to answer, send it to curiouskidsus@theconversation.com.

Are animals smart? – Deron

It’s a fascinating question that intrigues millions of pet owners, animal lovers, veterinarians and scientists all over the world: Just how smart are animals?

Scientists once believed a brain with billions of neurons was a requirement for intelligence. After all, that’s why you’re able to think – neurons are the nerve cells in the brain that connect and transmit messages to each other.

For the record, the human brain has about 86 billion neurons. For comparison, dogs and cats have less than one billion.

Yet the more that scientists like me study animal emotion and cognition – the ability to learn through experiences and thinking – the more we find that humans are not very special at all. Many nonhuman species can do these things too.

Right now, there’s no agreement on how to decide whether a particular animal species is intelligent. But most scientists who study animal cognition have observed that many animals are able to solve problems, use tools, recall important information about their environment and recognize themselves in the mirror.

Toolmaking bears and crows

Memory is a marker of intelligence. Of all animals, humans possess the most accurate and sophisticated memory. But elephants can recognize as many as 30 traveling companions at a time. They also learn to migrate away from drought-prone areas, based on memories of earlier droughts.

That kind of recall – known as episodic memory – is the ability to remember an event, including when and where it occurred. Until recently, scientists thought only humans had it. But now researchers have learned that some birds, cats, rats, monkeys and dolphins have it too.

Animals may not remember every experience – neither do people – but they do recall things critical to their survival. For example, birds know where they stored food. Monkeys know the presence of a predator.

Scientists once thought tool use was an exclusively human ability, but that’s not so. Chimpanzees use sticks to catch termites and stones to crack nuts open. Crows can even manufacture tools. By bending a wire, they can make a hook to retrieve a food reward that’s otherwise out of reach.

Researchers presented eight captive brown bears with this food challenge: Three objects – a large log, a small log and a box – were placed in an outdoor enclosure. A food reward was suspended above them. Six of the eight bears were able to move the logs and box into positions that enabled them to fetch the reward. Essentially, they used the three objects as tools.

Dolphin, chimpanzee communication

Language is another measure of intelligence. People, of course, have enormously sophisticated communication skills. But dolphins have complex dialects in the form of crackles, squeaks and whistles. Many researchers say the noises are a language. Chimpanzees and gorillas have used sign language to express emotions and ask for things from people.

Self-awareness – the ability to recognize yourself as an individual – signals intelligence. Babies don’t recognize themselves in the mirror until they are about a year and a half old. Up until then, they probably think the mirror image they see is another baby.

Many other species, including dolphins, ravens and elephants, recognize themselves in the mirror. Researchers put a red dye mark on chimpanzees under anesthesia; once awake, the chimps saw their reflection in a mirror. Instead of touching the red mark on their reflection in the glass, they touched the red mark on themselves, indicating self-recognition.

Just because animals can’t do certain things, it doesn’t mean they’re unintelligent. After all, humans can’t fly like a bird or swim like a fish. Nor is there a need for us to have the incredible sense of smell a dog has. We’d be sniffing hundreds of different smells from miles away – the scents from perfumes and pollution, gardens and garbage. From an evolutionary standpoint, that wouldn’t help us much. Plus, we’d get sick of it very quickly.

But all animals, including humans, have developed a wide range of capabilities so they can succeed in the environment they live in. Put simply, we’re all using our brains. Now that’s intelligent.

Hello, curious kids! Do you have a question you’d like an expert to answer? Ask an adult to send your question to CuriousKidsUS@theconversation.com. Please tell us your name, age and the city where you live.

And since curiosity has no age limit – adults, let us know what you’re wondering, too. We won’t be able to answer every question, but we will do our best.

Leticia Fanucchi, Clinical Assistant Professor of Veterinary Clinical Sciences, Oklahoma State University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Curious Kids is a series for children of all ages. If you have a question you’d like an expert to answer, send it to curiouskidsus@theconversation.com.

Why is water different colors in different places? – Gina T., age 12, Portland, Maine

What do you picture when you think of water? An icy, refreshing drink? A crystal-blue ocean stretching to the horizon? A lake reflecting majestic mountains? Or a small pond that looks dark and murky?

You would probably be more excited to swim in some of these waters than in others. And the ones that seem cleanest would probably be the most appealing. Whether or not you realize it, you are applying concepts in physics, biology and chemistry to decide whether you should leap in.

The color of water offers information about what’s in it. As an engineer who studies water resources, I think about how I can use the color of water to help people understand how polluted lakes and beaches are, and whether they are safe for swimming and fishing.

Light and the color of water

Drinking water normally looks clear, but ponds, rivers and oceans are filled with floating particles. They may be tiny fragments of dirt, rock, plant material or other substances.

These particles are often carried into the water during storms. Any rainfall that hits the ground and doesn’t go into the soil becomes runoff, flowing downhill until it reaches an open body of water and picking up loose materials along the way.

Particles in water interact with radiation from the Sun shining on the water’s surface. The particles can either absorb this radiation or reflect it in a different direction – a process known as scattering. What we see with our eyes is the fraction of radiation that is scattered back out of the water’s surface. It strongly affects how water looks to us, including its color.

Depending on the properties of the particles in our water sample, they will absorb and scatter radiation at different wavelengths. The light’s wavelength determines the color we see with our eyes.

Waters that contain lots of sediment – such as the Missouri River, nicknamed the “Big Muddy” – backscatter light across the yellow to red range. This makes the water appear orange and muddy.

Cleaner, more pure water backscatters light in the blue range, which makes it look blue. One famous example is Crater Lake in Oregon, which lies in a volcanic crater and is fed by rain and snow, without any streams to carry sediment into it.

Deep waters like Crater Lake look dark blue, but shallow waters that are very clear, such as those around many Caribbean islands, can appear light blue or turquoise. This happens because light reflects off the white, sandy bottom.

When water contains a lot of plant material, chlorophyll – a pigment plants make in their leaves – will absorb blue light and backscatter green light. This often happens in water bodies that receive a lot of runoff from highly developed areas, such as Lake Okeechobee in Florida. The runoff contains fertilizer from farms and lawns, which is made of nutrients that cause plant growth in the water.

Finally, some water contains a lot of material called color-dissolved organic matter – often from decomposing organisms and plants, and also human or animal waste. This can happen in forested areas with lots of animal life, or in heavily populated areas that release wastewater into streams and rivers. This material mostly absorbs radiation and backscatters very little light across the spectrum, so it makes the water look very dark.

Bad blooms

Scientists expect water in nature to contains sediments, chlorophyll and organic matter. These substances help to sustain all living organisms in the water, from tiny microbes to fish that we eat. But too much of a good thing can become a problem.

For example, when water contains a lot of nutrients and heats up on bright sunny days, plant growth in the water can get out of control. Sometimes it causes harmful algal blooms – plumes of toxic algae that can make people very sick if they swim in the water or eat fish that came from it.

When water bodies become so polluted that they threaten fish and plants, or humans who drink the water, state and federal laws require governments to clean them up. The color of water can help guide these efforts.

My students and I collect water samples at High Rock Lake, a popular spot for swimming, boating and fishing in central North Carolina. Because of high chlorophyll levels, algal blooms are occurring there more often. Residents and visitors are worried that these blooms will become harmful.

Using satellite photos of the lake and our sampling data, we can produce water quality maps. State officials use the maps to track chlorophyll levels and see how they change in space and time. This information can help them warn the public when there are algal blooms and develop new rules to make the water cleaner.

Hello, curious kids! Do you have a question you’d like an expert to answer? Ask an adult to send your question to CuriousKidsUS@theconversation.com. Please tell us your name, age and the city where you live.

And since curiosity has no age limit – adults, let us know what you’re wondering, too. We won’t be able to answer every question, but we will do our best.

Courtney Di Vittorio, Assistant Professor of Engineering, Wake Forest University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Curious Kids is a series for children of all ages. If you have a question you’d like an expert to answer, send it to CuriousKidsUS@theconversation.com.

How is a text-to-speech voice made? – Sarah G٫ age 11٫ Seguin٫ Texas

When you talk to computerized assistants like Siri or Alexa, they reply in voices that sound very human. But how do computers, smartphones and apps actually talk like a person? They use a technology called text-to-speech.

When you speak, your lungs push air up your windpipe and through the vocal cords in your throat. That makes the vocal cords vibrate, which creates sound. Your brain tells your mouth, tongue and lips to shape that sound into words.

I’m a computer engineer who researches how computers create realistic experiences for people. A computer simulates this process of making spoken words. It sends electrical signals to a tiny speaker, which vibrates really fast. The vibrations push against the air surrounding the speaker, creating sound waves. Software in the computer controls those electrical signals in order to shape the sound waves to create speech.

If a computer wants to say “Hello, how are you?” it breaks each word into bits of sound called phonemes. Phonemes are the smallest building blocks of speech, such as the sounds “sh,” “short i” and “p” to say “ship.” The software creates the phonemes and groups them in the correct order to form words: “Heh” “lo” “how” “r” “u”? The human brain and mouth create and connect phonemes, too.

Robot speech

Way back in the 1700s, inventors tried to make machines work like your lungs and throat do. They used bellows – a big bag that a person could squeeze – to push air from inside the bag through pipes, whistles and leather tubes. The sounds that came out were squeaky, weird and creepy.

The first electronic speech machines, called synthesizers, were built in the 1930s. One famous machine was called Voder, which made its debut at the 1939 World’s Fair in New York City. Voder looked like an organ. A person had to press electronic buttons, keys and foot pedals to get it to gasp out basic phrases like “Good morning!”

Computers began speaking by putting together phonemes in the 1960s, creating stiff, robotic speech.

Pieces to a puzzle

Old computer voices often sounded robotic and choppy, like “He-llo-hu-man-I-am-a-com-pu-ter.” This happened because older software programs had to stitch together small sounds that had been mapped out from recorded voices. The maps, called spectrograms, look like graphs with peaks and valleys representing how strong each tone was at each instance when a sound happened.

The programs put the maps together like pieces in a puzzle and turned them back into sounds. That method worked, but it sounded very unnatural.

Today’s computers use machine learning, a kind of artificial intelligence, to sound like a person. Engineers and scientists train an AI program by giving it many hours of recordings of real people talking. The machine learning software analyzes patterns in the speech. That includes everything from how people breathe to when they laugh and to how their voices sound higher when they get excited.

The patterns allow the computer to shape phonemes into words and sentences in all the subtle ways people do.

This advanced technology even allows a sophisticated AI computer to listen to a recording of your voice for just a few seconds, learn your exact speech patterns and copy it. It can then say sentences you have never actually spoken, in a voice that sounds just like yours.

Helpful and harmful voices

Text-to-speech software helps millions of people every day. In cars, it gives directions so drivers can keep their eyes on the road. It can read news articles and websites for people who are blind, and it can give a voice to people who cannot speak.

Like some other powerful technologies, the software can also be misused. Advanced software can create highly realistic fake voices, sometimes called audio deepfakes. These synthetic voices can sound almost identical to a real person’s voice by learning from a short sample of their speech.

Scammers can use this technology to impersonate family members, co-workers or celebrities. They can make phone calls or leave voice messages that try to fool people into believing bad information. Scientists and engineers are working to make tools that can identify fake voices to help stop scammers.

So the next time you hear a phone, computer or video game speak with a human voice, you know how it was able to it without having lungs, vocal cords, lips or a tongue!

Hello, curious kids! Do you have a question you’d like an expert to answer? Ask an adult to send your question to CuriousKidsUS@theconversation.com. Please tell us your name, age and the city where you live.

And since curiosity has no age limit – adults, let us know what you’re wondering, too. We won’t be able to answer every question, but we will do our best.

Tam Nguyen, Associate Professor of Computer Science, University of Dayton

This article is republished from The Conversation under a Creative Commons license. Read the original article.