Viscosity is a fluid's resistance to flow, which varies with temperature

Lava flow viscosity plays a significant role in the type of volcano formed

Thin, runny flows spread quickly before cooling, producing expansive layers that build over time into wide shield volcanoes. The ejection and fast hardening of thicker lava flows and pyroclastic material create steep slopes and the characteristic cone shape of composite volcanoes.

The Reynolds number is the ratio of viscous and inertial forces in fluids

It can approximate fluid behavior in simple systems by non-dimensionalizing—removing the units within—the Navier-Stokes equations. A value close to zero indicates that the fluid will exhibit laminar flow, while a large number suggests that turbulence will occur.

Laminar flow moves in smooth, parallel layers, while turbulent flow is chaotic

In laminar flow, particles that make up a fluid move in consistent paths that do not cross each other. Contrastingly, differences across the speed of these particles cause them to mix, creating turbulence when viscosity cannot suppress the differences.

Friction is the force that resists the sliding of surfaces along one another

Friction always acts to resist movement and is determined by how rough the surfaces are and how hard they are pressed together. In the case of fluids, friction arises from the relative motion between adjacent fluid layers, which act like sliding surfaces.

The Navier-Stokes equations include the fluid version of Newton's second law

The first equation is the fluid version of the conservation of mass, which prevents incompressible fluids from gaining or losing matter. The second equation replaces acceleration and inertia, which is resistance to acceleration, with fluid pressure and viscosity.

The boiling temperature of water decreases with increasing elevation because the molecules need less energy to overcome the lower atmospheric pressure associated with thinner air.

The boiling temperature of water decreases with increasing elevation because the molecules need less energy to overcome the lower atmospheric pressure associated with thinner air.

Explore a simulation of ideal gas behavior, which can be explained by kinetic molecular theory

The theory describes particles as moving in random directions, with a distribution of velocities determined by the gas's temperature. The particles collide elastically like billiard balls, are negligibly small, and do not exert forces on one another. The gas laws can be derived from these principles using statistics or observed via this interactive.

Feels-like temperature indicates how our skin will feel

When the wind is moving faster, we tend to feel colder due to the so-called "wind chill," which cools our bodies by moving heat away from them and making water evaporate faster. On the other hand, high levels of humidity can make us feel 10 degrees warmer at times.

'Viscoelasticity' allows muscles to be elongated briefly after stretching

The protective tissues around skeletal muscles consist of elastic proteins like collagen. Stretching them expands their length while retaining strength, ideal for athletes.

How 'vibes' factor into scientists' decisions about using certain units

Although there are absolute quantities from which units can be defined, such as the speed of light and the corresponding light year for distance, the usefulness of units comes from their ability to easily communicate values, rather than how fundamental their origins are. For example, while Kelvin measures absolute temperature, Celsius is scaled to the temperatures of boiling and freezing water, making them more practical for everyday usage.

Temperature is a value that controls how predictable or creative an LLM's output is

In large language models, temperature adjusts the randomness in text generation by modifying how often words with lower probabilities are selected next in the sequence. Lower temperatures produce more obvious outputs while higher temperatures produce more creative responses.

An animated visualization of the distillation of crude oil into petroleum products

When crude oil is boiled, its constituent hydrocarbons turn into steam and rise through a distillation tower, where temperature decreases with height. Because different chemical vapors cool back into liquids at distinct temperatures, hydrocarbons naturally sort themselves by boiling point and can then be processed separately into distinct outputs.

The importance of volatile aroma compounds in the flavor quality of food

Processes such as air movement and heating cause food to lose aroma molecules, which studies have shown play a major role in our sense of taste. While losing these molecules to the environment leaves fewer to be processed during consumption to intensify flavor, it can also produce previously nonexistent aroma compounds or release previously trapped ones, altering or enhancing the food's flavor.

Why breathing helium, sulfur hexafluoride, and other gases changes your voice

The speed of sound varies depending on the properties of the material it travels through, including its density. Because helium is less dense than air, sound travels faster, altering the timbre of one's voice to be squeakier by enhancing its higher frequencies. In molecules that are heavier than air, low-frequency sounds are enhanced, producing a deeper voice.

Physicists detect the sound of heat in superfluids, theorized since 1938

Referred to as "second sound," the flow of heat in a superfluid resembles a sound wave bouncing back and forth. The heat-mapping techniques used to make the detection may improve the study of neutron stars and superconductors.

Research shows Venus would be hotter if some of its CO₂ were swapped out

The planet's atmosphere—whose density is 92 times that of Earth's—is 96.5% carbon dioxide. Since these molecules all capture the same subset of infrared radiation emitted from Venus's surface, radiation outside this range escapes, demonstrating the increased impact that diverse greenhouse gas composition has on planetary warming.

The difference between ice cream, gelato, sorbet, and Italian ice

Ice cream is made of eggs and is high in fat, served cold. Gelato, on the other hand, has more milk and less cream, and is typically served warmer than ice cream. Sorbet is dairy-free and often includes alcohol, while Italian ice is grainy, lighter, and low in calories (and often doesn't contain dairy).

The deadliest aspect of volcanic eruptions is often not lava, but pyroclastic flows—avalanches of ash, gas, and rock that can move more than half the speed of sound.

The marvels of mucus

Mucus—otherwise known as snot or phlegm—has a gross reputation, but the substance is actually of vital importance, lining the moist surfaces of our nose, intestines, lungs, and more. It plays a constant role in keeping our tissues from drying out and acts as a line of defense, but if it gets too sticky or thick, it can cause problems. Read about the marvels of mucus here.

Low temperatures led to the equipment failure that caused the Challenger disaster

The polymer chains that make up an O-ring give it the ability to quickly deform and fill in gaps to seal fluids, including the hot gases from the Challenger's rocket boosters. Cold weather on the day of launch stiffened the O-rings, reducing their flexibility and sealing properties.

How fermentation works

Alcoholic fermentation is the process where yeast transforms grape sugars into ethanol, creating wine. Microscopic fungi (commonly known as yeast) metabolize sugars, producing alcohol and carbon dioxide. Fermentation's speed and temperature impact wine's flavor and style: cooler temps suit fruity whites, while warmer ones enhance red's tannins. Fermentation stops when sugars are depleted or by temperature extremes, and sometimes yeast removal yields sweeter wines. Get a quick breakdown of the process with this easy explainer.

Inflation is a monetary phenomenon in which consumers see a broad rise in the prices of goods and services across the economy over time

Sustained periods of inflation are often caused by central bank policies including low interest rates or increased money supply. With more money chasing the same number of goods and services, prices tend to rise and the value of a single dollar drops.

Blood transports oxygen and vital nutrients throughout the body

Blood is the most vital substance in a body, ferrying oxygen, nutrients, and hormones to cells in need while regulating body temperature and collecting cellular waste and byproducts, such as carbon dioxide, for removal. Every adult human has over a gallon of the red liquid coursing through their veins.

VO2 max measures the body's ability to use oxygen to produce energy

VO2 max is the maximum rate at which the body can use oxygen to aerobically produce energy—adenosine triphosphate—for use during intense exercise. Aerobic exercise increases VO2 max, counteracting age-related decline by increasing the body's capillary count and remodeling the heart's left ventricle, increasing the amount of blood it pumps.

To reduce wrinkles in clothing, research recommends gentle wash cycles with more water and tumble drying with smaller loads and longer times.

Where you are located in a gravitational field affects how quickly you age

The closer something is to the center of a massive object, the greater the strength of the massive object's gravitational field as a result of space-time being depressed more severely. Time passes more slowly the deeper an object is in this gravitational depression, meaning objects in the universe naturally seek to age more slowly.

The price of gas is a composite made up of several different factors, with the federal gas tax making up less than 20% of what drivers pay at the pump.

Stars appear to twinkle because turbulence in the motion of molecules in Earth's atmosphere causes light to bend and wiggle rapidly on its way to the surface—a phenomenon called scintillation.

To reduce wrinkles in clothing, research recommends gentle wash cycles with more water and tumble drying with smaller loads and longer times.

Hurricanes, which rely on air consistently spinning in the same direction, cannot cross the equator because air curves in opposite directions north and south of it.

Chaos theory—informally known as the butterfly effect—is the reason why weather forecasts are presented with probabilities rather than certainties.

Pure water does not conduct electricity because this flow of energy requires the movement of charged particles, and water is a neutral molecule.

Scientists can determine Earth's past climate conditions by analyzing air trapped in microscopic bubbles within ice cores—columns of compressed snow layers that build up over hundreds of thousands of years.

Scientists testing how climate change affects plants found, in a years-long simulation study, that poison ivy grew 70% faster with the resulting extra carbon dioxide.

Most of the observable universe's volume consists of voids and supervoids—enormous regions of space with little to no galaxies, stars, or light.

The word 'jazz' evolved from 'jasm,' 19th-century American slang for 'energy'

Browse a detailed visual analysis of over 200,000 similes—comparisons that often use 'like' or 'as'—from popular fiction to see how frequently writers the same idiomatic expressions.

Ebola is a filovirus, meaning it resembles a thread under a microscope, though it sometimes twists and can resemble a bowl of spaghetti.

How fusion—which releases energy when two lighter atoms combine to form a heavier atom—differs from fission

Venture capital is a form of funding provided to early-stage companies with high growth potential, typically in exchange for an equity (or ownership) stake

Objects can be 3D printed with light by projecting 2D computerized tomography (CT) scans onto rotating cylinders of resin, which solidify upon exposure.

The rivalry between Alexander Hamilton and Thomas Jefferson centered on federalism—the question of how much power the federal government should hold relative to the states.

Gerrymandering works through two techniques: cracking opposing voters across districts to dilute their power, and packing them into a few to waste their votes in lopsided majorities.

The history of many kitchen appliances involves unexpected discoveries and applications, including wartime radar turned hamster defroster and replacing an 'ice king' with heat-stealing boxes.

Tattoos remain visible on your skin thanks to immune cells called macrophages

Iran's Revolutionary Guard Corps is independent of Iran's regular army and is one of the most powerful and influential military-political organizations in the Middle East.

Budweiser stores yeast derived from the original 1800s strain in a secret bunker, which only the Head of Yeast Management can access—not even the CEO

The Brothers Grimm were lawyers before they were storytellers, but became interested in fairy tales as they began investigating how rules and customs had been passed down through cultures.

Fast-casual restaurant Chili's is experiencing a resurgence, with its parent company recently reporting a nearly 32% increase in sales, thanks to passionate Gen Z fans on TikTok.