Avalanches, which kill an average of 27 people in the US each year, typically require mountain slopes between 30 and 45 degrees and a layer of sturdy snow atop a weak, unstable layer, which can be put into motion by a trigger.

Avalanches happen when layered snow fails, often on perfect ski slopes

Snowpacks form unstable layers as weather shifts; a weak, refrozen layer buried under fresh snow can shear and release a slab avalanche on certain steep slopes. Triggers range from new snowfall to the movement of skiers, while survival depends on the presence of ski partners, beacons, and rescue teams.

Hail forms in freezing temperatures thousands of feet above the ground

Even if surface temperatures are well above freezing during the summer, updrafts during thunderstorms can push raindrops high into the atmosphere, where they can freeze and form hail. Giant hailstones the size of softballs require updrafts of close to 100 mph.

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.

Nor'easters can produce thundersnow—lightning in blizzard conditions

Although thunderstorms typically require warm air to rise in updrafts and collide with heavier soft hail, which creates charge separation and eventual electrical discharge, these cyclones can replicate these conditions by churning the atmosphere through strong winds. Rarely, especially warm lakes can similarly help generate thunderstorms during the winter.

During glacier surging, these bodies of ice can move over half a football field a day

The movement of these glaciers, which repeatedly speed up and advance for months or years after stalling or moving backward for a time, results from melting ice that reduces friction between them and the ground, allowing them to slide more quickly. Scientists note that this effect is becoming more frequent due to climate change.

The steep and slippery Russian ice slides sparked centuries-long obsessions with thrill-seeking

When a French traveler happened upon the 17th and 18th century Russian pastime of sledding down man-made hills, he brought the idea home and inspired others to modernize the mechanics. Adoration for coasters spread around Europe and eventually reached the US, where the scream machine would undergo major advancements.

What causes hail?

Hail can be a particularly destructive element of certain thunderstorms, occurring even during otherwise warm days. Learn about the dynamics that lead to ice chunks falling from the sky.

The ingredients that make up severe weather

A seven-minute video illustrating how a storm is made. These factors—moisture, instability, lift, and shear—are explained through a series of data sets and creative, descriptive diagrams.

Explosive volcanic eruptions happen when magma pressure overcomes rock strength

Magma usually stays underground because of a balance between its upward pressure, the weight of the Earth’s crust above, and the crust’s rock strength. Landslides can reduce crust weight, while built-up gas pressure can strengthen magmastatic pressure.

Volcanic ash is composed of fragments of volcanic rock, minerals, and glass

These abrasive particles are hazardous to aircraft. They can melt within engines and re-solidify on turbine blades, preventing forward propulsion. If inhaled, chemicals within ash can be toxic, and the particles can embed themselves into the lungs' ducts, causing suffocation.

Eruption forecasting relies on probabilistic methods resembling weather forecasting

While some volcanoes erupt with predictable signs, such as surface deformation from the build-up of underground magma pressure, others release magma at inconsistent rates. Extensive monitoring is needed to identify less clear patterns and indicators of future eruptions.

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.

Is ice slippery because of amorphization—a chaos of molecules caused by sliding?

Traditional explanations cite three factors that make ice slippery: pressure, friction and so-called premelting. A fourth has been proposed in recent years: amorphization, that sliding along some surfaces creates molecular disorder, causing liquid-like behavior.

Supervolcanoes can eject enough material to fill one-fourth of the Grand Canyon

Although extremely rare, their released material can trigger winters by blocking the sun and cooling the Earth’s surface for years. The Toba supereruption 74,000 years ago disrupted food chains and reduced the human population to a few thousand.

Dirty lightning is a thunderstorm created from friction between rising and falling flows of ash and smoke during volcanic eruptions.

Snowflakes form when water vapor turns directly into ice

Every water molecule has a slightly bent shape due to electron repulsion and regularly forms bonds with hydrogen molecules. When they freeze, they form a six-sided (or hexagonal) lattice, resulting in the six-sided symmetry of snowflakes. As the snowflake falls, more water molecules freeze onto its six sides, forming the unique, beautiful geometric designs.

Niagara Falls generates its own microclimate

Constant mist from the Falls produces localized weather effects, including rare ice formations that can rise over 100 feet high in winter.

Lightning is the sudden flow of electricity in the atmosphere as two oppositely charged regions seek to become balanced via the movement of electrons.

A 101 on the science and history of meteor showers

Bits of rock, ice, and dust flying through space called meteors burn up in a spectacular display when they hit our atmosphere 60 miles up at an average of 30,000 mph. Some of these are isolated objects, but others are recurring phenomena caused by...

Heat is the leading cause of death in natural disasters

Floods are a distant second, followed by hurricanes. That's according to data reported by the National Oceanic and Atmospheric Administration.

Crackling, popping, and rustling sounds have been reported during auroras

At the altitudes where auroras take place—between 100 and 300 kilometers (62 to 186 miles)—air is not dense enough to efficiently vibrate and carry sound waves to the ground. However, one theory suggests that the geomagnetic energy behind auroras can trigger electrical discharges near the surface, which may be the cause of reported sounds.

Permafrost—soil, rocks, and sand that are held together by ice and remain frozen for at least two consecutive years—covers about 15% of the Northern Hemisphere's land area.

Ski mountaineering—or 'skimo'—debuted at the 2026 Winter Olympics

The sport involves skiing both uphill and downhill, with sections where the skis are strapped to the athlete's back. Skiers start at the bottom with a carpet-like layer on their skis to help ascend, remove them for the final climb, and then step back into normal skis for a slalom-like descent.

Fast-changing conditions during their formation make tornado forecasting difficult

The final steps of tornadogenesis—the process of forming a tornado—depend on near-surface details, such as local geography, which are difficult for radar to observe and affect how funnel clouds make contact with the ground. Inconsistencies in storm behavior have limited the amount of advance warning people receive before tornadoes touch down.

Small elevation differences drastically protect homes in hurricanes

The construction of seaside homes has long involved building residences on elevated stilts, but this feature adds costs—and some elevated homes still fail. Explore the engineering behind the ideal height of a hurricane-proof building.

How cosmic rays and pointed ice shards help generate lightning in clouds

Although clouds generate electric fields as electrons are transferred when currents move past one another—not unlike building up static electricity by rubbing socks against carpet—these fields have been measured to be a tenth of the strength needed to make electricity strong enough to travel through air. However, pointed crystals are estimated to boost fields by factors greater than 10, and particles from outer space may help initiate cascades of displaced electrons.

Freezer burn is the result of moisture leaving ice cream

The ice cream death knell occurs when water crystals melt and then refreeze on the surface of the treat, creating a crunchy (but far from delectable) shell. The best way to prevent this unfortunate outcome is by storing your ice cream in a freezer that’s colder than 0°F.

High freezing speed restricts the development of gritty crystal chunks in ice cream

For this reason, ice cream does not maintain its smoothness when refrozen in a traditional freezer over several hours. The smooth texture is also made possible by balancing fat, sugar, and emulsifiers.

The intensity of auroral activity approximately follows the sun's 11-year cycle

The density, speed, and temperature of material ejected by the sun are at their lowest at the start of each cycle, resulting in weaker interactions with Earth's magnetic field and muted, diffuse auroras. While the average solar wind speed is about 300 kilometers (186 miles) per second, the fastest winds can be more than three times faster.

A fast explainer on every Winter Olympic sport

Slalom, luge, skimo: The 16 sports at the Winter Olympics aren't the most familiar to everyday audiences. They can be divided into three categories: track, indoor, and outdoor. This video breaks down each sport's rules and quirks and the variations of its events in less than eight minutes.

Lightning storms are more common in coastal and tropical regions

Water-abundant areas that receive increased solar radiation, such as those near the equator, experience increased rates of evaporation, which produce tall clouds as moisture rises, cools, and condenses. Mountain ranges can also steer air to higher altitudes, creating collisions between atmospheric particles that generate charge imbalances—the precursors to lightning.

Glacial ice loss can be determined by listening to escaping bubbles

Glaciers form from the accumulation of layers of snowfall over hundreds to thousands of years, trapping air bubbles that serve as time capsules of atmospheric conditions at the time. When glaciers melt, these bubbles produce a distinctive sound that can be detected by underwater microphones, allowing assessment of melting from a safe distance.

Learn all about different types of extreme weather

Find out in more detail about different types of extreme weather, from flooding to thunderstorms, from tropical cyclones to sandstorms, and more (w/ helpful videos).

Winter Olympic sports highlight various laws and principles of physics

Figure skaters leverage the conservation of angular momentum during spins by tightening their bodies, and the skintight suits used in ski jumping help reduce drag. Centripetal force allows speedskaters to make tight turns, while friction on skis helps ski mountaineers climb slopes. No action can violate the conservation of energy.

Instabilities in the polar jet stream can bring cold Arctic air southward

The polar jet stream marks the boundary between mid-latitude air and the much colder polar air, which are normally contained by the polar vortex—a ring of strong winds that circles the Arctic around 16 to 50 kilometers (10 to 30 miles) above the Earth's surface. Climate change may be responsible for "blocking patterns" that distort the jet stream, allowing polar air to leak into lower latitudes.

Tornadoes produce inaudible signals to humans hours before forming

Researchers at the National Oceanic and Atmospheric Administration have found that tornado-producing storms generate specific sounds below the range of human hearing, much like the infrasonic signals produced by earthquakes and avalanches. Although difficult to distinguish from wind noise, scientists hope to build systems that use these signals to improve tornado forecasting.

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.

Bomb cyclones can produce heavy rain, blizzard conditions, and intense winds

Known as "bombogenesis" in meteorology, these systems get their colloquial name from their rapid intensification over a 24-hour period—a phenomenon seen in some tropical cyclones. They occur most commonly along the coasts of the Northeast and Northwest US when there is a severe temperature difference between colliding air masses.

Climate change is increasing the frequency and intensity of severe turbulence

Severe turbulence over the North Atlantic has increased by 55% over the past 40 years, driven by strengthened jet streams and storm systems. Ongoing increases in global temperatures, which fuel these changes, may triple severe turbulence incidents in the coming decades.

Lightning forms when streams of rising and falling charged particles connect

In cloud-to-ground lightning, a buildup of negative charge at the bottom of clouds repels electrons on Earth's surface, leaving behind positively charged particles. When descending negatively charged air—the stepped leader—meets rising positively charged particles—the upward streamer—brightening runs up the connection, producing intense flashes known as return strokes.

Pilots are familiar with multiple types of turbulence, each with varying severity

Each type is defined based on what disrupts airflow in the atmosphere, including thunderstorms, mountains, and wakes produced by aircraft that previously took off. Pilots classify turbulence as light, moderate, severe, or extreme based on how it affects aircraft movement.

The air around lightning can be five times hotter than the sun's surface

The rapid discharge of electricity—flowing electrons—between oppositely charged regions across a narrow filament can raise temperatures to 30,000 degrees Celsius (54,000 degrees Fahrenheit). If lightning strikes a tree, the speed of the temperature spike can almost immediately turn all its water into pressurized steam, causing it to explode.

Interactions between solar storms and Earth's magnetic field create auroras

Solar storms on the Sun's surface produce clouds of electrically charged particles, some of which make their way to Earth. Those trapped in Earth's magnetic field accelerate toward the north and south poles, colliding with atmospheric atoms and molecules in the process, which produces light.

How search and rescue teams remove survivors from rubble

At any time, large-scale seismic activity can devastate entire regions, often with little warning. Emergency responders, then, are perpetually on call. This is particularly critical in areas with poor infrastructure.

Explaining the Leidenfrost effect, where water can hover and move against gravity

Water droplets can glide across surfaces whose temperatures are well above water's boiling point. This heat instantly vaporizes the bottom of the droplet, creating a layer of steam that the rest of the droplet rides and bounces upon. This can be seen when sprinkling water on skillets to determine if the surface is hot enough to cook on.

The importance of the mesosphere, the coldest part of Earth's atmosphere

Atmospheric gases are dense enough in this region to begin burning up debris traveling toward Earth's surface, producing meteor showers, or shooting stars. Although we normally associate decreasing temperatures with increasing altitude, temperatures increase beyond the mesosphere layer due to the absorption of high-energy ultraviolet radiation and X-rays.

Thunder occurs when fast-flowing electricity heats and pressurizes air, causing it to expand and produce a shockwave at each point along the bolt at multiple frequencies.

Tornado formation relies on wind shear to create a tube of rotating air

Once a horizontal vortex is created by air circulating between winds of different directions and speeds, an updraft, such as those seen in powerful thunderstorms, tilts the vortex vertically. The updraft then strengthens the vortex, which becomes a tornado upon touching the ground.

Though less common, tornadoes can form without the presence of thunderstorms

Supercell tornadoes involve rising warm air—updrafts—from the strongest type of thunderstorm—supercells—to help turn horizontally rotating tunnels of air into vertical columns. In non-supercell tornadoes, which are generally weaker as a result of forming within less energetic systems, vertical rotation is present from the start near ground level.

The National Weather Service communicates tornado risks on a three-tier system

During a tornado watch, atmospheric conditions favor the development of a tornado, and residents in an area should be prepared to seek refuge. A tornado warning is issued if a tornado has been detected, while a tornado emergency indicates a violent tornado has touched down in the area, with severe threats to human life and property expected.