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.

While landslides are associated with the downward flow of unstable terrain, the term encompasses a variety of geological processes, which are distinguished by how the material moves and what materials are involved.

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.

After a landslide, repeat activity may follow the appearance of cracks, springs of water, or dirt, sand, and rocks tumbling down from scars—exposed portions of Earth where the initial landslide began.

Explaining the icy mystery of the Dyatlov Pass deaths

A decades-old mystery from Soviet Russia could be explained by studying the science of snow. After nine students died on a hiking trip in the Ural Mountains, Soviet investigators found six had perished from hypothermia while three others died from blunt force trauma. The mystery confounded officials for years, and rumors of yeti attacks and similar theories abounded until researchers proposed a new potential culprit: an avalanche.

In the US, flash floods—rapid floods that occur within six hours of rain—kill more people than tornadoes, hurricanes, and lightning.

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.

See how the Winter X Games course is built

Winter X Games courses are custom-built over weeks, with crews moving thousands of tons of snow to create features like halfpipes and jumps—incorporating athlete input to ensure challenging designs that push progression and safety.

Although the term 'glacial pace' is associated with the slow movement of glaciers, during glacier surging, these massive bodies of ice can move over 60 meters (200 feet) a day.

The complex science of snow removal

Plowing snow seems simple, but its actually a technically complex task and requires significant logistics, patience, and funding. New York City's 19,000 miles of roads require days to plow at a cost of $12M per inch of fallen snow, and roughly 17 million tons of salt were applied to road surfaces across the US in a recent year. Dive into the details of snow removal with an in-depth and funny video.

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.

Why do flash floods occur?

Flash flooding can be more dangerous than traditional floods, occurring within the span of hours and exhibiting rapid currents. Here's how atmospheric conditions and geography combine to make some locations ripe for the disaster.

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.

Hydroplaning occurs when a vehicle's tires lose traction on wet roads

Water depth must be over 0.1 inches, and vehicle speed must exceed 50 mph for hydroplaning to occur. Tire wear, size, and tread patterns affect the likelihood of hydroplaning, which is more common for all-wheel drive vehicles.

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.

Hurricane Helene dumped enough water to fill Lake Tahoe

Alongside a rainstorm that moved into the region ahead of it, the hurricane released an unprecedented 40 trillion gallons of rain on the southeastern US, causing catastrophic flooding and at least 100 deaths. Meteorologists suggest climate change is exacerbating the severity of such events.

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.

Rather than being triggered by a massive displacement of water from a geological event, meteotsunamis are caused by rapid changes in air pressure from fast-moving weather systems.

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.

Research shows that cosmic rays may trigger the cascade of displaced electrons needed to produce lightning, which is also enabled by pointed ice crystals that create strong electric fields.

Storm surges, not winds, are the leading cause of hurricane-related fatalities

A storm surge is an abnormal rise in water levels generated by a storm that exceeds predicted tides. It is particularly dangerous in coastal regions, where it can generate extreme flooding well before the hurricane makes landfall.

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.

Snowfall records from every county in the US

Discover the one-day snowfall records of every county in the US in this comprehensive map. Data from the National Oceanic and Atmospheric Administration captures inches of snowfall and the year it fell the most in each county. See the contrasts between the inches of snowfall in warm southern American states and the cooler East Coast.

Although earthquakes cause about 80% of tsunamis, almost all earthquakes lack sufficient energy to cause the sudden shift in the ocean floor needed to substantially displace enormous volumes of water.

Airports at high elevations, like Denver International Airport, have longer runways than most airports because airplanes cannot take off or land as quickly in thinner air.

The fragility of the alpine tundra

This article takes readers into Rocky Mountain National Park's Alpine Tundra, an area above the tree line where only specially adapted plants can survive. One such plant is the cushion plant, which avoids strong winds by growing close to the ground...

There are no outdoor locations that are safe from lightning

If your hair stands up amid an approaching storm, seek shelter immediately, as a local buildup of charge imbalance precedes cloud-to-ground lightning. If you are stuck outside, move to a lower altitude, such as a valley or ravine, and avoid open fields, water, and isolated tall objects. Do not lie down or crouch.

Favorable conditions for wildfires are becoming more frequent in the western US

A new study of the American West shows that climate change is driving more days that are hot, dry, and windy—the perfect conditions for deadly wildfires.

An interactive trek up Mount Everest

At just over 29,000 feet, Mount Everest is the highest summit on Earth and the premiere destination for serious climbers. The imposing peak has also claimed at least 322 lives over the past century, or between four and five victims per year. This...

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

Rising wildfire smoke can create 'fire clouds'—towering clouds that can help combat fires through downbursts of rain or complicate firefighting efforts by triggering new fires via lightning strikes.

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.

Freezer burn is the result of moisture leaving ice cream, something that's easily avoidable.

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.

Between 2006 and 2021, 444 people died from lightning strikes in the US

The National Oceanic and Atmospheric Administration reports that the odds of being struck by lightning in one's lifetime are one in 18,864. Participation in outdoor activities during the summer months in Florida, Texas, and Colorado increases one's risk of exposure.

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.

The odds of getting seriously injured on a US roller coaster are one in 15.5 million rides taken

Understanding the mechanics of a ride can help explain why they are so safe. Lift hills, launches, and breaks are each crucial components of coasters and are designed to possess numerous safety features in case of any dysfunction.

Volcanoes 'die' when their supply of magma runs out, if they are shifted away from their underlying magma reservoir, or if they get clogged by collapsing or their magma cooling back into rock.

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.