Rivers in the sky

Atmospheric rivers are the largest freshwater transport mechanism on Earth

Serving as highways that carry the water vapor equivalent of up to 15 times the average flow of water at the mouth of the Mississippi River, atmospheric rivers are approximately 400 to 600 kilometers (250 to 375 miles) wide and provide 30-50% of the annual precipitation of the US West Coast.

The largest river on Earth is actually in the sky

High above the canopy of the Amazon rainforest drifts an airborne river fed by the towering trees below. The trees pull water from their roots into their trunks, pushing any excess water out of their leaves and into the atmosphere as vapor. Watch this six-minute video to learn how.

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.

How jet streams, which reside in the troposphere, shape and confine pockets of atmospheric air

These fast-flowing ribbons of air are hundreds of kilometers wide and typically travel from west to east due to Earth's rotation, with the polar front and subtropical jets serving as major drivers of global circulation. Warmer air near the equator pushes the polar front jets toward the poles, which can buckle and deform them as they contain frigid polar vortex systems.

Explore Earth's atmosphere and what its layers contain in this interactive adventure

In this interactive, users can move from Earth's surface up through its atmosphere, exploring the natural phenomena found in each layer, including atmospheric rivers, auroras, and meteor showers. Artificial structures such as weather balloons and the International Space Station can also be found on the adventure.

From evaporation to precipitation: An overview of the water cycle

The water cycle is a natural process that continuously circulates water throughout Earth's systems. View this diagram from NASA to understand how the water cycle incorporates evaporation, condensation, precipitation, and more. First, the sun's heat...

Visualize real-time and historical atmospheric conditions from around the world

This tool provides live maps of wind, rain, thunderstorms, and other atmospheric phenomena overlayed on an interactive map of the Earth. Users can enter their location to explore local atmospheric dynamics and review historical weather conditions dating back to 1979.

An overview of Earth's atmospheric cells and how they distribute Earth's uneven heating

The Hadley, Ferrel, and Polar cells are circulation patterns that act like gears, moving warmer air from the equator to the poles. The rising and falling of air currents within these patterns creates semi-persistent regions of low and high pressure, which contribute to the formation of regional climates, such as tropical zones.

Tiny water droplets can blur a rainbow's colors into a foggy white

When sunlight enters water droplets, it can reflect from the inside and spread out into different colors, producing a series of colorful arcs—supernumerary bows—which we refer to as rainbows. For droplets a few hundredths of a millimeter in size, these arcs overlap onto each other, producing fogbows of white light.

How trees transport water from roots to leaves

Trees move water to their extremities via a deft system starting from the roots to the leaves. See how it works in this short video breaking down the process in a Douglas fir.

Rain-catching tubes provide new hydropower source for tropical regions

An experiment in Singapore showed that charge separation could be established by rainwater flowing through narrow tubes. The separation, which creates a voltage, could be scaled up in regions of high rainfall to provide a clean energy source.

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).

Colorful thunderstorm phenomena can be viewed from the International Space Station

Transient luminous events are lightning-related phenomena that occur in the atmosphere above storm clouds. These events often look like columns of red light resulting from electrical discharge, but may also appear as purple tendrils or long blue jets.

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.

View a diagram of Earth's atmosphere, which is composed of five layers

Starting from the surface, the troposphere is home to Earth's weather, followed by the stratosphere, which houses the ozone layer, and the mesosphere, which burns up most debris from space. Above these layers lies the thermosphere, where auroras are produced, and the exosphere, which lacks a clear outer boundary as it fades into outer space.

Atmospheric processes amplify the strength of storms by coalescing clouds

Research has shown that turbulent mixing of air at the edges of clouds and other small-scale thermal activity beneath them help clouds group together, intensifying short bursts of rainfall, especially in tropical regions. Simulations reveal this produces more powerful storms than predicted by older models, though they may occur less frequently.

Explore a series of interdisciplinary explainers on climate science

From animations on the quantum mechanics of greenhouse gases to a photo essay on how scientists acquire climate data, this collection provides detailed explorations of how different branches of science have contributed to our understanding of climatology.

The conditions needed for cloud iridescence, or rainbow clouds

The relatively rare phenomenon occurs when sunlight scatters off tiny water droplets or ice crystals in thin, newly-forming or semi-transparent clouds, such as altocumulus, cirrocumulus, lenticular, and cirrus varieties. This effect is similar to what is seen in soap bubbles and mother-of-pearl shells and produces pastel-like colors.

A breakdown of Earth's atmospheric layers, including why it can get colder or hotter with altitude

Gases in the troposphere—the atmosphere's lowest layer—cool with increasing height as they get farther from the thermal energy emitted by Earth's warm surface. In the next layer—the stratosphere—ozone is increasingly heated by the sun's ultraviolet radiation with height. Because cooler air sinks and hotter air rises, the cooler troposphere and hotter stratosphere form a natural boundary keeping Earth's weather in the lowest layer.

Trade winds blow from east to west due to the Coriolis Effect

Warm air rises near the equator while cooler air sinks near the poles, creating circulation patterns that curve due to Earth's rotation. At the equator, doldrums—calm regions of no wind—build warm, moist air, creating storms.

Infographic illustrates the diverse and fragile Amazon ecosystems

This infographic helps readers better understand the vast rivers, forests, plants, and animals that call the Amazon rainforest home. Home to the largest collection of plant and animal species in the world, the Amazon rainforest has 16 thousand known...

All rainbows are 'raincircles' caused by water droplets separating white sunlight into a spectrum of colors, but Earth's surface blocks the bottom half of the circle from our line of sight.

Learn why water can take millions of years to be recycled via the hydrologic cycle

While a single drop of water spends an average of nine days in the atmosphere before precipitating back to Earth, it can spend thousands of years in the ocean before evaporating, and hundreds of thousands of years deep in rock layers before being released as steam in volcanic eruptions. Some water molecules have been trapped in Antarctic ice sheets for millions of years since they last moved through the water cycle.

View the various types of lightning

The most common form of lightning involves channels of electricity between oppositely charged regions within a cloud or between two clouds to reestablish electrostatic equilibrium. While cloud-to-ground lightning is understood best, research is ongoing to fully model the mechanisms behind rarer forms of lightning, such as transient luminous events.

Watch how scientists learn about hurricanes by flying into them

A specialized fleet of Air Force planes is built to fly into hurricanes and gather critical data from inside the storm. Beyond radar and microwave sensors, the planes are equipped with dropsondes—small instruments dropped into storms to measure pressure, temperature, and wind.

View the 55 ECVs used to describe Earth's atmospheric conditions

Essential climate variables include physical, chemical, and biological variables that meaningfully contribute to Earth's climate and how it changes with time. Many of these variables influence one another through feedback mechanisms across Earth's atmosphere, hydrosphere, cryosphere, biosphere, and geosphere.

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.

Rayleigh scattering of light gives the atmosphere its blue skies and red sunsets

Light is deflected from its original path by atmospheric particles, where bluer light is scattered more than other colors. When the sun is at its highest point in the sky, it travels through the thinnest part of the atmosphere, scattering some blue light across the sky. A greater atmospheric path length at sunset scatters more colors, leaving only red, yellow, and orange.

A simple pictorial explanation of ocean geography

Visualizing ocean geographical features, such as a coastal zone, continental shelf and abyssal plain. This article from the US Geological Survey also provides several links to diverse ocean facts.

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.

Tropical cyclones consist of three main parts: the eye, the eyewall, and rainbands

The eye is a calm, clear central area surrounded by an eyewall of intense thunderstorms. Rainbands are spiral bands of clouds and thunderstorms extending from the eyewall.

Transpiration drives water movement through a plant’s vascular system

Water evaporates from the leaves, creating tension that pulls more water upward from the roots through the xylem—the equivalent of plant blood vessels. This process is supported by water molecules sticking to each other (cohesion) and xylem walls (adhesion).

The weather time machine

A fun interactive on how old ships’ logs are giving scientists new insights into the past and future of the Earth’s changing climate (w/maps and pictures).

Clouds can be categorized into 10 basic types based on their height and composition.

Among the features of these types, cirrus clouds can display various colors at sunrise and sunset, while altocumulus clouds can produce a corona phenomenon around the sun or moon. Nimbostratus clouds are thick enough to block out the sun entirely.

Watch a visualization of how Earth's oceans impact its atmosphere, weather, and climate.

Tropical cyclone formation require warm water and limited vertical wind shear

Ocean temperatures above 27 degrees Celsius fuel rising, moist air, which releases energy through heat as water vapor condenses into clouds. Significant changes in wind speed with height can spread out these upflows, preventing the eventual formation of a central column known as the eye.

The Arctic warms more quickly than the rest of the planet because of the loss of surface ice, a lack of vertical air circulation, and the release of thermal energy as water vapor condenses.

View examples of rift valleys, the product of surface divergent boundaries

At these boundaries, tectonic plates move apart, stretching and thinning Earth’s crust as long valleys are formed from smaller, interconnected valleys and troughs. Ongoing rifting and erosion can further sink the valley, becoming a rift lake if volcanic activity becomes inactive.

Stratospheric balloons: a visual guide

In late January 2023, a Chinese high-altitude balloon, believed to be for surveillance purposes, traversed the US and caused a diplomatic stir. The technology itself is established—though typically used for atmospheric measurements. This visual...

Due to a local microclimate, a thunderstorm nicknamed Hector the Convector appears almost every day from September to March at around 3 pm off the northern coast of Australia.

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.

How salt, sunlight, and wind drive ocean currents

The Atlantic Meridional Overturning Circulation plays a critical role in regulating earth's climate, but is threatened by climate change. Explore the effects of temperature, density, and salinity on ocean currents in this 13-minute PBS video.

View the transition from laminar to turbulent flow

Using a dye released in the water, streamlines, which are parallel to one another and consistent at low flow velocities, become visible. As the water moves more quickly, viscosity cannot suppress the velocity change, and streamlines become chaotic, creating turbulence.

Differences in pressure and temperature between atmospheric gases create wind

Because Earth's surface is not uniformly heated by the sun at all times, pockets of warmer and cooler air will form and interact. Warmer pockets of less dense air will rise, leaving gaps for cooler, denser air to move in. Wind is this movement of air from high-pressure to low-pressure areas.

Scientists use ground-based radar data to detect turbulence within clouds

NCAR developed the NEXRAD Turbulence Detection Algorithm and the Graphical Turbulence Guidance system to provide forecasts up to 18 hours ahead using ground-based Doppler radar data. Software systems also utilize an automated observation and reporting package—the EDR system—found on Delta, United, and Southwest Airlines aircraft.

Why we have different seasons

Visualize just how exactly seasons come to be with this animation of the earth in relation to the sun, and see how earth's tilt determines our seasons.

Watch a visualization of global ocean currents from NASA's Estimating the Circulation and Climate of the Ocean project.

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

While El Niño moves warm Pacific Ocean waters east along the equator, La Niña moves them west, shifting where rainfall will become more common for months.

Watch a lightning storm from the International Space Station

While passing over the Alabama and Georgia regions, NASA astronauts photographed passing thunderstorms from the ISS. The illuminated clouds are described as "nebula-like formations."