From evaporation to precipitation: An overview of the water cycle

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.

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.

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).

A chemical overview of water, whose uncommon properties help sustain life on Earth

The uneven distribution of charge in water molecules allows them to bond to each other and to surfaces, enabling them to move against gravity, including up plants through roots and stems. These bonds also keep water in a liquid state over a wider temperature range and make it less dense as it freezes. This causes ice to float and form an insulating layer for underwater ecosystems, from which all life originated.

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.

Rivers in the sky

A short introduction to atmospheric rivers, including a handy illustration on the science behind them, the phenomena that help transport water vapor from the tropics across the globe.

Visualize water's abundance across the solar system, and its relative rarity on Earth

Despite covering almost three-quarters of its surface, water only makes up about 0.12% of Earth's volume. Water in some of Jupiter's and Saturn's moons comprises a larger share of those celestial bodies and of the total water in the solar system. For example, Jupiter's moon Ganymede is believed to harbor almost nine times Earth's oceans beneath its icy shell.

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

Data from NASA satellites help view and explain global climate and weather patterns, such as El Niño and La Niña.

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.

How the sun heats the Earth

We all know it: Without the sun's heat, the Earth would be uninhabitable. So how does it work? The sun fuses roughly 600 million tons of hydrogen every second, the energy from which bursts out into space—including toward our planet. Our atmosphere...

Grasp the earth's orbit around the sun with this interactive

See why seasons exist with this interactive simulator. Toggle between different views of the earth in relation to the sun and watch as the earth's axis causes the sun to shine at different angles throughout the year, causing the weather to fluctuate and more. This simulator clarifies a process many take for granted.

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.

Cloud formation requires water vapor and condensation nuclei to build from

The nuclei—particles like dust, salt, and smoke—act like jumpstarts that water molecules can start to accumulate onto to form clouds. Condensation nuclei are about 1/100th the size of cloud droplets, which are mostly water.

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.

Accurate climate models incorporate calculus to account for complex feedback loops

The simplest models assume uniformity across the Earth, with incoming energy from the sun being offset by the planet's albedo, or reflectiveness, which prevents the radiation from being fully absorbed. Incorporating elements such as atmospheric layers, latitude bands, geographic variability, and emissivity yields coupled differential equations quantifying Earth's interconnected systems.

How the body produces urine

Things seem so simple when nature calls. But, how does the body actually produce the urine we so regularly and thoughtlessly expel? This detailed, comprehensive animation walks viewers through every step with precise illustrations, from the kidney's filters (known as nephrons) to the direct nerve connecting the bladder to the brain. See how the body does it here.

How solar systems form

Learn how our sun, the planets, and other solar system bodies came to be with these videos and an infographic from NASA. Use this resource to visualize how the solar system formed and to model and describe the process.

How do hurricanes form?

Tropical cyclones, also called hurricanes and typhoons, cause catastrophic damage when they strike land. This four-minute video explores the life cycle of cyclones—how atmospheric conditions, ocean temperatures, and the Earth’s rotation combine to create them, and how they are driven by winds and eventually weaken after moving over land.

An interactive guide to the cardiovascular system

The cardiovascular or circulatory system moves blood throughout the body, ensuring cells have necessary nutrients and removing any waste. Click through this interactive 3D guide to explore the system as it crisscrosses the body via arteries, veins, and capillaries. This guide also includes similar breakdowns of the body and its other processes.

Since 2022, two-thirds of data centers have been built in water-stressed areas

In residential evaporative cooling systems, 10% of consumed water is lost to evaporation compared to 80% in data centers. Although some companies have pledged to become water-positive—replenishing more freshwater than they consume—by 2030 through a transition to air cooling, only 10% of data center operators track water use across all their facilities.

How Oceans were formed

Nonprofit organization American Oceans briefly explains the formation of the oceans, which cover over two thirds of Earth’s surface. They were formed by centuries of rain from the condensation of Earth's original gasses.

Understanding the role of photosynthesis as a sink within the carbon cycle

Photosynthetic organisms are net carbon absorbers, pulling carbon dioxide from the atmosphere and storing it in organic compounds and within soil. Approximately one-third of humanity's carbon emissions are stored by these organisms.

A history of water on the moon

Is there water on the moon? In 2020, NASA's SOFIA mission confirmed the existence of water on the sunlit area of the lunar surface. Early astronomers mistook the dark spots on the Moon for oceans, but they are actually plains of dark, lava-produced...

An overview of hydropower

Hydropower, or the use of the natural flow of moving water to generate electricity, is one of the oldest and largest sources of renewable energy.

An overview of Venus, from its retrograde rotation to its volcanic surface

Boasting over 1,600 major volcanoes—more than any other planet in the solar system—Venus rotates in the opposite direction as Earth, potentially due to a major collision during its formation that flipped the planet upside-down. The planet's rotation also makes days on Venus last longer than its entire year.

The REM cycle happens around four to six times per night

Sleep is a natural process that is critical to maintaining life—a process conserved throughout evolution across just about any animal with a brain. Generally speaking, the first three stages involve increasingly deep phases of non-REM sleep, followed by a roughly 90-minute period of REM sleep that repeats throughout the night.

Water acts as a coolant and a moderator of nuclear reactions in reactors

Nuclear reactions within a containment structure boil water into steam, which drives a turbine that generates electricity. This water is then recirculated via pumps back into the containment structure to repeat the process, with reaction rates lowered by the insertion of control rods that absorb neutrons, which trigger reactions.

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.

While the sun's gravity keeps the planets in orbit, their gravity also pulls on the sun, causing it and everything else in the solar system to orbit around a mutual balance point called the barycenter—the true center of the solar system.

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.

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.

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

Learn how your body is, scientifically, like a firework with its own slow, controlled burn.

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

Visualize the path of every solar eclipse from 1900 to 2099 and see what each looks like when observed from different locations on Earth.

How Amazon operates a 'flywheel' business model, a self-reinforcing cycle that drives continuous growth

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.

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

The use of fungi to detoxify land and water—a process known as mycoremediation—has been used to clean up natural resources affected by the 2025 California wildfires.

See how each of the more than two million known species relates to each other—and to common ancestors—in this zoomable tree of life.

Researchers believe the brain consolidates memories, processes emotions, and plans for the future during dream states

An initial public offering or 'IPO' is the process of a private company becoming public by putting shares of the company on the stock market for purchase.

The US dollar is the most widely circulated currency in the world, and is involved in nearly 90% of global transactions

For centuries, Niagara Falls has been a magnet for daredevils seeking to conquer one of nature's most powerful wonders, with its 200-foot drop and water rushing at 32 feet per second with 280 tons of force.

Hear 50 years of iconic hip-hop samples, the genre's foundational looped tracks

Take a 3D tour of the Hajj, Islam's annual pilgrimage to Mecca, undertaken by over 1.5 million Muslims.

The syncytiotrophoblast is the outer layer of the placenta and the largest human cell, spanning an area about twice that of a king-sized bedsheet.

Apollo astronauts left items in the moon's 'toss zone,' including golf balls, family photos, and bags of human waste, to make room for lunar rocks.

Trace how the Bill of Rights, inspired by centuries of political theory, took shape between 1774 and 1789.

See the evolution of Ebola vaccine and treatment development.