THE WATER CYCLE ON EARTH

Water never stops moving—through sky, land, oceans, and life itself

Water is Earth's most amazing traveler. It evaporates from oceans, rises as invisible vapor, condenses into clouds, falls as rain, flows through rivers and soil, and begins its journey all over again. Every drop of water you drink has cycled through clouds, mountains, and maybe even dinosaurs. Understanding the water cycle helps us understand weather, climate, and life on Earth.

What Is the Water Cycle?

The water cycle is the continuous movement of water from Earth's surface to the atmosphere and back again. Water travels through oceans, air, land, plants, and animals in an endless loop powered by the Sun's energy.

This cycle has no beginning or end. The same water molecules that fill today's oceans have cycled through clouds, rainfall, rivers, and living things for billions of years. Every raindrop, snowflake, and breath of humid air is part of this ancient, ever-moving system.

Key Idea: The water cycle is one of Earth's most important natural processes. It distributes fresh water across the planet, shapes weather and climate, and makes life possible.

How Does the Water Cycle Work?

Animated Water Cycle

Follow one water molecule as it moves through all six stages. Pause the loop, step forward or backward, and compare how temperature and state change at each stop.

Current stage Evaporation
Water state Liquid to gas
Temperature Heating above 100°C

Click any stage button to jump the hero diagram, compare before/after states, and zoom to that part of the cycle.

Stage 1: Evaporation

The Sun heats liquid water in oceans, lakes, and rivers. The water gains energy and transforms into invisible water vapor, rising into the atmosphere. Plants also release water through their leaves in a process called transpiration, which is sometimes counted as part of evaporation.

What happens: Heat + liquid water = invisible water vapor that floats upward

Ocean/Lake Water Vapor

States of Water

Water can exist in three states: solid, liquid, and gas. The state depends on temperature and pressure. Understanding these states helps explain what happens to water as it moves through the cycle.

Phase Change Explorer

Molecular Motion

Solid: Ice cube
Liquid: Cup of water
Gas: Steam

Solid (Ice)

Below 0°C (32°F)

ICE

Water freezes into solid ice. Molecules are tightly packed and move very slowly. Ice floats on water and stores energy.

Liquid (Water)

0°C to 100°C (32°F to 212°F)

WATER

Most familiar state. Molecules move freely and flow. This is how water travels through oceans, rivers, and rain.

Gas (Water Vapor)

Above 100°C (212°F)

VAPOR

Invisible gas state. Molecules are spread far apart and move very fast. Water vapor floats in the air all around us.

Phase Changes: Melting (ice → water), Evaporation (water → vapor), Condensation (vapor → water), Freezing (water → ice). The water cycle involves all these changes!

The Sun Powers the Cycle

Without the Sun, there would be no water cycle. The Sun's energy heats water, turning it from liquid into vapor. This heat drives wind and weather patterns. The Sun is the engine that keeps water moving around our planet.

Sun Heat Evaporation Wind Clouds Rain Solar Energy Drives the Cycle How it works: 1. Sun heats water → evaporation (liquid to vapor) 2. Heat causes air currents and winds → water vapor rises 3. Rising vapor cools → condensation → clouds → precipitation

Where Water Goes

Water on Earth is found in many places. Most of it is in oceans (salty), but freshwater is stored in glaciers, groundwater, lakes, and rivers. Plants and animals also hold water. Understanding where water is helps us use this precious resource wisely.

Hover or tap a slice to see details.

🌊

Oceans

97% of Earth's water

Saltwater covers most of the planet

❄️

Glaciers & Ice

~2% of all water

Frozen freshwater in polar regions and mountains

🔵

Groundwater

Most accessible freshwater

Stored in soil and rocks underground

💧

Lakes & Rivers

Freshwater on the surface

Source of water for humans and ecosystems

🌱

In Plants

Absorbed from soil

Used for growth and released through transpiration

🦁

In Animals

Essential for all life

Makes up 60-70% of living organisms

See It in Action

Adjust the environment and watch the cycle respond in real time. Stronger sunlight speeds evaporation, humidity boosts cloud formation, and seasons change how quickly water moves through the system.

Atmosphere6%
Oceans74%
Underground20%

Transpiration Explorer

Trace water from roots to leaves and back into the atmosphere. Plants are active participants in the water cycle, not just passengers.

Roots Absorb liquid water from soil.
Stem Moves water upward through tiny tubes.
Leaves Release vapor through stomata into the air.

Vocabulary

Evaporation

The process by which liquid water turns into water vapor and rises into the atmosphere. Heat from the Sun powers this process.

Condensation

The process by which water vapor cools and changes back into liquid water droplets. This forms clouds and fog.

Precipitation

Water that falls from clouds to Earth in the form of rain, snow, sleet, or hail. The process returns water to the surface.

Collection

The gathering of water in oceans, lakes, rivers, and soil. Collected water is stored until it evaporates again or infiltrates into the ground.

Infiltration

The process by which water soaks into the soil and moves downward through soil layers. This water becomes groundwater.

Transpiration

The process by which plants release water vapor from their leaves. Combined with evaporation, it's called evapotranspiration.

Groundwater

Water stored beneath Earth's surface in soil and rock layers. It fills aquifers and feeds springs and underground streams.

Water Vapor

The invisible gas form of water. It floats in the atmosphere and becomes visible as clouds when it condenses.

Quick Check

Test your understanding of the water cycle with these questions. Choose the best answer for each.

0/8 correct Question 1 of 8

Scavenger Hunt Challenge

Use the information from this page to answer these questions. Great for classroom activities!

0/6 correct Follow the hints to verify each answer

🔍 Challenge 1

Question: List the six main stages of the water cycle in order.

Hint: They start with E, C, P, C, I, and T.

🔍 Challenge 2

Question: What role does the Sun play in the water cycle?

Hint: Check the "Sun Powers the Cycle" section.

🔍 Challenge 3

Question: How much of Earth's water is in the oceans? What percentage is freshwater?

Hint: Look at the "Where Water Goes" section.

🔍 Challenge 4

Question: What is the difference between evaporation and transpiration?

Hint: One comes from water bodies, the other from living things.

🔍 Challenge 5

Question: Describe what happens to water during condensation. What causes it?

Hint: It's the opposite of evaporation. Think about temperature.

🔍 Challenge 6

Question: What is groundwater, and why is it important?

Hint: Check the vocabulary and "Where Water Goes" sections.

Wonder Zone: Beyond the Basics

The water cycle is even more fascinating when you explore its connections to weather, climate, and life. Here are some mind-bending ideas:

🧊 Glaciers: Frozen Storage

Glaciers are massive reservoirs of freshwater. As Earth's climate warms, glaciers melt, returning ancient water to the oceans. This affects sea levels and regional water availability.

💧 Aquifers: Underground Reservoirs

Groundwater fills hidden aquifers beneath our feet. Some aquifers took thousands of years to fill and provide crucial freshwater for drinking and farming. We must use them wisely.

⛈️ Severe Weather

The water cycle fuels hurricanes, tornadoes, and thunderstorms. Warmer oceans evaporate more water, which can intensify storms and change weather patterns globally.

🌍 Climate Change & Drought

Changes in temperature affect the water cycle. Some regions experience more rain, while others face severe droughts. Understanding the cycle helps us predict and adapt to climate change.

🪐 Water on Other Planets

Scientists search for water on Mars, icy moons, and distant exoplanets. Water may indicate past or present life. Earth's water cycle is unique and precious in the cosmos.

🧬 Water in Living Things

You are about 60% water! Plants are up to 95% water. Every organism on Earth depends on the water cycle. The water in your body has cycled through clouds, rivers, and dinosaurs.