The Life of Water: A Guide to the Water Cycle
The water cycle is a process in which water evaporates at ground level and rises into the atmosphere, after which it condenses into clouds and becomes precipitation. Once the water reaches the earth again, it is absorbed into the soil and runs off into our rivers, lakes, and oceans. From there, the cycle begins again. The heat of the sun and the effects of gravity fuel the entire process. The water cycle affects the planet’s weather patterns and helps to create a livable environment.
The Importance of the Water Cycle
The water cycle helps to make sure that water reaches every part of our ecosystem, including in the atmosphere and the oceans as well as deep in the earth. Living organisms, such as people, plants, and animals, require water to thrive and survive, and thus depends on its delivery. They also need nutrients, which the water cycle helps to move.
- King County: Hydrologic cycle as an ecological function
- National Geographic: Water cycle
- Center for Educational Technologies: The water cycle
The 4 Stages
The water cycle is made up of four stages:
Water evaporates when it is warmed by the heat of the sun. It becomes a vapor, which is a type of gas, and rises from soil, ice, lakes, streams, rivers, ponds, oceans, and other areas in which water can be found. After rising, the water begins to cool off and condense, at which point it reverts from a gas and turns back into a liquid. As a liquid, the water falls back to the ground in the form of precipitation such as rain, snow, sleet, or hail. The water then begins to collect in bodies of water and filtrates through soil to add to underground water levels.
- Idaho Department of Fish and Game: Water cycle
- Maine Government: Weather: The water cycle
- Environmental Protection Agency: Water cycle
3 States of Water
Water passes through three states:
In its solid form, water is frozen into ice. This begins when water reaches 0 degrees Celsius or 32 degrees Fahrenheit. In the process of becoming ice, it becomes less dense and can float to the surface of non-frozen water. This is why we can often find ponds and lakes with a layer of ice on the surface in colder climates during the winter.
Water as a liquid is the form that we are probably most accustomed to finding it in. It can be collected or flow across surfaces and it may absorb into porous materials and soil.
When water heats, it becomes a gas and releases into the air. We may see it as steam or as clouds, but unseen vapors are also present in the air that surrounds us. Water becomes a gas when the temperature of the water reaches 100 degrees Celsius or 212 degrees Fahrenheit. This heated vapor attaches itself to dust while it is in the air. In doing so, it forms into rain, snow, or hail depending on what temperature the atmosphere is as that time.
- University of Illinois: The states of water
- Purdue University: States of matter
- University of Wisconsin: Three states of matter: Solid, liquid, and gas
Where on Earth is Water?
Water can be found all over the planet. In fact, there are 326 million cubic miles of water. However, the distribution is uneven. In total, 99% of the earth’s water is below the surface. What remains above that still manages to cover 71% of the earth’s surface. Rainfall is heavy in some regions, while other regions get barely any at all, leading to an uneven distribution across the surface.
97% of the planet’s water (320 million cubic miles) is salt water that can be found in the oceans. The remaining 3% is fresh water, of which 69% is frozen in glaciers and another 30% can be found underground, with the last portion (0.5%) being located in fresh water sources that we can easily access such as rivers, lakes, and ponds.
- Penn State: Distribution of water on the Earth’s surface
- National Ground Water Association: Distribution of the Earth’s water
- Science X: What percent of Earth is water?
Additional Facts About Water
There are plenty of fun fact to learn about water!
- A leaking toilet can waste more than 22,000 gallons of water in just one year. That is equal to the amount of water required to fill a bathtub three times each day for the entire year.
- We use approximately 33% more water in the summer than we do during other seasons. A portion of this rise is due to the water required to keep grass watered and lawns healthy.
- Within the United states, we have approximately 10 million acres of lawn that potentially requires watering. The amount of water required is 270 billion gallons per week. That’s a fairly substantial amount when you realize that only 0.5% of the world’s water is currently drinkable.
- Water isn’t just good to drink. It is also a natural insulator and it helps to regulate the planet’s temperature.
- We are currently drinking water that may have been around during the era of the dinosaurs.
- Each person uses approximately 100 gallons of water per day.
- Even a short shower can use between 10-25 gallons of water.
- Bureau of Reclamation's Mid-Pacific Region: Water facts: World water supply
- Paul Minnesota: Fun facts about water
- Collier County: Interesting facts about water
- City of Columbus: Water facts
Lesson Plans and Resources for Teachers
Are you looking for lesson plans to use at home or in the classroom? Here are a few of our favorites:
Utah State University has several lesson plans that parents and teachers can use to teach K-6th students about the water cycle.
Benedictine College has a complete lesson plan on the water cycle that is aimed at 3rd grade students.
The Water Project has an awesome lesson plan for making a mini water cycle. This hands-on science project is simple and can be a lot of fun.