The Water Cycle What is the Water Cycle? The water cycle is the movement of water from land to water to the atmosphere and back again over billions of years. Take a look at the picture below. Do you notice how the cycle has no start or end point? It goes around and around and around! Why Does Water On Earth Move In A Cycle? The amount of water on Earth never changes. This amount of water has cycled from one form to another for 5 billion years! It can be a gas, a solid or a liquid. That is because the earth is a closed system, meaning that no water can go in or out. So all the water on Earth goes through a cycle, around and around, but always remains on Earth. Closed System – An area by itself where things like water can’t come in or leave. Processes of The Water Cycle 1) Evaporation: This happens when sunlight heats the water in ocean, rivers, lakes or even your swimming pool, and turns it from a liquid state to a gaseous state called water vapor. 2) Evapotranspiration: Plants absorb water from the soil through their roots so they can grow. The water travels through the entire plant, reaching the leaves. The leaves have small openings called stomata, that open to let water out and carbon dioxide in. When the stomata of the plant are open, water evaporates from the leaves and turns into water vapor in the air! You can think of this process as a plant sweating! 3) Condensation: When water vapor in the air rises, gets cold and turns into a liquid! This water vapor can condense into clouds! 4) Precipitation: Is when water falls from the sky to the ground either as rain (liquid), hail or snow (solid). Precipitation happens when the clouds get so heavy because so much water has condensed, that the water falls. These clouds can move around all over the earth, travelling from one place to another. 5) Infiltration: Is when water soaks into the ground and all the way down through the layers of soil and rock to reach the groundwater. 6) Runoff: Runoff water is the water that doesn’t get soaked up by the soil and instead runs off the surface and flows downhill to reach lakes, rivers, ponds, streams or the ocean! We are all made from dinosaur spit! Since the water on Earth hasn’t changed since it formed 5 billion years ago and all living things are mostly made of water, there is a very high probability that at one time, the water that makes up you would have been in a dinosaur! Reading Comprehension Questions: 1) What is the water cycle? 2) Why does the amount of water on earth never change? 3) What are the three states that water can be in? Extension Questions 4) Draw a diagram of the water cycle with all the processes listed in the article. Your drawing must be different from the one provided and must show creativity and use color for full marks. 5) Research how climate change can affect the water cycle. Summarize your findings in 2-3 paragraphs. 6) Research the negative impacts of runoff on the environment. Reading Comprehension Questions: Answer Key 1) What is the water cycle? The water cycle is the movement of water from land to water to the atmosphere and back again. 2) Why does the amount of water on Earth never change? The amount of water on Earth never changes because the Earth is a closed system. Matter never leaves the Earth’s system, it only changes from one state to another. 3) What are the three states that water can be in? Solid, liquid, gas. Extension Questions 4) Draw a diagram of the water cycle with all the processes listed in the article. Your drawing must be different from the one provided and must show creativity and use color for full marks. 5) Research how climate change can affect the water cycle. Summarize your findings in 2-3 paragraphs. 6) Research the negative impacts of runoff on the environment. References Kidzone Science (2016). The Water Cycle. Retrieved March 07, 2016, from http://www.kidzone.ws/water/ Science kids (2016). The Water Cycle. Retrieved March 07, 2016, from http://www.sciencekids.co.nz/sciencefacts/weather/thewatercycle.html USGS (2015, August). The Water Cycle, Retrieved March 07, 2016, from http://water.usgs.gov/edu/watercycle.html USGS (2015, August). Summary of The Water Cycle, Retrieved March 07, 2016, from http://water.usgs.gov/edu/watercyclesummary.html
