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Lesson 2 Water Cycle (The Hydrologic Cycle)

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Lesson 2 Water Cycle (The Hydrologic Cycle) Lesson 2 Water Cycle (The Hydrologic Cycle) Overview: Two investigations introduce students to the hydrological cycle Disciplinary Core Ideas (water cycle). An understanding of the basic water cycle is the base for knowing that the Columbia River and its watershed is Science part of an earth system that continually renews itself. 4PS3-2 Make observations to Investigation 2.1 students create a simple model of the water provide evidence that energy cycle and identify the primary locations where water can be transferred from place condenses, evaporates and precipitates. Through class to place by sound, light, heat, discussion they will identify the state of matter as water and electric currents. moves through the cycle. Investigation 2.2 students will explore the water cycle in Social Studies more depth as they travel through the in and around earth as Geography 3.1.2 a molecule of water. They will collect a record of their travels to be discussed as a class and recorded at the end of the Understands the physical, activity. political, and cultural characteristics of places, Student Learning Targets regions, and people in the Pacific Northwest… I can explain the Water Cycle in words, phrases, pictures, or Scientific and Engineering diagrams. Practices I can explain the energy transfers between solid, liquid and Developing and using models gas forms of water in words, phrases, pictures, or diagrams. Crosscutting Concepts I can sketch and label the Washington State Water cycle in Energy and matter: Flows, words and pictures or diagrams. cycles, and conservation River of Power – North Central ESD 2013 rev. Lesson 2 - Page 1 Teacher Background Information States of Matter – states of water “Water is made of molecules; each water molecule contains two hydrogen atoms and one atom of oxygen. Molecules constantly move. Academic Vocabulary Heat energy contributes to the motion of molecules Energy transfer: The movement of (kinetic energy). When water feels warm, molecules are energy from one location to another. moving very rapidly. Water molecules with little heat energy, such as those in an ice cube, move more slowly. Condensation: The change of the The motion of molecules determines the state of water. In physical state of matter from a gas the gaseous state (water vapor), water molecules have a to a liquid. large amount of heat energy and move rapidly. This rapid movement causes molecules to bounce off each other, Evaporation: The change in state of resulting in greater distances between the molecules. a substance from liquid to gas. (Compare the amount of space needed by a person who is moving around rapidly to someone who is standing still.) Precipitation: Any product of the The molecules in liquid water move more slowly. The condensation of atmospheric water molecules require less space and are closer to each other. vapor deposited on Earth's surface, In ice, the molecules contain the least amount of heat such as rain, snow, or hail. energy, so their movement is very slow. (Water molecules in ice form a lattice pattern. Gas: A state of matter consisting of a Water changes from one state to another when heat collection of particles energy is added or lost. Heat travels from areas of high without a definite shape or volume temperature (rapidly moving molecules) to low that are in more or less random temperature (slower-moving molecules). motion. Ice melts in your hand because the heat from your body Solid: Retains its shape when not transfers to the colder material. Sometimes, when Confined. molecules near the surface of liquid water move very rapidly, they break away or evaporate, becoming water Liquid: A fluid that takes the shape vapor. Eventually water vapor will lose energy and return of the part of the container that it to liquid form. This can be seen when steam condenses on occupies, and that forms a distinct a cool bathroom mirror. Water will also change from a surface. liquid to a solid as heat energy continues to be lost. However, even as ice, water molecules contain some heat energy. Therefore, although the movement is limited, the molecules are still in motion.” “Project Wet” Water Cycle “What is the water cycle? The water cycle describes the existence and movement of water on, in, and above the Earth. Earth's water is always in movement and is always changing states, from liquid to vapor to ice and back again. The water cycle has been working for billions of years and all life on Earth depends on it continuing to work; the Earth would be a pretty stale place to live without it. Where does all the Earth’s water come from? Primordial Earth was an incandescent globe made of magma, but all magmas contain water. Water set free by magma began to cool down the Earth’s atmosphere, until it could stay on the surface as a liquid. Volcanic activity kept and still keeps introducing water in the atmosphere, thus increasing the surface- and ground-water volume of the Earth.” River of Power – North Central ESD 2013 rev. Lesson 2 - Page 2 Resource: http://ga.water.usgs.gov/edu/watercyclesummary.html “The water cycle, also known as the hydrological cycle or H2O Disciplinary Core Ideas cycle, describes the continuous movement of water on, above and below the surface of the Earth. Although the balance of water on Science Earth remains fairly constant over time, individual water molecules 4PS3-2 Make observations to can come and go, in and out of the atmosphere. The water moves provide evidence that energy from one reservoir to another, such as from river to ocean, or from can be transferred from place the ocean to the atmosphere, by the physical processes of to place by sound, light, heat, evaporation, condensation, precipitation, infiltration, runoff, and and electric currents. subsurface flow. In so doing, the water goes through different phases: liquid, solid (ice), and gas (vapor). Social Studies Geography 3.1.2 The water cycle involves the transfer of heat, which leads to Understands the physical, temperature changes. For instance, when water evaporates, it political, and cultural takes up energy from its surroundings and cools the characteristics of places, environment. When it condenses, it releases energy and warms regions, and people in the the environment. These heat transfers influence climate. (4-PS3- Pacific Northwest… 2) By transferring water from one reservoir to another, the water cycle purifies water, replenishes the land with freshwater, and Scientific and Engineering transports minerals to different parts of the globe. It is also involved Practices in reshaping the geological features of the Earth, through such Developing and using models processes as erosion and sedimentation. Finally, the water cycle figures significantly in the maintenance of life and ecosystems on Crosscutting Concepts Earth. Energy and matter: Flows, cycles, and conservation Description The Sun, which drives the water cycle, heats water in oceans and seas. Water evaporates as water vapor into the air. Ice and snow can sublimate directly into water vapor. Evapotranspiration is water transpired from plants and evaporated from the soil. Rising air currents take the vapor up into the atmosphere where cooler temperatures cause it to condense into clouds. Air currents move water vapor around the globe, cloud particles collide, grow, and fall out of the upper atmospheric layers as precipitation. Some precipitation falls as snow or hail, sleet, and can accumulate as ice caps and glaciers, which can store frozen water for thousands of years. Most water falls back into the oceans or onto land as rain, where the water flows over the ground as surface runoff. A portion of runoff enters rivers in valleys in the landscape, with streamflow moving water towards the oceans. Runoff and groundwater are stored as freshwater in lakes. Not all runoff flows into rivers, much of it soaks into the ground as infiltration. Some water infiltrates deep into the ground and replenishes aquifers, which store freshwater for long periods of time. Some infiltration stays close to the land surface and can seep back into surface-water bodies (and the ocean) as groundwater discharge. Some groundwater finds openings in the land surface and comes out as freshwater springs. Over time, the water returns to the ocean, where our water cycle started. River of Power – North Central ESD 2013 rev. Lesson 2 - Page 3 Processes Preciptation Condensed water vapor that falls to the Earth's surface . Most precipitation occurs as rain, but also includes snow, hail, fog drip, graupel, and sleet.[1] Approximately 505,000 km3 (121,000 cu mi) of water falls as precipitation each year, 398,000 km3 (95,000 cu mi) of it over the oceans.[2] Canopy interception The precipitation that is intercepted by plant foliage, eventually evaporates back to the atmosphere rather than falling to the ground. Snowmelt The runoff produced by melting snow. Runoff The variety of ways by which water moves across the land. This includes both surface runoff and channel runoff. As it flows, the water may seep into the ground, evaporate into the air, become stored in lakes or reservoirs, or be extracted for agricultural or other human uses. Infiltration The flow of water from the ground surface into the ground. Once infiltrated, the water becomes soil moisture or groundwater.[3] Subsurface flow The flow of water underground, in the vadose zone and aquifers. Subsurface water may return to the surface (e.g. as a spring or by being pumped) or eventually seep into the oceans. Water returns to the land surface at lower elevation than where it infiltrated, under the force of gravity or gravity induced pressures. Groundwater tends to move slowly, and is replenished slowly, so it can remain in aquifers for thousands of years.
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