Draw The Water Cycle WORK
Water cycle components Atmosphere Condensation Evaporation Evapotranspiration Freshwater lakes and rivers Groundwater flow Groundwater storage Ice and snow Infiltration Oceans Precipitation Snowmelt Springs Streamflow Sublimation Surface runoff
draw the water cycle
Plant transpiration is pretty much an invisible process. Since the water is evaporating from the leaf surfaces, you don't just go out and see the leaves "breathing". Just because you can't see the water doesn't mean it is not being put into the air, though. One way to visualize transpiration is to put a plastic bag around some plant leaves. As this picture shows, transpired water will condense on the inside of the bag (this photo shows transpiration after 1 hour). During a growing season, a leaf will transpire many times more water than its own weight. An acre of corn gives off about 3,000-4,000 gallons (11,400-15,100 liters) of water each day, and a large oak tree can transpire 40,000 gallons (151,000 liters) per year.
Plants put down roots into the soil to draw up water and nutrients into its stems and leaves. Some of this water is returned to the air by transpiration. Transpiration rates vary widely depending on weather and other conditions, such as
Type of plant: Plants transpire water at different rates. Some plants which grow in arid regions, such as cacti and succulents, conserve precious water by transpiring less water than other plants.
Soil type and saturation: Clay particles are small (smaller than 0.002 mm), holding onto water whereas sand particles which are large (0.05-2 mm) release water readily (think of how water disappears into the sand quickly at the beach). When moisture is lacking, plants can begin to senesce (premature aging, which can result in leaf loss) and transpire less water.
Humidity: As the relative humidity of the air surrounding the plant rises the transpiration rate falls. It is easier for water to evaporate into dryer air than into more saturated air.
Temperature: Transpiration rates go up as the temperature goes up, especially during the growing season, when the air is warmer due to stronger sunlight and warmer air masses. Higher temperatures cause the plant cells which control the openings (stoma) where water is released to the atmosphere to open, whereas colder temperatures cause the openings to close.
In many places, plant roots are found in the top layer of soil, above the water table. The top layer of soil is often wet to some extent, but is not totally saturated. Soil below the water table is very wet.
The top layer of soil gets wet when it rains (a form of precipitation), but if there is no more precipitation, the soil will dry out. Therefore, the plants are dependent on water supplied by precipitation since the water table is usually below the depth of the plant roots.
The water cycle shows the continuous movement of water within the Earth and atmosphere. It is a complex system that includes many different processes. Liquid water evaporates into water vapor, condenses to form clouds, and precipitates back to earth in the form of rain and snow. Water in different phases moves through the atmosphere (transportation). Liquid water flows across land (runoff), into the ground (infiltration and percolation), and through the ground (groundwater). Groundwater moves into plants (plant uptake) and evaporates from plants into the atmosphere (transpiration). Solid ice and snow can turn directly into gas (sublimation). The opposite can also take place when water vapor becomes solid (deposition).
Humans use water for drinking, industrial applications, irrigating agriculture, hydropower, waste disposal, and recreation. It is important that water sources are protected both for human uses and ecosystem health. In many areas, water supplies are being depleted because of population growth, pollution, and development. These stresses have been made worse by climate variations and changes that affect the hydrologic cycle.
The water cycle impacts ecosystems, economies, and our daily lives. The resources in this collection help teachers guide their students beyond the classic water cycle diagram and through the complex social and environmental issues that surround water. The water cycle provides the opportunity to explore the nature of science using models and empirical evidence.
Discuss what happens to rain and snow on Earth. Most falls back into the ocean. Some falls into rivers that flow into the ocean. Some falls on land, sinks into the ground, and drains slowly back into the ocean. It may take thousands of years, but eventually all water returns to the ocean. Have students draw a river emptying into the ocean and water sinking underground and draining into the ocean. Tell students their illustration of the water cycle is now complete. Project the USGS water cycle diagram and have the class compare the two and add additional details to their illustration, if needed.
6. Discuss students' stories and the importance of oceans.Invite volunteers to share some of the adventures they wrote about in their stories. Ask: Why are oceans important? Discuss how they are not only the source of most of the water we use, but also a place where many animals live. If we want to keep our planet healthy, we must take good care of the oceans.
Conduct a simple science experiment so students can see firsthand how water evaporates, condenses, and precipitates. Fill a plastic cup halfway with water, place it inside a re-sealable plastic bag, close the bag, and set it on a sunny windowsill. Ask students to imagine that the water in the cup is the ocean, and have them check it daily to observe what happens. As students make observations, connect their observations to the processes of evaporation, condensation, and precipitation. Explain to students that each day the water level gets lower as water evaporates. The top of the bag gets cloudy as water condenses. And eventually water drops appear on the side of the bag and at the bottom as the water precipitates.
Water vapor surrounds us, as an important part of the air we breathe. Water vapor is also an important greenhouse gas. Greenhouse gases such as water vapor and carbon dioxide insulate the Earth and keep the planet warm enough to maintain life as we know it. Increasing amounts of greenhouse gases in the atmosphere also contribute to global warming.
The water cycle's evaporation process is driven by the sun. As the sun interacts with liquid water on the surface of the ocean, the water becomes an invisible gas (water vapor). Evaporation is also influenced by wind, temperature, and the density of the body of water.