Week March 28 – April 1

1. Week March 28 – April 1

2. Monday, March 28 • Objective: SWU the importance of adequate quantities of quality water for meeting the needs of modern society. • Focus: What do you think are the major steps in wastewater treatment? • Activity: Where does the water in the water fountain come from? Is it clean? • Does the water in the toilet, water fountain, icemaker come from the same place? • How much water do you personally use? • Homework: Water diary ** On a sheet of paper, write down everything you use water for… estimate how much water you used each time. • This will be turned in for a grade on Thursday. • Be sure to date your diary, get a parent to initial it that they know what you were doing for homework. Parent notes are welcome.

3. Water Treatment Precipitation • In most parts of the United States, getting clean, safe water is as easy as turning on a faucet. Generally, this water comes from either groundwater or nearby streams and reservoirs. What most of us never see or have to worry about are the steps required to make this water drinkable. In this video segment adapted from ZOOM, cast member Noreen finds out how a water treatment facility in Cambridge, Massachusetts purifies its city's water.

4. Discussion Questions • Where does the water that enters your home come from? • Why is it important to treat water before sending it to homes? • What do you think the brown sludge is made of? What other things do you think are removed from water to make it safe for drinking? • Do you think all reservoirs prohibit swimming, fishing or boating? Why or why not? • Water is becoming more contaminated and scarce. What can (or do) you do to conserve water? List 5-10 different ways. • Link to the discussion page resource

5. Discussion QuestionsPrecipitation • What substance makes up rain, hail, and snow? • How are rain, hail, and snow alike? How are they different? • Have you experienced rain? Hail? Snow? How would you describe each form of precipitation to someone who had never experienced it? • What is the source of the water that makes rain, hail, and snow? • What happens to the water from rain, hail, or snow after the precipitation falls to the ground?

6. Background Essay • The water cycle — the continuous exchange of water between Earth's surface and atmosphere — is Earth's natural mechanism for recycling water. Liquid water on Earth's surface evaporates to become water vapor in the atmosphere; the water vapor produces clouds and precipitation; and the precipitation returns water to the surface. • Clouds are collections of billions of water droplets or ice crystals. When a mass of air is saturated with water and the temperature remains above 0°C (32°F), the water vapor condenses around particles in the air to form tiny droplets of water. If the temperature is below 0°C (32°F), water vapor is directly deposited as ice crystals. When the water droplets or ice crystals become too heavy to remain suspended in the atmosphere, they fall to Earth's surface as precipitation.

7. Background Essay continued • The two main forms of precipitation — rain and snow — can appear in many variations, including freezing rain, sleet, and hail. The type of precipitation that falls depends on the temperature of the air — both where the precipitation forms and through which it falls. When the air temperature is above 0°C (32°F), the precipitation falls as rain because the water stays in liquid form. When the air temperature is below 0°C (32°F), snow — crystalline flakes of frozen water — falls. Snowflakes take time to melt, so they can survive passing through a thin layer of air above 0°C (32°F), and snow can fall even when the air at ground level is warm. On the other hand, if rain — or snow that passed through a large enough warm layer that it melted — has to pass through a layer of freezing air near the ground, it may turn into sleet or freezing rain. Sleet is made up of drops of water that freeze near the ground, and freezing rain is made up of supercooled drops that freeze upon impact with surfaces below 0°C (32°F).

8. Background Essay continued • Hail — lumps of ice that can become as large as baseballs — forms in severe thunderstorm clouds that contain both rain and snow. As a snowflake falls through the cloud, water freezes around it and the pellet grows larger in size. Strong updrafts in the cloud then toss the frozen lump back up towards the top of the storm. As it falls through the cloud again, more layers of ice may be added. This may happen again and again, and it continues until the hailstone becomes too massive to be supported by the updraft and falls to the ground. • To learn more about the phases of water, check out Water Phases. • To learn more about the water cycle, check out Water Cycle Animation. • To learn more about clouds, check out Cloud Types.

9. Background Essay for Phases of water • As long as there has been water on Earth, it has participated in a continuous exchange between the surface and atmosphere. Water vapor in the atmosphere condenses to form clouds, which can produce precipitation. Rain, snow, and sleet return water from the atmosphere to Earth's surface. On the ground, the water cycle continues with infiltration (precipitated water seeps into the ground), runoff (water flows off the land into rivers, lakes, and oceans), and evapotranspiration (liquid water changes into vapor and is returned to the atmosphere by transpiration from plants and evaporation from surface water). • The phases of water depend on the motions of its molecules. When water exists in its liquid phase, the average kinetic energy of the water molecules is high enough for them to move freely around each other. This happens when temperatures range from 0°C to 100°C (32°F to 212°F). If the molecules do not have much energy of motion, such as when the temperature is below 0°C (32°F), their movement slows and they jiggle in place, creating the solid phase of water — ice. If the average kinetic energy of water molecules is very high, such as when the temperature is above 100°C (212°F), the molecules move very fast, bounce off each other, and spread out in the gaseous form — water vapor.

10. ContinuedBackground Essay for Phases of water • A molecule of water contains two hydrogen atoms and one oxygen atom. The way these atoms are joined together results in water molecules acting somewhat like miniature magnets. Water molecules have a positive side and a negative side and, as such, are strongly attracted to each other (hydrogen bonding). This attraction is what makes water molecules stick together to form droplets in clouds and helps water travel up through the roots of plants. • The Sun causes evaporation by heating liquid water on Earth's surface. Another process that releases water vapor into the atmosphere is transpiration — the evaporation of water from pores in the leaves of plants. Water vapor in the air is invisible — clouds and steam are actually millions of tiny droplets of liquid water or ice that form when the gaseous water molecules lose energy and condense around small particles in the air. As more water molecules collect on the cloud droplets, the drops get too heavy and fall from the cloud back to Earth's surface as precipitation. • To learn more about the water cycle, check out The Hydrologic Cycle and Biome in a Baggie. • To learn more about the phases of water, check out Water Phases. • To learn more about precipitation, check out Observe Precipitation.

11. Tuesday, March 29 Objective: SWU the importance of adequate quantities of quality water for meeting the needs of modern society. Focus: What is a reservoir? How much water do YOU use everyday? Activity: Water lab. Water, water everywhere. Homework: Water diary continued, due Thursday.

12. Wednesday, March 30 • Objective: SWU the importance of adequate quantities of quality water for meeting the needs of modern society. • Focus: Homework: How much water did you use? Discuss your diary in words in your spiral. • Did you discover places where you could conserve water? • Activity: • Global Water Distribution interactive • solar still • Homework: continue writing your water diary * • This will be turned in for a grade on Thursday. • Be sure to date your diary, get a parent to initial it that they know what you were doing for homework. Parent notes are welcome.

13. Background Essay • The continuous changes of state and movement of water throughout the Earth system -- the atmosphere, biosphere, lithosphere, and hydrosphere -- is known as the water cycle. The water cycle is driven by energy from the Sun, whose rays cause liquid water from Earth's surface to change into gas in a process called evaporation. As gaseous vapor rises and circulates in the atmosphere, it cools and changes back into a liquid, a process known as condensation. When water vapor condenses, tiny droplets form clouds, which return the water to Earth as precipitation. • Solar water distillation operates on the basic principles of the water cycle -- evaporation, condensation, and precipitation -- to purify water for drinking and other uses. The device used in distillation is called a still, which consists of a basin in which the source liquid is heated, a condenser in which the heated vapor is cooled back to the liquid state, and a collection vessel in which the purified liquid is collected.

14. Background Essay continued… • As demonstrated in this video segment, a basic solar still can be made using a large bowl, a cover that allows sunlight to easily penetrate to the source liquid in the bowl but prevents water vapor from escaping, and a collection cup no taller than the sides of the bowl. By placing a rock atop the plastic-wrap cover, droplets that form from the pure water vapor will run to the center of the cover. Provided the plastic wrap does not touch the rim of the collection cup, the purified water droplets will fall directly into the cup, leaving any contaminants or unwanted substances in the source liquid to settle in the bowl. • Solar stills have proven to be highly effective in cleaning up water supplies to provide safe drinking water, especially in remote areas or in emergency situations. In hurricane target areas like Florida, solar stills can provide an alternate source of clean water in the event of an extended power outage. • To learn more about evaporation, condensation, precipitation, and the other processes involved in the water cycle, check out Water Cycle Animation and The Hydrologic Cycle. • To learn more about how water changes state, check out Water Phases. • To learn more about the interconnected relationship between the atmosphere, biosphere, lithosphere, and hydrosphere, check out Earth as a System.

15. Solar Still Discussion Questions • Explain how this solar still works. • How do you think the salt water left in the big bowl compares to the original salt water? • What does this imply about what happens when water evaporates from the ocean? • If you couldn't taste the water you collected in a solar still, what test(s) could you perform to see if it contained any salt? • What is an example of the principles of the solar still at work on Earth's surface?

16. Thursday, March 31 • Objective: SWU the importance of adequate quantities of quality water for meeting the needs of modern society. • Focus: What is one change you can or did make that would help you conserve water? • Activity: • Global Rainfall • Homework: Turn in your water diary today. It must be turned in today for a grade. It is a daily grade.

17. Discussion QuestionsRainfall ** Global • What do the colors in this video represent? • Pick a time period, for example, two years, and view that part of the video again, observing the areas of greatest rainfall. Where and when do they occur? Do you see a pattern? Now look at another year or two. Is the pattern the same? • Why do you think there is more rainfall in some parts of the world than others? • Would you expect to see a relationship between the annual rainfall and the distribution of living things? Explain, giving specific examples.

18. Background Essay • Rain clouds can be formed by a number of different processes, including orographic ascent, convection, and convergence. Orographic ascent takes place when the shape of the landscape forces air upward; convection occurs when air at ground level is heated by Earth's surface, becomes less dense, and then rises up through the cooler, denser air above it; and convergence happens when two air masses meet, forcing one of them upward. • No matter what process causes air to rise, as it rises, it cools. When the temperature of the air falls below the dew point, the rate at which water vapor condenses onto tiny particles in the air to form cloud droplets exceeds the rate of evaporation of liquid water. As water vapor continues to condense onto the cloud droplets, the droplets grow in size until they are too heavy to remain suspended in the air, and they then fall to the ground as precipitation, namely rain or snow.

19. Background Essay continued • Looking at a map of global rainfall, it is easy to notice patterns in distribution. This video shows regional differences in rainfall as well as annual variations within regions. For example, rainfall is heaviest in the tropics — areas whose latitude is less than 23.5 degrees north or south of the equator and which receive a nearly constant amount of solar energy throughout the year. Because the warmer air is the more water vapor it can hold, the equatorial region, which receives the most solar radiation and is very warm, contains extremely moist air. In addition, the northern trade winds meet the southern trade winds in this region to create the Intertropical Convergence Zone (ITCZ) — a band around Earth where moist tropical air is forced upward and heavy rain showers and frequent thunderstorms are produced. During the course of a year, the ITCZ migrates with the most direct angle of sunlight. When it is summer in the northern hemisphere, the ITCZ shifts towards the north; when it is winter in the northern hemisphere, the ITCZ shifts toward the south.

20. Background Essay continued • Knowing the processes that form clouds and rain, it is possible to understand why trends exist in the global distribution of rainfall. In general, it is least likely to rain where the air is very stable and there is no mechanism to lift air masses, such as in flat desert areas. Central areas of continents that are far from sources of moisture produce little rain as well. Areas with colder climates, such as the polar regions, are also unlikely to produce precipitation because the air is simply too cold to hold much moisture. By contrast, areas that have mountain ranges near large bodies of water, such as the western coast of Canada, are likely to receive quite a lot of rain. • To learn more about the global distribution of water vapor, check out Water Vapor Circulation on Earth. • To learn more about the global weather system, check out Global Weather Machine. • To learn more about different climates, check out Observe Images of Different Climate Zones and Ocean Temperatures and Climate Patterns. • To learn more about the seasons, check out Earth in Motion: Seasons.

21. Friday, April 1 • Objective: SWU the importance of adequate quantities of quality water for meeting the needs of modern society. • Focus: What did you learn about water this week? At least three-four sentences. • Activity: Exam today over water (from the notes and videos and discussions this week)