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St. Michael School Scout Group

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1 St. Michael School Scout Group
The Water Cycle Hello. This is our title page. Therese Camilleri St. Michael School Scout Group

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Therese Camilleri VSL St. Michael School Scout Group

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Therese Camilleri VSL St. Michael School Scout Group

4 The Role of Water for Living Organisms
Without water, the other nutrient cycles would not exist in their present forms and current forms on earth would not exist. Water determines the type of organisms in terrestrial systems. Therese Camilleri VSL St. Michael School Scout Group

5 The Role of Water for Living Organisms
The flow of water in an out of an aquatic ecosystem affects physical conditions for organisms by influencing temperature, salinity, and availability of nutrients. Therese Camilleri VSL St. Michael School Scout Group

6 How the Water is Cycled in the Ecosphere
Main process of the water cycle Evaporation Transpiration Condensation Precipitation Infiltration Percolation Runoff Therese Camilleri VSL St. Michael School Scout Group

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Evaporation Conversion of water into air vapor Therese Camilleri VSL St. Michael School Scout Group

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Evaporation Cont Water cycle is powered by energy from the sun and gravity. Solar energy evaporates water from oceans, streams, lakes, soil, and vegetation. Therese Camilleri VSL St. Michael School Scout Group

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Evaporation Cont Percent of water vapor in atm. includes 84% from oceans 16% from land Amount of water vapor entering the atmosphere is amount of water returning to earths surface. Therese Camilleri VSL St. Michael School Scout Group

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Transpiration Evaporate from leaves of water, extracted from soil by roots, and transported through the plant. Therese Camilleri VSL St. Michael School Scout Group

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Condensation Conversion of water vapor into droplets of liquid water. Therese Camilleri VSL St. Michael School Scout Group

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Precipitation Rain, sleet, hail, and snow. Therese Camilleri VSL St. Michael School Scout Group

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Water Vapor Amount of water vapor air can hold depends on temperature. Warm air is capable of holding more water vapor than cold air. Therese Camilleri VSL St. Michael School Scout Group

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Humidity Absolute Humidity Amount of water vapor found in a certain mass of air. Usually expressed as grams of water per kilogram of air. Therese Camilleri VSL St. Michael School Scout Group

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Humidity Cont Relative Humidity The amount of water vapor in a certain mass of air. Expressed as a percentage of the maximum amount it could hold at that temperature. Therese Camilleri VSL St. Michael School Scout Group

16 Example of Relative Humidity
Example: Relative humidity of 60% at 27 degrees Celsius means that each kg of air contains 60% of the maximum amount of water vapor it could hold at that temperature. Therese Camilleri VSL St. Michael School Scout Group

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Infiltration The movement of water into soil Therese Camilleri VSL St. Michael School Scout Group

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Percolation Downward flow of water through soil and permeable rock formations to groundwater storage areas called aquifers. Therese Camilleri VSL St. Michael School Scout Group

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Runoff Downslope surface movement back to the sea to resume the cycle. Therese Camilleri VSL St. Michael School Scout Group

20 Water Vapor to Precipitation
Winds and air masses transport water vapor over earth’s surfaces. This water vapor condenses into tiny droplets that form clouds as a result of falling temperatures. Therese Camilleri VSL St. Michael School Scout Group

21 Water Vapor to Precipitation Cont
Precipitation will then occur only if the air has condensation For condensation to occur the temperature must be at dew point. Therese Camilleri VSL St. Michael School Scout Group

22 Precipitation to Runoff
77% of precipitation falls to the sea, the rest falls to land. Some of the precipitation becomes locked in glaciers Therese Camilleri VSL St. Michael School Scout Group

23 Precipitation to Runoff cont
Most of the precipitation becomes surface runoff flowing into streams and lakes which eventually carry water back to the oceans where it starts all over again. Therese Camilleri VSL St. Michael School Scout Group

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Surface Runoff Replenishes streams and lakes. Causes soil erosion. Water dissolves many nutrient compounds which makes it a major medium for transporting nutrients. Therese Camilleri VSL St. Michael School Scout Group

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Percolation Some of the water returning to the land soaks into (infiltrates) the soil and porous rock and then percolates downward, dissolving minerals from porous rocks on the way. This water is stored as groundwater in the pores and cracks of rocks. Therese Camilleri VSL St. Michael School Scout Group

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Percolation Cont Where the pores are joined, a network of water to flow through the porous rock. Aquifer: water-laden rock Water table: level of the earth’s land crust to which it is filled. Therese Camilleri VSL St. Michael School Scout Group

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Percolation Cont This underground water flows slowly downhill through rock pores and seeps out into streams and lakes or comes out in springs.      This water evaporates or reaches the sea to continue the cycle. Therese Camilleri VSL St. Michael School Scout Group

28 Humans Influence the Water Cycle
Humans intervene in the water cycle in three main ways: We withdraw large quantities of fresh water. We clear vegetation from land. We modify water quality Therese Camilleri VSL St. Michael School Scout Group

29 Humans Influence the Water Cycle cont
We withdraw large quantities of fresh water from streams, lakes, and underground sources. This has led to depletion or intrusion of ocean salt water into underground water supplies Therese Camilleri VSL St. Michael School Scout Group

30 Humans Influence the Water Cycle cont
We clear vegetation from land for agriculture, mining, road and building construction and other activities. This increases runoff and reduces infiltration that recharges groundwater supplies. Increases the risk of flooding and accelerates soil erosion and landslides. Therese Camilleri VSL St. Michael School Scout Group

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Bibliography  http://www.enchantedlearning.com/subjects/astronomy/planets/earth/Watercycle.shtml  http://www.sensorland.com/HowPage037.html  http://www.ph-measurement.co.uk/home.htm  http://sjr.state.fl.us/programs/outreach/conservation/landscape/images/phbarp6.jpg  http://old.jccc.net/~pdecell/chemistry/phscale.html  http://www.epa.gov/airmarkets/acidrain/ph.html  http://www.css.cornell.edu/faculty/hmv1/watrshed/CDIB354.gif  http://www.nwd-wc.usace.army.mil/nwp/gifs/pics/transpiration.gif  http://www.dutchstandard.com/droplet.gif Miller, G. Tyler Jr. Living in the Environment. Pacific Grove; Brooks/Cole Publishing Company, 2000. Therese Camilleri VSL St. Michael School Scout Group


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