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Exam 2. 2.5 pt improvement over 1 st exam (better than past) 150 (63%) improved over the first exam. Distribution of Earth’s Water. The Earth has 1.36 billion km 3 of water. The water occurs in one of three states: Liquid Solid Gas And is stored in one of the following major reservoirs
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Exam 2 • 2.5 pt improvement over 1st exam (better than past) • 150 (63%) improved over the first exam
Distribution of Earth’s Water The Earth has 1.36 billion km3 of water. The water occurs in one of three states: • Liquid • Solid • Gas And is stored in one of the following major reservoirs • Oceans • Atmosphere • Rivers/lakes • Groundwater • Glaciers
Changes of state and energy transfers Release of Energy • Gas to solid • Gas to liquid • Liquid to solid Requires Energy (storage) • Solid to gas • Solid to liquid • Liquid to Gas
Daily Question The hydrologic cycle describes the movement of water among the different reservoirs. Using the terms on the right (which represent both reservoirs and pathways) create a conceptual model that identifies that pathways that connect the reservoirs. • Ocean • Ground water • Atmosphere • Glaciers • Surface Water • Precipitation • Evaporation • Evapotranspiration • Infiltration • Ground water flow • Runoff
Hydrologic System • Hydrologic cycle – transfer of water between reservoirs. Solar energy drives the hydrologic cycle.
Evaporation – process by which water is transferred from the land and water masses of the earth to the atmosphere. • Transpiration – transfer of water from plants to the atmosphere, soil moisture taken up by vegetation is eventually evaporated as it exits plant pores. • Evapotranspiration – combination of evaporation and transpiration.
Conditions for Precipitation • Cooling of the air mass • Condensation – phase change from gas to liquid • Requires condensation nuclei: small particle of dust, previously formed ice or water drop, salt from ocean, clays, nitrogen oxides, etc. • Coalescence of water particles to form drops • Growth of drops until gravity is able to bring to Earth’s surface without evaporating first
Hydrologic Cycle • Precipitation – 4.2 trillion gallons per day • 66% is lost as evapotranspiration • 31% is runoff • 3% infiltrates into the subsurface
Infiltration and Ground water flow • Infiltration - the movement of water from the surface to subsurface • Could be from surface water reservoirs • Could follow rain event • Ground water flow is the movement of water in the subsurface • Can move back to surface water reservoir • Can move to the ocean
Runoff • The collective term describing the movement of water on the Earth’s surface, (primarily stream transport) • Factors affecting runoff • Geology - is it soil, unconsolidated material, or bedrock. Is it fractured? Is it porous? • Slope - a high angle of slope increases runoff • Vegetation covering - the more vegetation the less runoff • Time of the year - frozen ground vs. non-frozen ground, lower evapotranspiration vs. high evapotranspiration • Soil Saturation - if the soil is saturated there is no room for water to infiltrate • Type of precipitation - fast, hard rain increases runoff, slow soft rains allow for infiltration, snow vs. rain
Distribution of Evaporation & Precipitation More evaporation than precipitation occurs over the ocean More precipitation than evaporation occurs over land In the end, output from the ocean = input to the ocean and output from the land = input onto the land