Transcript Water
Water Science 7 • Of all the water on Earth, 97% is in the ocean and only 3% is fresh water –2% is frozen –less than 1% for drinking water The Three Forms of Water. • Solids: When water becomes very cold and freezes it will change from a liquid to a solid. It has a definite form and shape. • Ice, frost, glacier The Three Forms of Water. • Liquids: When water takes the shape of its container it is in a liquid form. • Lake, river, rain The Three Forms of Water. • Gases: When water is seen in a vapor form and has no definite size or shape it is in a gas form. Geyser, clouds, fog Precipitation • the process in which water (in the form of rain, snow, sleet, or hail) falls from clouds in the sky. Surface Runoff • - rain, snow melt, or other water that flows in surface streams, rivers, or canals. • A watershed is the region of land from which surface runoff drains into various bodies of water. • Recharge Zone - The area of land, and permeable features, that allows water to replenish an aquifer (porous, watersaturated layer of earth materials through which water flows). This process occurs naturally when rainfall filters down through the soil or rock into an aquifer. Subsurface Runoff • - rain, snow melt, or other water that flows in underground streams, drains, or sewers. • Groundwater – results from precipitation that infiltrates the ground & seeps downward through fractures, pores & other spaces in soil & rock. Infiltration rate depends on porosity (percentage of void space in a rock), type, texture & structure of the soil & moisture content (Permeability) • Percolation – Movement of water through the soil by gravity & capillary forces Subsurface Runoff • Zone of aeration (unsaturated zone) – layer of earth in which rock & soil may be moist, but are not saturated with water; full of air (vadose water) • Water table – Line between unsaturated & saturated zones – will vary due to rainfall amounts, runoff & infiltration. (During wet weather, water table is closer to surface; during dry weather, it falls away from surface) • Zone of saturation – layer of soil above bedrock that is completely filled with water Accumulation • the process in which water pools in large bodies (like oceans, seas and lakes). • Discharge area – outlets - areas where water accumulates – geysers, streams, oceans. Evaporation • the process in which liquid water becomes water vapor (a gas). Water vaporizes from the surfaces of oceans and lakes, from the surface of the land, and from melts in snow fields. • Transpiration - the process in which some water within plants evaporates into the atmosphere. Water is first absorbed by the plant's roots, then later exits by evaporating through pores in the plant. Condensation • the process in which water vapor (a gas) in the air turns into liquid water. Condensing water forms clouds in the sky. Water drops that form on the outside of a glass of icy water are condensed water. (This term appears twice in the diagram.) Water Pollution Turgor Pressure • Turgor Pressure: also called turgidity, is the main pressure of the cell contents against the cell wall in plant cells. Turgid plant cells contain more water than flaccid cells and exert a greater osmotic pressure on its cell walls. • Turgor is a force exerted outward on a plant cell wall by the water contained in the cell. This force gives the plant rigidity, and may help to keep it erect. Turgor can result in the bursting of a cell.