Water Cycle

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Water Cycle
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The Water Cycle
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The Water Cycle

• Terminology
• Evaporation
• Sublimation
• Transpiration
• Condensation
• Precipitation
• Infiltration

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Water storage in oceans

• 97 of Earths water is in the oceans
• Currents move water around the world

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EVAPORATION

• Process by which liquid water changes to water
  vapor (gas)
• Oceans, seas, lakes and rivers provide 90 of
  moisture in our atmosphere via evaporation
• Heat (energy) is necessary
• Drives the water cycle

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SUBLIMATION

• Snow and ice change into water vapor without
  first turning to liquid
• Common way for snow to disappear
• Hard to see happening
• Occurs when there is low relative humidity and
  dry winds
• Solar energy is needed

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TRANSPIRATION

• The release of water from plant leaves
• Moisture leaves plants through holes in leaves
  called stomata
• Invisible
• Atmospheric factors affect transpiration
• Temperature
• Relative humidity
• Wind movement
• Soil-moisture availability

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CONDENSATION

• Process by which water vapor is changed into
  liquid water
• Responsible for the formation of clouds

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PRECIPITATION

• Water released from clouds in the form of rain,
  snow, etc
• Water droplets in clouds collide. If enough
  collisions occur to produce a droplet with a fall
  velocity greater the the cloud updraft speed,
  then it will fall out of the cloud as
  precipitation

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SURFACE RUNOFF

• Precipitation runoff travels over the soil
  surface to the nearest stream channel
• Not simply into rivers then oceans, because
  rivers gain and lose water to the ground

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Ground Water

• Mostly confined to permeable rocks called
  aquifers
• Surface deposits
• Porous rocks sandstone
• Fractured rocks limestone
• Underground Streams are rare, short, and small.

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Ground Water
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Aquifers
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Aquifers

• Water gets in from the surface at the recharge
  zone
• Boundary of water-saturated rocks is the water
  table or piezometric surface
• The upper surface of ground water
• Water pressure is equal to atmospheric pressure
• Intersects surface at springs, swamps and ponds
• Below that all pore spaces and cracks are
  completely filled (saturated) with water

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Misuse of Ground Water

• Contamination of Recharge Zone
• Excessive Drawdown
• Can dry out nearby wells or springs
• Can suck in salt or contaminated water
• Can cause land subsidence