freshwater
TRANSCRIPT
Earth’s Water
How is water distributed on Earth?• remains fairly constant• 97% is saltwater –
unusable• most freshwater (69%) is
ice – polar ice caps, glaciers, etc.
• 30% of freshwater is groundwater
• .3% (of the 3%... that is .09% of all water) is surface water
• You are drinking water that dinosaurs could have swam in, drank, etc.
What is the hydrologic cycle?• the movement and storage of water in the
hydrosphere• http://www.epa.gov/safewater/kids/flash/flas
h_watercycle.html
How does water move through the cycle?
• Evaporation (includes transpiration)
• Condensation• Precipitation• Collection/
storage
How does water evaporate?1. Solar energy adds heat
energy.2. Water molecules absorb
heat energy.3. Heat energy speeds up the
molecules. 4. Water changes from a
liquid state into a gas state (vapor).
sweat
transpiration
What causes condensation?
1. Water vapor releases heat energy.
2. Water vapor molecules change from a gas state to a liquid state.
What causes precipitation?
Gravity!
How is water collected?
Surface Water• river systems
(watersheds)• oceans• runoff
Groundwater• infiltration/percolation• aquifers• can discharge to surface
water
What is groundwater?
permeable –allows water to pass through
pores in zone of aeration
water table – must drill below for water
Impermeable - bedrock