What are the different forms of water as they exist on Earth?
How many planets in our solar system have liquid water on their surface?
How many atoms form one water molecule?
Earth's Water Supply
The vast majority of earth's water supply is contained in the oceans as saltwater.
The vast majority of earth's freshwater supply is stored in icebergs and glaciers .
The largest source of liquid freshwater is groundwater .
Water Cycle Overview
Water converted from liquid to gas (water vapor)
Surface water (lakes, rivers, & mostly oceans)
Sun provides energy needed to change state
Emission of water vapor from plants
Plants absorb water from soil to use in photosynthesis
Water vapor released through stomata (pores) under leaves
Water vapor (gas) turns into liquid water
Warm, moist air rises in atmosphere
Vapor in air cools as it rises, thus turning back to liquid
Water falling from the atmosphere
Vapor molecules collide & join to form droplets
Falls as rain, snow, sleet, or hail
Water absorbed into subsurface of dirt & rocks
Water percolates down between spaces in soil
Groundwater empties into streams/rivers/oceans or is stored underground in aquifers
Saturation = all the spaces in soil & rock are filled with water
when soil becomes saturated, or
when precipitation falls faster than infiltration can occur
Precipitation seeps down through soil & rock
Layers act as filters that trap contaminants
Water table: imaginary line between the water-logged soil and the soil not saturated with water
varies with seasonal precipitation, pumping, & geography
Two types of aquifers :
unconfined : water supply which has a solid layer of rock under it, but a permeable layer of rocks above it
confined : water supply sandwiched between two solid rock layers through which water cannot pass
pressure builds up and can form an artesian well
Water flows over the ground instead of sinking into the ground
Snow melts, rain runs off surfaces, etc.
Streams and rivers carry water back to oceans
The average time a given molecule of water will stay in a given water source
1 - 10 years Swamps 2 weeks Rivers 10 years Lakes 10 days Atmosphere 2 weeks - 1 year Soil 2 weeks - 1000 years Groundwater Up to 1000 years Glacier/Iceberg Up to 4,000 years Ocean Residence Time Water Source