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Earth as a SystemCh. 1
What is the Earth system,and where do we humans fit in?
A New View of Earth• What do earth
scientists study?– solid earth, oceans,
oceans, space• In past studied
separate parts– How has this
changed? Why?» now often studied
as a system• b/c realized
parts are connected and interact
A New View of Earth• What sparked this
new view of Earth as system?– space exploration
• “blue marble” photo (Apollo 17)
– satellite imaging– environmental
incidents– deep sea
exploration– computers &
Geographic Information Systems (GIS)
Models & Systems• What is a model?– a simplified representation of an object, process, or
phenomenon– a way to predict if-then scenarios (for the past & future)
• What happens when scientists learn more about the world?– Models can be modified or replaced with a new model
• What is a system?– group of objects or phenomena that
share matter & energy• Ex. Earth’s spheres
– A type of model
Open & Closed Systems• What is an open system?– a system & its surroundings that exchange energy & matter
• How is a closed system different from an open system?– energy can be exchanged… matter CAN’T be exchanged
• Is Earth an open system or a closed system? Why?– technically, open, but usually considered closed b/c exchange
of matter is extremely small
Earth’s Spheres
Examples of how the spheres interact & changes that result…
Overall, Earth is in balance…• Changes to one sphere can have impacts on one or
more or the others– human activities have major impacts on the spheres
• However, overall, Earth is in balance. How?– biogeochemical cycles• carbon cycle• water cycle• rock cycle• … and more
Nitrogen Cycle
SedimentsErosion
Weathering
Deposition
Igneous rock Granite, pumice, basalt
Sedimentary rock sandstone, limestone
Heat, pressure
Cooling & solidification
Heat, pressure (metamorphism)
Magma(molten rock)
Melting
Metamorphic rock slate, marble, gneiss, quartzite
Rock Cycle
The Energy Budget• “energy budget” is
sometimes called “energy cycle” or “energy balance”– amount of energy
that enters should equal amount that exits• What happens if
more energy enters?– heating
• What happens if more energy enters?– cooling
The Energy Budget & the Laws of Thermodynamics
• Can energy be created or destroyed?– No, it can only be transferred & transformed (1st Law)
• Can energy ever be recycled completely?– No, when energy changes it is degraded into a less useful
form & “lost” (in terms of its original form) (2nd law)• “Lost” energy is usually given off as…?
– heat
Chemicalenergy(food)
Solarenergy
WasteHeat
WasteHeat
WasteHeat
WasteHeat
Mechanicalenergy
(moving,thinking,
living)
Chemical energy
(photosynthesis)
Earth’s Surface & the Energy Cycle• How can Earth’s
surface affect the energy budget?– “albedo” is the ability
of a surface to reflect light• What type of surfaces
would have a low “albedo”?– dark & dull
• What type of surfaces would have a high “albedo”?– light & shiny
– changes in surface type change the energy budget
Factors Affecting Rates of Temperature Change Visualization
