How The Earth Works
Earth: Basic Facts
• 150 million km from Sun (93 million miles)
• Diameter, just under 13,000 km (8,000 mi.)
• Density: 5.5 g/cc (5500 kg/m3)
– About twice as dense as surface rocks
– Earth has a dense core
• Unique Features
– Liquid Surface
– Plate Tectonics
– Life
Earth Systems
Earth Systems
Earth Systems
Earth Systems
Earth Systems
Earth Systems
Earth Systems
Earth Systems
The Solid Earth
Earth Systems
•
•
•
•
•
•
External Effects (Astronomical)
Atmospheric Circulation
Oceanic Circulation
Hydrologic Cycle
Rock Cycle
Plate Tectonics
Convection
Earth and the Universe
•
•
•
•
•
•
Rotation (Day-Night)
Lunar (Tides)
Annual (Seasons)
Precession and Orbit Variations (Ice Ages?)
Galactic (250 m.y. period)
Unpredictable Events
– Nearby Supernovae
– Meteor Impacts
• Long-Term Evolution of Sun
The Atmosphere
• 79% Nitrogen, 20% Oxygen, 1% Argon
• Oxygen made by life
– Example: glucose C6H12O6
– 6H2O + 6CO2  C6H12O6 + 6O2
• Greenhouse effect
– Infrared absorbed by molecular vibrations
– 90% of earth’s greenhouse effect due to water
vapor
– Without a greenhouse effect, earth would be
frozen
Atmospheric Circulation
• Unequal Solar Heating
– Equator to Pole
– Day - Night
– Different Surfaces
• Buoyancy
• Adiabatic Heating and Cooling
• Coriolis Effect
• High and Low Pressure
• Fronts and Air Masses
Not a
Manifestation of
the Coriolis
Effect!
• Too small scale
for the Coriolis
Effect to be
significant
Atmospheric Circulation
Oceanic Circulation
• Surface Currents - Driven by Winds
• Thermohaline - Deep Circulation
– Evaporation makes water more saline and
denser
– Freezing makes water more saline and denser
– Cold water is denser than warm water
Surface Currents
Thermohaline Circulation
Hydrologic Cycle
• Evaporation from Oceans
• Precipitation on Land
– Infiltration into Ground (Ground Water)
– Runoff (Erosion)
Hydrologic Cycle
Water
• Principal Agent in Modifying Earth’s Surface
• Medium for Storing and Distributing Global
Heat
• The Universal Solvent
– Essential for Life
– Destructive to Rocks
• Lowers Melting Point of Rocks
• Reduces Strength of Rocks Under Pressure
The Rock Cycle
• New Rocks Exposed by Erosion
• Rocks Broken Down Mechanically and Chemically
(Weathering)
• Components Transported by Erosion
• Components Cemented into Sedimentary Rocks
• Burial and Heating creates Metamorphic Rocks
• Melting Creates Igneous Rocks
The Rock Cycle
Plate Tectonics
• Outer Crust of Earth Moves a Few cm/yr
• Driven by Convection in Earth’s Interior
• Accounts For:
– Earthquakes
– Volcanoes
– Mountain-Building (Orogeny)
• Configuration of Continents
Convection In The Earth
Convection In The Earth
Plate Tectonics
Plate Tectonics
The Carbonate-Silicate Cycle
Configuration of Continents
• Oceanic Circulation
• Weather and Climate Patterns
– Deserts
– Mountains and Rain Shadows
• Pathways for Migration
• Ecological Niches
Configuration of Continents