environmental geography chapter 4

GEOG 106

Ch. 4: Global Cycles and Systemspp. 49-66

29 Sep and 1 Oct ‘09

What Makes Earth Unique?

• Intermediate distance from the Sun:– Approximately 150 million km (93 million mi),

• Average global surface temperature of 15˚C (60˚F):– Greenhouse effect of Earth’s atmosphere, and

• Water exists on Earth’s surface and atmosphere in three physical states:– Solid (ice), liquid, and gas (vapor).

Interactions among Earth’s Spheres:

• Atmosphere,• Biosphere,• Hydrosphere, and• Lithosphere.

• Lithosphere– Litho, Greek for “stone”

• Atmosphere– atmo, Greek for “air”

• Hydrosphere– hydro, Greek for “water”

• Biosphere– bio, Greek for “life”

L

A H

B

Interacting spheres

The Environmental Spheres

Interrelationships among Earth’s Spheres:

Fig 4.1: Locations and relative densities of Earth’s spheres.

Outgassing of the lithosphere into the atmosphere:

Fig. 4.2: Outgassing via volcanic activity. Volcanoes are concentrated along plate boundaries.

Earth’s Crust:

Earth’s Interior:

Rock Cycle:

Geologic Time:

Geologic Time:

Plate Tectonics:

• All forms of breaking and bending of the entire lithosphere, including the crust.

• Includes convergent, divergent, and transform interactions.

• Includes both folding and faulting.

Lithospheric Plates:

Lithospheric Plates:

Plate Boundary Interactions:

Plate Boundary Interactions:

Weathering, Mass Wasting, and Erosion:

Weathering:

Note that weathering increases surface area!

Physical Weathering:

• Ice/Frost Wedging,

• Salt Wedging,

• Wave action, and

• Root wedging.

Chemical Weathering:• Oxidation,• Carbonation,

• Hydration, and

• Solution.

Carlsbad Caverns, New Mexico

Mass Wasting:

• Creep (slow),• Solifluction (slow),• Slumping and Earthflows (fast),• Rock falls (fast) and Talus slopes,

• Landslides (fast), and• Avalanches (fast).

Rock fall and Talus Slope:

Rock falls from here

Talus accumulates here

Landslide in

California:

Erosion:

• Water,• Wind, and• Ice (Glaciers).

Water Erosion:Overland Flow and Sheet Erosion

Rills and Gullies

Gully in Iowa Farmland

Wind (Eolian) Erosion:

Star Dunes in the Namib Desert, Namibia

Glacial Erosion:Alpine Glacier on Mt. Rainer, Washington

The Hydrologic Cycle• Introduction

– Series of storage areas of water in the hydrosphere

– Water moves between storage areas

• The Earth’s Hydrologic Cycle…

The Oceans• Four Oceans

Composition of the Atmosphere• Permanent Gases– Nitrogen and oxygen dominate

• Variable Gases– Water Vapor– Carbon Dioxide

– Ozone

Stable components of the Stable components of the atmosphere:atmosphere:

% by Volume% by Volume

78782121

~1~1 trace (0.036)trace (0.036)

Argon (Ar)Argon (Ar)

Gas (Symbol)Gas (Symbol)

Carbon Carbon Dioxide(CODioxide(CO22))

Oxygen (OOxygen (O22))Nitrogen (NNitrogen (N22))

Variable components:

• Water vapor (H2O)• Ozone (03)• Airborne particulates • Greenhouse gases

– Carbon dioxide– Methane– Nitrous oxide– CFCs and other halocarbons

Vertical Structure of the Atmosphere• Temperature

– Thermal layers– Troposphere– Stratosphere– Mesosphere– Thermosphere– Exosphere

• Troposphere– Our weather occurs here

The TroposphereThe Troposphere

• Almost all of our weather occurs in this lowest layer.

• Comprises about 75 to 80% of the mass of the atmosphere.

• Consists of about 78% N, 21% O2, and less than 1% each of Ar, H20 vapor, CO2, and other gases.

Fig. 4.3: The total mass of living matter (biosphere) is much less than that of air and water. On land, life ranges from a few cm to 80 m deep, while in water, the average is 100m.

Distribution of Life, Water, and Air:

Distribution of Life in the Ocean:Fig. 4.4: Most marine life is concentrated in the photic zone. Life is abundant on continental shelves and littoral zones. Within the deep, abyssal plains, there is too little light to support much life. Terrestrial environments comprise 29 percent and aquatic 71 percent.

Ecosystems, Resources, and Energy Flow:Fig. 4.5: An ecosystem describes a system of living and non-living components. A food chain describes energy flow through an ecosystem. Three classes: terrestrial, saltwater, and freshwater.

Fig 4.6: Systems that run on solar energy: basic life processes, life-support processes, and life-threatening processes. Earth’s atmosphere and surface reflect, scatter, and absorb 65 percent.

Insolation within Lower Atmosphere and Surface:

Global Distribution of Insolation:

Fig. 4.7: High latitudes receive low values; middle latitudes, moderate values; and low latitudes, higher values. Note the effect of cloud cover in the equatorial latitudes!

GLOBAL RADIATION BALANCE________________________________________________________

Insolation and Insolation and LatitudeLatitude

Global Air Temp Global Air Temp PatternsPatterns

Global Distribution of Precipitation:

Fig. 4.8: Mean annual precipitation. Note general patterns!

Most abundant elements within the biosphere:

Table 4.1: On page 58.

Biogeochemical Cycle: Carbon Cycle:

Fig. 4.9: Excess CO2 is absorbed by plants, ocean, and lithosphere.

Biogeochemical Cycle: The Oxygen Cycle:

Fig. 4.10: The atmosphere is comprised of about 21 percent O2.

Biogeochemical Cycle: The Nitrogen Cycle:

Fig. 4.11: The atmosphere is comprised of about 78 percent N2.

Biogeochemical Cycle: The Phosphorous Cycle:

Cause-and-Effect Relationships: Biosphere: