Chapter 5: Ecosystems and the Physical Environment
Gaia Theory- The hypotheses that Earth’s organisms adjust to the environment to keep it
habitable for life. (86)
Biogeochemical Cycles- The five different cycles involving logical, geological, and
chemical interactions. (87)
Biogeochemical Cycles
The Carbon Cycle- The Global circulation of carbon from the environment to living
organisms and back to the environment. (87)
Diagram of the Carbon Cycle (above).
Fossil Fuels- Vast deposits of Carbon compounds formed from the remains of
ancient organisms. (87)
Combustion- The act of carbon in oil, natural gas, and wood returning into the
atmosphere by burning.
The Nitrogen Cycle- The Global circulation of nitrogen from the environment to
living organisms and back to the environment. (89)
Nitrogen fixation- the conversion of gaseous nitrogen to ammonia (NH3). (90)
Nitrification- the conversion of ammonia (NH3) or ammonium (NH+4, formed when
water reacts with ammonia) to nitrate (NO-3). (90)
Ammonification- The conversion of biological nitrogen compounds into ammonia (NH3)
and ammonium ions (NH+4).
Denitrification- The reduction of nitrate (NO-3) to gaseous nitrogen.
The Phosphorus cycle- The global circulation of phosphorus from the environment to
living organisms and back to the environment.
The Sulfur Cycle- The global circulation of sulfur from the environment to living
organisms and back to the environment.
The Hydrologic Cycle- The global circulation of water from the environment to living
organisms and back to the environment.
Transpiration- The loss of water vapor from land plants, adds water the atmosphere.
Estuaries- Area where freshwater meets the ocean.
Runoff- The movement of water from land to rivers, lakes, wetlands, and the ocean.
Watershed- The area of land drained by runoff.
Groundwater- Freshwater stored in underground caverns and porous layers of rock.
Some Human Effects on Biogeochemical Cycles
*Since Industrial Revolution in 1850 society have used a lot of energy.
Nitrogen Oxides- When fossil fuels are burned – in automobiles, for example- the high
temperatures of combustion convert some atmospheric nitrogen to nitrogen oxides.
Photochemical smog- produced by nitrogen oxides (above definition) .
Acid deposition- when nitrogen oxides react with water in the atmosphere to form acids
that then leave the atmosphere and cause the pH of surface waters and soils to decrease.
Aerosols- Tiny particles of air pollution consisting mostly of sulfates, nitrates, carbon,
mineral dust, and fly ash- are produced largely from fossil fuel combustion and the
burning of forest.
*The sun makes life on Earth possible, without the energy from the sun, the temperature
on earth would reach absolute zero (273k).
Albedo- The proportional reflectance of solar energy from Earth’s surface, commonly
expressed as a percentage.
Temperature Changes With Latitude
*Because the Earth is a sphere, the suns energy hits different spots of the earth more so
then others.
*The suns rays hit vertically near the equator, making the energy more concentrated and
producing higher temperatures.
*Rays of light entering the atmosphere obliquely near the poles pass through a deeper
envelope of air then light near the equator. This causes the suns energy to be more
scattered and reflected back to space. Temperatures are lower near the poles.
Temperature Changes with Season
*Seasons are determined primarily by Earth’s inclination on its axis.
* March 21- September 22 The Northern Hemisphere tilts towards the sun.
* September 22- March 21 The Southern Hemisphere tilts towards the sun.
Layers of the Atmosphere
* The Atmosphere contains five layers.
Layer
Troposphere
Stratosphere
Mesosphere
Thermosphere
Exosphere
Height
10km (6.2mi)
10-45km (6.2-28mi)
45-80km (28-50mi)
80-500km (50-310mi)
Begins 500km (310mi)
Atmospheric Circulation
Carioles effect- The influence of Earth’s rotation, witch tends to turn fluids (air and
water) toward the right in the Northern Hemisphere and toward the left in the Southern
Hemisphere.
*Atmospheric circulation transports heat from the equator to the poles. The greatest solar
energy input occurs at the equator, heating air most strongly in that area. The air rises
travels toward the poles, and cools in the process so that much of it descends again at
around 30 degrees latitude in both hemispheres. At higher latitudes, the patterns of air
circulation are more complex.
Surface Winds- The atmosphere exhibits complex horizontal movements commonly
called winds. The nature of wind, with its turbulent gust, eddies, and lulls, is difficult to
understand or protect. This results in part from the differences in atmospheric pressure
and from the Earth’s rotation.
Polar Easterlies- Prevailing winds that generally blow from the northeast near the North
Pole or from the southeast to the south pole
Westerlies- Winds that generally blow in the multitudes from the southwest in the
Northern Hemisphere or from the northwest in the southern hemisphere.
Trade winds- Tropical winds that generally blow from the northeast in the northern
hemisphere or from the southeast in the southern hemisphere.
Patterns of Circulation in the Ocean
Currents- Produced by the persistent prevailing winds blowing over the ocean.
Gyres- Large, circular ocean current systems that often encompass and entire ocean
basin.
*The position of land masses effects ocean circulation.
Verticle Mixing of Ocean Water
*The varying density (mass per unit volume) of seawater affects deep-ocean currents.
* Cold salty water is denser then warmer, less salty water.
Ocean Interactions with the Atmosphere
El Niño- Southern Oscillation (ENSO)- A periodic, large-scale warming of surface
waters of the tropical Eastern Pacific ocean that temporarily alters both ocean and
atmospheric circulation patterns.
La Niña- (Spanish, “little girl”) occurs when the surface water temperature in the eastern
Pacific ocean becomes unusually cool.
Climate- The average weather conditions that occur in a place over a period of time.
Precipitation- Refers to any form of water, such as rain, snow, sleet, and hail, that falls
from the atmosphere.
Rain Shadow- Dry conditions, often on a regional scale, that occur on the leeward side
of a mountain barrier; the passage of moist air across the mountains removes most of the
moisture from the air.
Tornado- (Twister) A powerful, rotating funnel of air associated with severe
thunderstorms.
Tropical Cyclones- giant, rotating tropical storms with winds of at least 119km per hour
(74mi per hour)
Plate Tectonics- The study of the processes by which the lithospheric plates move over
the asthenosphere.
Plate Boundaries- Any area where two plates meet.
Subduction- When two plates grind together, one of them sometimes descends under the
other.
Magma- When rock meets the melting point, forming pockets of molten rock.
Lava- Magma that reaches the surface.
Hot Spot- a rising plume of magma that flowed from an opening in the crust.
Seismic waves- vibrations that spread through the rocks rapidly in all directions.
Faults- Fractures where rock moves forward, backward, up, and down, or from side to
side.
Focus- The site where an earthquake begins.
Epicenter- Directly above the focus, at the Earth’s surface.