🏝️Earth Science Unit 2 – Earth's Systems and Cycles

Key Concepts and Definitions

• Earth's systems include the geosphere (solid Earth), hydrosphere (water), atmosphere (air), and biosphere (living organisms)
• Cycles describe the continuous movement and exchange of materials between Earth's systems
  • Examples include the water cycle, carbon cycle, and rock cycle
• Feedback loops can amplify (positive feedback) or dampen (negative feedback) changes in Earth's systems
• Albedo measures the reflectivity of a surface (snow has high albedo, absorbing less solar radiation)
• Anthropogenic factors are human activities that influence Earth's systems (deforestation, fossil fuel combustion)
• Biogeochemical cycles involve the transfer of chemical elements between living organisms and the physical environment
• Gaia hypothesis proposes that Earth's systems interact to maintain conditions suitable for life
• Milankovitch cycles describe long-term variations in Earth's orbit and axis tilt that affect climate

Earth's Major Systems

• Geosphere consists of the solid Earth, including the crust, mantle, and core
  • Crust is the thin, outermost layer of the Earth (oceanic crust, continental crust)
  • Mantle is the layer between the crust and core, comprising most of Earth's volume
  • Core is the innermost layer, divided into the liquid outer core and solid inner core
• Hydrosphere encompasses all water on Earth's surface and underground (oceans, lakes, rivers, groundwater, ice caps)
• Atmosphere is the gaseous layer surrounding the Earth, composed primarily of nitrogen and oxygen
  • Troposphere is the lowest layer where weather occurs
  • Stratosphere contains the ozone layer, which absorbs harmful UV radiation
• Biosphere includes all living organisms on Earth (plants, animals, microorganisms)
• Earth's systems constantly interact and exchange energy and matter through various cycles and processes

The Water Cycle

• Evaporation occurs when water changes from liquid to gas, primarily due to solar energy
  • Transpiration is the release of water vapor from plants through their leaves
• Condensation happens when water vapor cools and forms liquid water droplets (clouds, fog)
• Precipitation is the falling of water from the atmosphere to the Earth's surface (rain, snow, hail)
• Infiltration describes the movement of water into the soil and groundwater
  • Percolation is the downward movement of water through soil and rock layers
• Runoff is the flow of water over the Earth's surface, eventually reaching streams, rivers, and oceans
• Groundwater storage occurs in aquifers, which are permeable rock layers that hold water
• Sublimation is the direct change of water from solid (ice) to gas (water vapor), skipping the liquid phase

The Carbon Cycle

• Photosynthesis is the process by which plants convert carbon dioxide and water into glucose and oxygen using solar energy
  • Carbon dioxide is absorbed from the atmosphere, and oxygen is released as a byproduct
• Respiration releases stored energy in glucose, consuming oxygen and producing carbon dioxide (performed by plants, animals, and decomposers)
• Decomposition breaks down dead organic matter, releasing carbon dioxide and nutrients back into the environment
• Fossil fuel formation occurs when organic matter is buried and subjected to high pressure and temperature over millions of years (coal, oil, natural gas)
• Combustion of fossil fuels releases stored carbon back into the atmosphere as carbon dioxide
• Ocean absorption dissolves atmospheric carbon dioxide in seawater, forming carbonic acid and lowering ocean pH (ocean acidification)
• Weathering of rocks consumes atmospheric carbon dioxide in chemical reactions, forming carbonate minerals
• Volcanic eruptions release carbon dioxide from the Earth's interior back into the atmosphere

The Rock Cycle

• Igneous rocks form from the cooling and solidification of magma (intrusive) or lava (extrusive)
  • Examples include granite (intrusive) and basalt (extrusive)
• Sedimentary rocks form from the compaction and cementation of sediments (rock fragments, organic matter, chemical precipitates)
  • Examples include sandstone, limestone, and shale
• Metamorphic rocks form when pre-existing rocks are subjected to high pressure and temperature, causing physical and chemical changes
  • Examples include marble (metamorphosed limestone) and gneiss (metamorphosed granite)
• Weathering breaks down rocks into smaller fragments through physical (mechanical) and chemical processes
  • Physical weathering includes freeze-thaw cycles and abrasion
  • Chemical weathering involves dissolution and reactions with water and acids
• Erosion is the transport of weathered rock fragments by water, wind, or ice
• Deposition occurs when eroded sediments settle and accumulate in layers (deltas, floodplains, ocean floors)
• Uplift and exposure bring buried rocks back to the surface through tectonic processes (mountain building)

Climate and Weather Patterns

• Climate describes the long-term average weather conditions in a specific area
  • Factors influencing climate include latitude, altitude, ocean currents, and atmospheric circulation patterns
• Weather refers to short-term atmospheric conditions (temperature, humidity, precipitation, wind)
• Global wind patterns are driven by uneven heating of the Earth's surface and the Coriolis effect
  • Examples include trade winds, westerlies, and polar easterlies
• Ocean currents redistribute heat and moisture globally, influencing regional climates (Gulf Stream, Kuroshio Current)
• Jet streams are fast-moving air currents in the upper atmosphere that steer weather systems
• El Niño and La Niña are periodic fluctuations in ocean temperatures and atmospheric pressure in the Pacific Ocean, affecting global weather patterns
• Monsoons are seasonal wind patterns that bring heavy rainfall to tropical regions (South Asia, West Africa)
• Greenhouse effect is the warming of the Earth's surface due to the absorption of infrared radiation by atmospheric gases (carbon dioxide, water vapor)

Human Impact on Earth's Systems

• Deforestation removes trees, reducing carbon storage and altering local water cycles and biodiversity
  • Causes include agriculture, logging, and urbanization
• Fossil fuel combustion releases greenhouse gases, contributing to global warming and climate change
  • Effects include rising sea levels, more frequent extreme weather events, and shifts in species distributions
• Urbanization alters local climates through the urban heat island effect and changes in surface runoff and infiltration
• Agriculture can lead to soil erosion, nutrient depletion, and water pollution from fertilizers and pesticides
  • Irrigation diverts water from natural systems and can cause salinization of soils
• Overfishing disrupts marine food webs and can lead to the collapse of fish populations
• Invasive species introduced by human activities can outcompete native species and alter ecosystem dynamics
• Habitat fragmentation due to human infrastructure (roads, dams) can isolate populations and hinder species migration
• Conservation efforts aim to protect and restore natural systems (protected areas, sustainable resource management)

Practical Applications and Case Studies

• Studying Earth's systems helps predict and mitigate natural hazards (earthquakes, volcanic eruptions, hurricanes)
  • Example: monitoring seismic activity and volcano deformation to issue early warnings
• Understanding the water cycle informs water resource management and flood control
  • Example: constructing dams and levees to regulate river flow and prevent flooding
• Knowledge of the carbon cycle is crucial for developing strategies to reduce greenhouse gas emissions and combat climate change
  • Example: implementing carbon taxes and investing in renewable energy sources
• Analyzing the rock cycle helps locate and extract valuable mineral resources (ores, fossil fuels)
  • Example: using seismic surveys and geological mapping to identify oil and gas reserves
• Climate and weather data are used in agriculture, transportation, and energy production
  • Example: using seasonal forecasts to optimize crop planting and harvesting schedules
• Recognizing human impacts on Earth's systems informs environmental policies and conservation efforts
  • Example: establishing marine protected areas to restore coral reefs and fisheries
• Interdisciplinary research combines knowledge from multiple fields to address complex environmental challenges
  • Example: collaborations between geologists, ecologists, and social scientists to develop sustainable land-use plans