Introduction to Physical Geography

Posted on Sep 2, 2024 in Geology

Earth’s Shape and Systems

1. Earth is not perfectly spherical:

  • The equatorial radius is slightly larger than the polar radius.

2. Cryosphere:

  • Includes all forms of frozen water.

3. Biosphere:

  • Encompasses all living organisms and their environments, excluding the atmosphere.

Earth’s Movement and Seasons

4. Perihelion:

  • Occurs in January when Earth is closest to the Sun.

5. Seasons:

  • Caused by the tilt of Earth’s axis.

6. December 22nd:

  • The noon sun is directly overhead at 23.5° S (Tropic of Capricorn).

7. June 22nd:

  • The midnight sun (24 hours of daylight) occurs north of the Arctic Circle.

8. Aphelion:

  • The point in Earth’s orbit where it is farthest from the Sun.

9. Insolation Variation:

  • In mid-June, parts of Alaska receive more insolation than parts of Florida due to longer daylight hours.

10. Daylight Hours:

  • In the Northern Hemisphere summer, daylight hours increase from the equator poleward.

Earth’s Energy Balance and Atmosphere

11. Albedo:

  • The amount of solar radiation reflected off a surface.

12. Greenhouse Gases:

  • Most efficient at absorbing infrared wavelengths of energy.

13. Non-Greenhouse Gas:

  • Nitrogen (N2) is not a significant greenhouse gas.

14. Earth’s Radiation:

  • Primarily emitted as infrared wavelengths.

15. Global Net Radiation:

  • Positive in the tropics (more incoming solar radiation than outgoing), negative in the polar regions (more outgoing than incoming).

16. Abundant Atmospheric Gases:

  • Oxygen (O2) and Nitrogen (N2) are the two most abundant gases.

17. Ozone Layer:

  • Crucial for life as it absorbs harmful ultraviolet (UV) radiation.

Atmospheric Circulation and Pressure Systems

18. Surface Anticyclone:

  • Upper-level air sinks and diverges at the surface.

19. Coriolis Effect:

  • Caused by Earth’s rotation, deflecting moving objects (like air masses) to the right in the Northern Hemisphere and to the left in the Southern Hemisphere.

20. Surface Cyclone:

  • Characterized by converging and rising surface air.

21. Hadley Cell:

  • Sinking air occurs around the subtropics (around 30° latitude).

22. Monsoons:

  • Southern Asia, including India, receives most of its precipitation during the summer monsoon.

23. Polar Jet Stream:

  • Located near the tropopause (boundary between the troposphere and stratosphere) around 60° latitude.

Ocean Currents

24. Surface Ocean Currents:

  • Driven primarily by surface winds.

25. Deep Ocean Currents:

  • Driven by density differences (thermohaline circulation).

26. Water Density:

  • Densest water is cold and has high salinity.

27. El Niño:

  • Characterized by unusually warm waters in the western and central equatorial Pacific Ocean.

28. La Niña:

  • Associated with stronger-than-normal trade winds.

Midterm 2 Topics

This section covers various topics related to weather, climate, Earth’s structure, and more. Please refer to your course materials for detailed explanations and diagrams.

Weather and Climate

  • Condensation: Heat is released when water vapor changes into liquid water.
  • Sleet: Forms when snow melts and refreezes in cold air before reaching the surface.
  • Heat Absorption: Heat is absorbed from the environment when ice changes into liquid water.
  • Interglacial Period: The current geological epoch characterized by warmer temperatures between glacial periods.
  • Proxy Data: Evidence of past climate conditions derived from natural sources like ice cores, tree rings, and sediments.
  • Human Impacts on Climate: Include increased atmospheric CO2 concentrations, changes in surface albedo, and altered greenhouse gas concentrations.
  • Milankovitch Cycles: Long-term variations in Earth’s orbital parameters (eccentricity, obliquity, precession) that influence climate patterns over thousands of years.
  • Vegetation Burning: Impacts climate by changing surface albedo, altering water balance, and releasing greenhouse gases.

Earth’s Interior

  • Seismic Waves: Provide evidence for understanding Earth’s internal structure.
  • Seismic Wave Speed: Determined by the density of the material the waves are passing through.
  • Asthenosphere: The partially molten layer within the upper mantle that allows for the movement of lithospheric plates.
  • Mohorovičić Discontinuity (Moho): A boundary marking a sharp density change between the Earth’s crust and mantle.
  • Transform Boundaries: Plate boundaries where crust is neither created nor destroyed.
  • Oldest Oceanic Crust: Found near continents, as new crust is formed at mid-ocean ridges and spreads outward.
  • Subduction Zones: Occur where tectonic plates converge, and one plate slides beneath the other.
  • Mid-Ocean Ridges: Underwater mountain ranges where new oceanic crust is formed through volcanic activity.

Landforms, Erosion, and Water

  • Landforms: Natural features on Earth’s surface shaped by various geological processes (e.g., mountains, valleys, plains).
  • Running Water: The most significant agent of erosion, shaping landscapes through processes like abrasion and transportation of sediments.
  • Infiltration: The process of water soaking into the ground.
  • Freshwater Storage: Glaciers and ice sheets hold the largest percentage of Earth’s freshwater.
  • Saturated Zone (Phreatic Zone): The zone beneath the water table where all pore spaces in the ground are filled with water.
  • Soil Components: Include organic matter, inorganic matter, gases, and water.
  • Soil Horizons: Distinct layers within a soil profile, each with characteristic properties.
  • Soil Organic Matter Decomposition: Releases CO2 into the atmosphere.
  • Ocean and Freshwater Distribution: Oceans hold approximately 97% of Earth’s water, while freshwater accounts for about 3%.

Additional Notes and Concepts

This section includes brief explanations of key terms and concepts. Refer to your textbook or lecture notes for more in-depth information.

Weathering and Erosion

  • Weathering: The breakdown of rocks, soil, and minerals through contact with Earth’s atmosphere, water, and biological organisms.
  • Erosion: The process of transporting weathered material from one location to another by agents like wind, water, or ice.

Climate Change Processes

  • Natural Internal: Volcanic eruptions, changes in ocean currents.
  • Natural External: Variations in solar output, Milankovitch cycles.
  • Anthropogenic: Deforestation, fossil fuel burning, land use change.

Deforestation and Climate Change

  • Reduced Carbon Uptake: Deforestation diminishes the ability of forests to absorb CO2 through photosynthesis.
  • Increased CO2 Release: Burning and decomposition of trees release stored carbon into the atmosphere.
  • Albedo Changes: Deforestation can alter surface reflectivity, potentially leading to localized warming or cooling.

Earth’s Interior Structure

  • Inner Core: Solid, primarily composed of iron and nickel.
  • Outer Core: Liquid, also primarily iron and nickel.
  • Mantle: Thickest layer, mostly solid rock, but the asthenosphere within the upper mantle behaves plastically.
  • Crust: Outermost layer, divided into oceanic and continental crust.

Continental Drift Evidence

  • Fossil Distribution: Similar fossils found on continents now separated by oceans.
  • Puzzle-Like Fit: Continents fit together like puzzle pieces, suggesting they were once joined.
  • Seafloor Spreading: Magnetic stripes on the ocean floor indicate the formation of new crust at mid-ocean ridges.

Soil Texture and Rainforests

  • Soil Texture Triangle: A tool used to classify soil texture based on the percentages of sand, silt, and clay.
  • Rainforest Soil Fertility: Despite often having nutrient-poor soils, rainforests thrive due to rapid nutrient cycling and adaptations of plants to access nutrients from decomposing organic matter.

Heat Transfer

  • Radiation: Transfer of heat through electromagnetic waves (e.g., sunlight).
  • Conduction: Transfer of heat through direct contact (e.g., touching a hot stove).
  • Convection: Transfer of heat through the movement of fluids (e.g., boiling water).

Adiabatic Processes

  • Dry Adiabatic Lapse Rate: The rate at which a rising parcel of unsaturated air cools (approximately 10°C/km).
  • Environmental Lapse Rate: The rate at which the temperature of the surrounding atmosphere changes with altitude.
  • Atmospheric Stability: Determined by comparing the temperature of a rising air parcel to the temperature of the surrounding environment. If the parcel is cooler, it’s stable; if warmer, it’s unstable.

Carbon Cycle and Biodiversity

These sections cover essential concepts related to the carbon cycle, biodiversity, and conservation. Review your course materials for detailed explanations and examples.

Carbon Cycle

  • Sources: Processes that release carbon into the atmosphere (e.g., fossil fuel burning, respiration, decomposition).
  • Sinks: Processes that remove carbon from the atmosphere (e.g., photosynthesis, ocean uptake).
  • Photosynthesis: The process by which plants use sunlight, CO2, and water to produce energy and oxygen.
  • Respiration: The process by which organisms release energy from organic molecules, producing CO2 as a byproduct.
  • Ocean Acidification: The ongoing decrease in the pH of Earth’s oceans, caused by the uptake of CO2 from the atmosphere.
  • Rock Weathering: A long-term process that removes CO2 from the atmosphere, eventually storing it in rocks and sediments.

Biodiversity and Conservation

  • Biodiversity: The variety of life on Earth, encompassing species, genetic, and ecosystem diversity.
  • Species Range: The geographical area where a particular species is found.
  • Competition: Interaction between organisms for limited resources.
  • Predation: One organism (predator) kills and consumes another (prey).
  • Amensalism: One organism is harmed, while the other is neither harmed nor benefited.
  • Mutualism: Both organisms benefit from the interaction.
  • Ecological Niche: The role and position a species has within its environment.
  • Disturbances: Events that disrupt an ecosystem (e.g., fires, storms).
  • Endemic Species: Species found only in a specific geographic location.
  • Natural Selection: The process by which organisms better adapted to their environment tend to survive and reproduce more successfully.
  • Adaptation: The process of change by which an organism or species becomes better suited to its environment.
  • Endangered Species: Species at risk of extinction.
  • Threatened Species: Species likely to become endangered in the near future.
  • Mass Extinction: A widespread and rapid decrease in biodiversity on Earth.
  • Biodiversity Hotspots: Regions with high concentrations of endemic species and significant threats to biodiversity.