Geography Fundamentals: Physical and Atmospheric Concepts

Posted on Jan 21, 2026 in Geology

Physical vs Human Geography

Physical Geography focuses on natural systems & processes (weather, climate, landforms). Human Geography focuses on culture, population, and cities.

Atmospheric Structure

  • Pressure & density decrease with height.
  • Temperature pattern by layer:
    • Troposphere: $\downarrow$
    • Stratosphere: $\uparrow$
    • Mesosphere: $\downarrow$
    • Thermosphere: $\uparrow$
  • Inversion: Temperature increases with height in a layer.
  • Temperature $\uparrow$ means molecules move faster.

Maps & Coordinates

  • Global coordinate system: grid for locating places (latitude/longitude).
  • Latitude determines day length; Longitude determines seasons/time zones.
  • Essential map items: legend, title, compass rose, scale.
  • Projections fix Earth’s curvature, but distort size. Cylindrical projections stretch high latitudes (e.g., Greenland, Antarctica).

Seasons & Sun Geometry

  • Caused by Earth’s $\mathbf{23.5^{\circ}}$ tilt. Most intense seasonal change occurs at high latitudes.
  • The Sun is the main energy source.
  • Sun intensity is greatest at solar noon (this is not necessarily the hottest time).
  • Higher latitude means a lower sun angle. Solstice marks the longest/shortest days; Equinox means equal day/night.

Climate Regions

  • Regions are based on temperature/precipitation patterns.
  • Equator $\rightarrow$ tropical; $30^{\circ}$ parallels $\rightarrow$ dry; midlatitudes $\rightarrow$ temperate; poles $\rightarrow$ polar.

General Circulation

  • The single-cell model is a simple concept: warm air rises at the equator & sinks at the poles.
  • The three-cell system (Hadley, Ferrel, Polar) results from Earth’s rotation.
  • This system creates climate patterns: dry zones at $30^{\circ}/90^{\circ}$; wet zones at $0^{\circ}/60^{\circ}$.

Exam 2: Major Concepts

Energy Transfer

  • Conduction: Direct contact; primarily in solids; heat moves hot $\rightarrow$ cold.
  • Convection: Fluid movement (liquid/gas); hot material rises.
  • Radiation: Requires no medium; energy moves away from the source.
  • Sensible heat relates to temperature change; Latent heat relates to phase change.

Diurnal Temperature

  • Maximum temperature occurs in mid-afternoon. Minimum temperature occurs just after sunrise.
  • Clouds tend to warm nights and cool days.
  • Shortwave radiation is incoming; Longwave radiation is outgoing.

Moisture

  • Phase changes include: melting, freezing, evaporation, condensation, sublimation.
  • Key Variables:
    • Saturation Vapor Pressure (SVP) depends on temperature.
    • Mixing ratio is the actual amount of water vapor present.
    • Relative humidity (RH) is vapor content relative to capacity.
  • Saturation is the maximum vapor possible at a given temperature.
  • RH indicates how close the air is to saturation, affecting comfort and cloud likelihood.

Forces & Wind

  • Pressure Gradient Force (PGF) drives wind; Coriolis force causes deflection; Geostrophic wind is the balance between PGF + Coriolis.
  • Surface winds are slowed down by friction.

Earth’s Materials

  • Layers from center out: Core (dense), Mantle, Crust.
  • Lithosphere includes the crust and the upper mantle. The atmosphere/exosphere is above.
  • Density increases with depth (density continuum).

Rocks & Rock Cycle

  • Igneous: Formed from cooled magma.
  • Sedimentary: Formed from compressed sediments.
  • Metamorphic: Formed by intense heat/pressure.
  • The Rock Cycle moves materials through all stages.

Plate Tectonics & Earthquakes

  • Evidence for Continental Drift: matching fossils, fit of continents, similar rock types across oceans.
  • Plate interactions create ridges, mountains, and volcanic arcs. Hotspots are independent of plate boundaries.
  • Earthquakes (EQs) result from stress release along faults.
  • Scales: Richter measures energy released; Mercalli measures damage observed.
  • Notable CA EQs: 1906 San Francisco, 1989 Loma Prieta.
  • Earthquake prediction is not possible; only probabilities can be assessed.

Geomorphology

  • Relief describes the height differences across a landscape.
  • Endogenic processes (internal, like uplift) increase relief. Exogenic processes (external, like weathering/erosion) lower relief.
  • Weathering breaks down material; erosion moves it; deposition drops the material.
  • Geomorphic agents include water, wind, and ice.
  • Punctuated equilibrium suggests long periods of slow change interrupted by sudden events.