Geography

1. Geography and Physical Geography

• Geography: The study of Earth's landscapes, environments, and the relationships between people and their environments.

• Physical Geography: Focuses on natural features and processes of the Earth, such as landforms, climate, and ecosystems.

• 4 Spheres of the Environment:

  1. Atmosphere: The layer of gases surrounding Earth.

  2. Hydrosphere: All water on Earth (oceans, rivers, lakes, groundwater).

  3. Lithosphere: Earth's solid outer layer (crust and upper mantle).

  4. Biosphere: The zone of life, where living organisms exist.

2. Atmosphere

• Atmospheric Gases:

  1. Nitrogen (78%), Oxygen (21%), Argon (0.9%), Carbon Dioxide (0.04%), and trace gases.

• Pressure Profile: Atmospheric pressure decreases with altitude.

• Temperature Profile:

  1. Troposphere: Temperature decreases with altitude.

  2. Stratosphere: Temperature increases due to ozone absorption of UV radiation.

  3. Mesosphere: Temperature decreases.

  4. Thermosphere: Temperature increases due to solar radiation.

• 4 Layers of the Atmosphere:

  1. Troposphere: Closest to Earth, where weather occurs.

  2. Stratosphere: Contains the ozone layer.

  3. Mesosphere: Protects Earth from meteoroids.

  4. Thermosphere: Absorbs solar radiation.

• Ozone: A molecule (O₃) in the stratosphere that absorbs UV radiation.

• Ozone Hole: A thinning of the ozone layer, primarily over Antarctica, caused by chlorofluorocarbons (CFCs).

3. Temperature

• Earth/Sun Relationships:

  • Earth’s tilt (23.5°) and orbit around the sun cause seasons.

• Equinoxes: Equal day and night (March 20-21 and September 22-23).

• Solstices: Longest and shortest days of the year (June 21-22 and December 21-22).

• Tropic of Cancer/Capricorn: Latitudes (23.5°N and 23.5°S) where the sun is directly overhead during solstices.

• Arctic/Antarctic Circles: Latitudes (66.5°N and 66.5°S) marking the boundary of the polar regions.

• Sun Overhead: The sun is directly overhead at the Tropic of Cancer during the June solstice and the Tropic of Capricorn during the December solstice.

• Calculating Sun Angles: Use latitude and the sun’s declination to determine the angle of the sun at noon.

• Radiation Laws:

  • Shortwave radiation: Incoming solar radiation (high energy).

  • Longwave radiation: Outgoing terrestrial radiation (low energy).

• Albedo: The reflectivity of a surface (e.g., snow has high albedo).

• Greenhouse Effect: Trapping of longwave radiation by greenhouse gases (CO₂, H₂O, CH₄), warming the Earth.

• Radiation Balance: The balance between incoming solar radiation and outgoing terrestrial radiation.

• Sensible Heat: Heat transferred through conduction and convection.

• Latent Heat: Heat absorbed or released during phase changes (e.g., evaporation, condensation).

• Bowen Ratio: The ratio of sensible heat to latent heat transfer.

• Temperature Terms:

  • Daily Temperature Pattern: Highest in the afternoon, lowest just before sunrise.

  • Annual Temperature Pattern: Hottest in summer, coldest in winter.

• Continents vs. Oceans: Land heats and cools faster than water, leading to greater temperature variations.

• Degree Days:

  • Heating Degree Days (HDD): Measure of heating demand.

  • Cooling Degree Days (CDD): Measure of cooling demand.

  • Growing Degree Days (GDD): Measure of heat accumulation for plant growth.

4. Precipitation

• Moisture Terms:

  • Specific Humidity: Mass of water vapor per unit mass of air.

  • Vapor Pressure: Pressure exerted by water vapor in the air.

  • Saturation Vapor Pressure: Maximum vapor pressure at a given temperature.

  • Relative Humidity: Ratio of actual vapor pressure to saturation vapor pressure.

• Lapse Rates:

  • Environmental Lapse Rate: Rate of temperature decrease with altitude in the atmosphere.

  • Adiabatic Lapse Rates: Rate of cooling/warming of rising/sinking air.

    • Dry Adiabatic Lapse Rate (DALR): 10°C/km.

    • Wet Adiabatic Lapse Rate (WALR): 5-6°C/km.

• Atmospheric Stability:

  • Stable Atmosphere: Resists vertical movement.

  • Unstable Atmosphere: Encourages vertical movement.

  • Conditionally Unstable: Stable if unsaturated, unstable if saturated.

• Lifting Mechanisms:

  • Orographic Lifting: Air rises over mountains.

  • Frontal Lifting: Air rises along weather fronts.

  • Convection: Air rises due to heating.

• Fog: A cloud at ground level, formed by cooling or evaporation.

• Cloud Types:

  • Stratus: Layered clouds.

  • Cumulus: Puffy, vertical clouds.

• Precipitation Types:

  • Showers: Short, intense precipitation.

  • Drizzle: Light, continuous precipitation.

  • Frozen Precipitation: Snow, sleet, hail.

5. Wind

• Pressure Gradient Force: Drives air from high to low pressure.

• Coriolis Effect: Deflects wind due to Earth’s rotation (right in the Northern Hemisphere, left in the Southern Hemisphere).

• Friction: Slows wind near the surface, reducing the Coriolis effect.

• Geostrophic Winds: Winds that flow parallel to isobars, balanced by pressure gradient and Coriolis forces.

• Surface Winds: Affected by friction, blowing at an angle to isobars.

• Cyclones/Anticyclones:

  • Cyclones: Low-pressure systems with inward, counterclockwise (NH) or clockwise (SH) winds.

  • Anticyclones: High-pressure systems with outward, clockwise (NH) or counterclockwise (SH) winds.

• Global Circulation Patterns:

  • ITCZ (Intertropical Convergence Zone): Low-pressure zone near the equator.

  • Subtropical Highs: High-pressure zones at 30°N and 30°S.

  • Polar Front Lows: Low-pressure zones at 60°N and 60°S.

  • Polar Highs: High-pressure zones at the poles.

• Wind Belts:

  • Trade Winds: Easterly winds from 0°-30° latitude.

  • Midlatitude Westerlies: Winds from 30°-60° latitude.

  • Polar Easterlies: Winds from 60°-90° latitude.

• Hadley Cell: Circulation cell between the equator and 30° latitude.

• Global Precipitation Patterns: Heavy precipitation near the equator and midlatitudes, dry conditions near 30° latitude.