Physical Geography study guide Exam 1

MAPS

- What are maps?

Visual representations of spatial data, showing locations and relationships on Earth’s surface.

- Scale – small vs. large:

- Small scale = shows large area, less detail (e.g., world map).

- Large scale = shows small area, more detail (e.g., city map).

- Projections – what they do, what they compromise:

Convert 3D Earth to 2D. Always involve distortions—either in shape, area, distance, or direction.

- Latitude & longitude:

- Latitude: Horizontal lines (0° at Equator to 90° at poles).

- Longitude: Vertical lines (0° at Prime Meridian, up to 180° east/west).

- Contour lines:

Lines of equal elevation; close lines = steep terrain, wide spacing = gentle slope.

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### SEASONS

- Earth-sun relationships:

Caused by Earth’s axial tilt (23.5°) and orbit around the sun.

- Solstices & equinoxes:

- June solstice: ~June 21 – Subsolar point at Tropic of Cancer (23.5°N).

- December solstice: ~Dec 21 – Subsolar point at Tropic of Capricorn (23.5°S).

- March/Sept equinoxes: ~March 21 & Sept 21 – Subsolar point at Equator (0°).

- Insolation:

Incoming solar radiation; varies with latitude and time of year.

- Subsolar point:

Point on Earth receiving direct (90°) solar rays. Moves between 23.5°N and 23.5°S annually.

- Subsolar proximity effects:

- Closer = longer days, higher sun angle, more insolation.

- Further = shorter days, lower sun angle, less insolation.

- Aphelion & perihelion:

- Aphelion: Farthest from sun (~July).

- Perihelion: Closest to sun (~January).

Earth’s orbit is elliptical, but seasons are due to tilt, not distance.

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### ENERGY & THE ATMOSPHERE

- Air pressure & elevation:

Pressure decreases with altitude.

- Normal lapse rate:

6.4°C per 1000 meters (average rate of cooling with elevation).

- Albedo:

Reflectivity of a surface.

- High albedo: Snow, ice (reflects more).

- Low albedo: Asphalt, forests (absorbs more).

- Urban heat island:

Cities are warmer due to human activity, low albedo surfaces, and reduced vegetation.

- Daily temperature pattern:

- Coldest just after sunrise.

- Warmest mid to late afternoon (lag after peak insolation).

- Heat transfer mechanisms:

- Conduction: Direct contact (e.g., touching a hot rock).

- Convection: Fluid movement (e.g., boiling water or rising air).

- Radiation: Energy via waves (e.g., sun to Earth).

- 6 Controls on global temperatures:

1. Latitude: Affects sun angle and insolation.

2. Altitude: Higher = cooler.

3. Cloud cover: Moderates temperature.

4. Land-water heating differences: Water moderates more than land.

5. Ocean currents: Warm or cool regions.

6. Continentality: Inland = higher temperature range.

- Climograph interpretation:

- Temperature and precipitation data.

- High seasonality = higher latitudes.

- Consistent temps = equatorial.

- Low temp range & high humidity = maritime.

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### ATMOSPHERIC PRESSURE & WINDS

- Global wind patterns:

- Polar Easterlies: Cold, from east near poles.

- Westerlies: Mid-latitudes, from west.

- NE/SE Trades: Blow toward equator from subtropics.

- ITCZ: Intertropical Convergence Zone – rising air, clouds, and rain.

- Persistent pressure zones:

- High pressure (H): Sinking air, dry (e.g., subtropics – deserts).

- Low pressure (L): Rising air, moist (e.g., equator – rainforests).

- Aridity patterns:

- Subtropical highs = dry.

- Equatorial lows = wet.

- High vs. low pressure systems:

- High (anticyclone): Clockwise outflow in N. Hemisphere, fair weather.

- Low (cyclone): Counterclockwise inflow in N. Hemisphere, stormy.

- Wind causes:

Differences in air pressure.

- Isobar:

Line of equal pressure on a map.

- 3 Controls on wind:

1. Pressure gradient force (PGF): Air moves from high to low pressure.

2. Coriolis effect: Deflects right in Northern Hemisphere, left in Southern.

3. Friction: Slows wind near surface, reduces Coriolis effect.

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