Map Projections

Study Notes

Map Projections

A way to represent the curved surface of the Earth on a 2D map
Methods to preserve:
- Shape: conformal projections (e.g. Mercator)
- Size: equal-area projections (e.g. Gall-Peters)
- Distance: equidistant projections
- Direction: azimuthal projections
Common map projections:
- Mercator: preserves shape, but distorts size and distance at high latitudes
- Gall-Peters: preserves size, but distorts shape
- Azimuthal: preserves direction, but distorts shape and size

Geographic Coordinates

System to locate points on the Earth's surface using latitude and longitude
Latitude:
- Measures distance from the Equator (0° to 90° N or S)
- Also known as parallels
- Lines that run east-west
Longitude:
- Measures distance from the Prime Meridian (0° to 180° E or W)
- Also known as meridians
- Lines that run north-south
Coordinates are written in the format: latitude, longitude (e.g. 37.7749° N, 122.4194° W)
Latitude and longitude can be measured in degrees, minutes, and seconds (e.g. 37° 46' 30" N, 122° 25' 10" W)

Map Projections

Map projections are methods to represent the curved Earth's surface on a 2D map
Four key properties to preserve in map projections:
- Shape
- Size
- Distance
- Direction
Conformal projections preserve shape, but can distort size and distance
Equal-area projections preserve size, but can distort shape
Equidistant projections preserve distance, but can distort shape and size
Azimuthal projections preserve direction, but can distort shape and size

Common Map Projections

Mercator projection:
- Preserves shape
- Distorts size and distance at high latitudes
- Used for navigation, as it preserves shape and direction
Gall-Peters projection:
- Preserves size
- Distorts shape
- Used for educational and cultural purposes, as it presents a more accurate representation of the Earth's surface
Azimuthal projection:
- Preserves direction
- Distorts shape and size
- Used for mapping small areas, such as cities or neighborhoods

Geographic Coordinates

Geographic coordinates are a system to locate points on the Earth's surface using latitude and longitude
Latitude:
- Measures distance from the Equator (0° to 90° N or S)
- Also known as parallels
- Runs east-west
Longitude:
- Measures distance from the Prime Meridian (0° to 180° E or W)
- Also known as meridians
- Runs north-south
Coordinates are written in the format: latitude, longitude (e.g. 37.7749° N, 122.4194° W)
Coordinates can be measured in degrees, minutes, and seconds (e.g. 37° 46' 30" N, 122° 25' 10" W)

Geographic Coordinates

Geographic coordinates are a way to locate a point on the Earth's surface using longitude and latitude.

Latitude (φ)

Measures distance north or south of the Equator (0° latitude).
Ranges from 0° at the Equator to 90° at the North or South Pole.
Latitude is divided into degrees, minutes, and seconds (e.g., 40° 26' 46" N).
1 degree of latitude is equal to approximately 111 kilometers (69 miles).

Longitude (λ)

Measures distance east or west of the Prime Meridian (0° longitude).
Ranges from 0° at the Prime Meridian to 180° east or west.
Longitude is divided into degrees, minutes, and seconds (e.g., 74° 0' 23" W).
1 degree of longitude is equal to approximately 111 kilometers (69 miles) at the Equator.

Key Concepts

Geographic coordinate system is a system that uses latitude and longitude to locate points on the Earth's surface.
The Prime Meridian is an imaginary line that passes through Greenwich, England, and is designated as 0° longitude.
The Equator is an imaginary line that runs around the middle of the Earth, dividing it into the Northern and Southern Hemispheres, and is designated as 0° latitude.

Description

Learn about ways to represent the Earth's curved surface on a 2D map, including conformal, equal-area, equidistant, and azimuthal projections. Compare common map projections like Mercator and Gall-Peters.