Geography explainers
Each post covers one idea with tables, diagrams in words and a few questions at the end. The tag on every card gives the coordinates of a real place that shows the topic well.
51.5°N 0.0°
Greenwich, London
Latitude and longitude, explained
How the grid of parallels and meridians pins down any spot on Earth, and how to read and convert coordinates.
64.2°N 51.7°W
Nuuk, Greenland
Map projections: why every flat map distorts
Mercator, equal-area and compromise maps, what each one stretches, and how to pick the right one.
54.5°N 3.2°W
Scafell Pike, England
Map reading basics: scale, legend and compass
Scale, grid references, the three norths and orienting a paper map with a compass.
46.9°N 121.8°W
Mount Rainier, Washington
How to read contour lines on a topographic map
Contour intervals, index contours and the shapes that mark ridges, valleys, saddles and cliffs.
27.7°N 85.3°E
Kathmandu, Nepal
How time zones work, from UTC to the date line
Why the world uses about 15 degrees per hour, where the odd half-hour offsets are, and how to convert times.
3.1°S 60.0°W
Manaus, Brazil
Climate zones and the Köppen system
The five main Köppen groups, what the letter codes mean, and the forces that set a place's climate.
36.1°N 112.1°W
Grand Canyon, Arizona
Landforms explained: how Earth's surface takes shape
Mountains, plateaus, plains, canyons, dunes and coasts, and the forces that build and wear them down.
30.0°N 31.2°E
Cairo, on the Nile
How rivers work: from source to delta
Drainage basins, meanders, floodplains and deltas, plus why river lengths are so hard to pin down.
28.0°N 86.9°E
Mount Everest
How mountain ranges form
Fold, fault-block and volcanic mountains, what tectonic plates have to do with them, and how mountains shape weather.
New to geography? Start here
If you are studying for a class or just want to make sense of maps, read the start-here guide first. It sets out a reading order, a short glossary and some habits that make geography stick. Travelers can jump straight to time zones and climate zones, which answer the two questions that matter most before a trip: what time is it there, and what will the weather be like?
Lines of latitude worth knowing
A handful of parallels come up again and again in geography. They follow from the tilt of Earth's axis, which is about 23.4 degrees, so their positions are rounded here.
| Line | Latitude (about) | What it marks |
|---|---|---|
| North Pole | 90°N | The top of the axis. Every direction from here points south. |
| Arctic Circle | 66.6°N | North of this line there is at least one day a year when the sun does not set, and one when it does not rise. |
| Tropic of Cancer | 23.4°N | The farthest north the sun is ever directly overhead, around the June solstice. |
| Equator | 0° | Halfway between the poles. Day and night are close to 12 hours each all year. |
| Tropic of Capricorn | 23.4°S | The farthest south the sun is ever directly overhead, around the December solstice. |
| Antarctic Circle | 66.6°S | The southern match of the Arctic Circle, with at least one day of midnight sun a year. |
| South Pole | 90°S | The bottom of the axis, on the Antarctic ice sheet. |
Coordinates themselves are covered in latitude and longitude, explained, and why these straight lines curve on some world maps is the subject of map projections.
How we write about geography
We stick to facts that geographers agree on and round numbers that vary by source. When a figure depends on how you measure it, such as the length of a river or the height of a mountain, we say "about" and explain why it varies. Distances and heights are given in metric units with US customary in brackets. Time zone and daylight saving rules change, so we explain how the system works and point you to current sources for the details.
Common questions
Who is this site for?
Middle school, high school and early college students learning physical geography, and travelers who want to read maps, plan around time zones and understand the landscapes they visit. No background is assumed.
What is physical geography?
It is the study of Earth's natural features and processes: landforms, rivers, climate, soils and the forces that shape them. Human geography, by contrast, studies people, cities and economies. Maps and coordinates are tools that both branches use.
Do I need to buy an atlas?
No. A school atlas or a globe helps, and free online maps with a terrain layer cover most of what these posts describe. A paper topographic map of a place you know is the best way to practice reading contour lines.