geography_skills v1.0.0

name: "geography_skills" description: "Teach and apply real geography: read topographic maps and contour lines, compare map projections, decode Koppen climate zones, and explain why political borders sit where they do. Triggers when the user asks about map reading, topography, climate zones, map projections, borders, or wants geography explained so it sticks."

Geography Skills

Purpose

Make geography usable. This skill covers the four things people actually need from geography: reading a map like a local, understanding what every flat world map gets wrong, reading climate from a letter code, and reading the history behind a border line. Every claim it produces must be verifiable. See Operating Rules.

Workflow

1. Map literacy: read any paper map

Walk the user through, in order:

1. Legend first. Every symbol on the map is defined there. Never guess symbols; they vary by map series (all USGS topo maps share one standard legend, which is why it is worth learning once).
2. Scale. The ratio in the margin (e.g. 1:24,000 on a standard USGS 7.5-minute topo map) means 1 unit on the map = 24,000 units on the ground. At 1:24,000, 1 inch = 2,000 feet, and roughly 2.5 inches = 1 mile. Use bin/mapscale.py to convert any measurement instead of doing it by hand.
3. Grid reference. On US maps use the UTM grid: read eastings first (left to right), then northings (bottom to top), "read right, then up." A 6-figure reference: take the easting line left of the point, estimate tenths across; take the northing line below the point, estimate tenths up.
4. Latitude/longitude frame. Printed at the map edges. On a 7.5-minute map the frame spans 7.5 arc-minutes (1/8 of a degree) per side.

Detailed field technique (paper-strip measuring, shoelace trick for curvy trails, orienting the map) lives in references/map-reading.md.

2. Topography: read the land from contour lines

Brown contour lines connect points of equal elevation. Rules that always hold:

• The contour interval (elevation between adjacent lines) is printed in the margin; commonly 40 feet on USGS 1:24,000 maps. Every fifth line is darker with its elevation labeled: the index contour.
• Lines close together = steep slope. Lines far apart = gentle or flat.
• Concentric circles = hilltop (or a depression if the circles carry inward tick marks).
• V-shapes pointing uphill = valley or drainage. V-shapes pointing downhill = ridge or spur.
• Contours never cross on a standard topo map (a cliff shows as lines merging, nearly touching).

A worked elevation-reading example is in references/map-reading.md. When a user gives you an elevation problem, show the math: (number of intervals crossed) x (contour interval), anchored from the nearest index contour.

3. Projections: why every flat world map is a little wrong

Start from the core tradeoff, stated plainly: you cannot flatten a sphere without distorting something. Every projection chooses what to sacrifice: shape, area, distance, or direction.

Teach the four the user will meet:

| Projection | Year | What it preserves | What it breaks | When to reach for it | |---|---|---|---|---| | Mercator | 1569 | Compass directions; straight lines = constant bearing | Area near poles massively inflated | Navigation charts, web maps (Google Maps) | | Gall-Peters | 1855 | Area (countries shown at true relative size) | Shapes stretched, unfamiliar look | Comparing country sizes fairly | | Robinson | 1963 | Compromise: size and shape both close-ish | Nothing exact, nothing dreadful | Atlases, classroom walls (NatGeo 1988-1998) | | Winkel Tripel | 1921 | Overall minimal distortion | Pacific looks wider than it is | General reference (NatGeo standard since 1998) |

The two anchor facts: Africa is roughly 14 times the land area of Greenland (they look similar on a Mercator), and Alaska looks about three times bigger than Mexico on Mercator while Mexico is actually about 1.3 times bigger than Alaska. Note the current events angle if relevant: the African Union formally moved in August 2025 to have world maps drop Mercator for equal-area projections such as Equal Earth.

Point out the political layer: Mercator's distortion inflates the global north and shrinks the global south. Which distortion a mapmaker picks says what that map is for. Being aware of that is part of reading any world map.

4. Climate zones: decode the Koppen letters

Wladimir Koppen (German botanist and climatologist) built the system at the end of the 19th century, published as a wall map with Rudolph Geiger in 1928. It groups climates by temperature and precipitation thresholds chosen to match vegetation zones. Boundaries on the map are transition zones, not instant shifts.

Teach the five groups, then let bin/koppen_decode.py expand any code the user hands you:

• A tropical: coldest month averages above 18C (64F). Af rainforest, Am monsoon, Aw savanna.
• B dry/arid: the only group defined by moisture, not temperature: evaporation exceeds precipitation. BW desert, BS steppe; second letter h = hot, k = cold.
• C temperate: coldest month between 0C and 18C. Cfa humid subtropical, Cfb oceanic, Csa/Csb Mediterranean.
• D continental: coldest month below 0C, warmest above 10C. Dfa hot-summer, Dfc subarctic. Found mainly across interior Canada and Russia; in the southern hemisphere only in mountains.
• E polar: warmest month below 10C. ET tundra, EF ice cap. H added later for highlands.

The "why it matters" line: the letter tells you what grows there, what farming looks like, and what the seasons feel like. A full code table with examples is in references/climate-and-borders.md.

5. Borders: why the line sits where it does

Teach the boundary types, each with a real example:

• Physical: rivers, mountains, lakes. Rio Grande (US-Mexico), the Pyrenees (Spain-France), the Andes (Chile-Argentina), the Zagros (Iraq-Iran). Rivers shift, so river borders cause disputes: the Rio Grande's drift near El Paso forced the Chamizal Treaty to re-fix the line.
• Geometric: straight lines drawn on the map, often along latitude or longitude. The US-Canada border west of the Great Lakes along the 49th parallel; Indonesia-Papua New Guinea along the 141st meridian. Colonial powers drew these without walking them.
• Ethnic/cultural: drawn around language or religion. India-Pakistan after the 1947 partition. Geometric and colonial lines often split peoples instead: about half of Africa's boundaries are geometric, splitting roughly 177 ethnic groups across states, a direct legacy of borders drawn by outside powers.

Add the definition that sticks: a boundary is an invisible vertical plane. It includes the airspace above and the ground below the surface line.

Output Contract

• Explanations in plain, direct language. One anchor fact per concept, stated with its real numbers.
• Worked examples show the arithmetic (contour math, scale conversion, code decoding), never just the answer.
• When asked "why is the border here," name the boundary type first, then the treaty, river, or survey that drew it.
• Source citations on any claim that names a number, date, or event: at least a named primary source (USGS, National Geographic, a published curriculum, a treaty name).
• Never present an unverified number or event as fact. If a fact cannot be verified with a quick check, cut it or label it as opinion/approximation explicitly.

Operating Rules

1. Accuracy is non-negotiable. Every factual claim in this skill's output must be verified via web search or a primary source. Never invent numbers, dates, quotes, or events. Unverifiable = cut it or frame as opinion. No confident unverified claims, ever.
2. No em dashes, ever. Use commas, periods, colons, or split the sentence. Hyphens inside compound words are fine.
3. No AI filler language. Never "delve", "tapestry", "landscape" as metaphor, "in today's fast-paced world", "it's not X, it's Y" pivots, "moreover/furthermore", "in conclusion", "game-changer", "unlock", "elevate", "supercharge", "let's dive in", stacked triple adjectives, rhetorical-question-then-answer, or hollow inspirational filler. Write like a person talks.
4. Teach from what the user can see. When they describe a map or a place, reference the actual symbols, lines, and letters in front of them.
5. Prefer the CLI helpers over mental math for scale and climate-code work, and show the command you ran.