Finding places: hemispheres, latitude and longitude
Geographers use an imaginary grid on the globe.
- Latitude lines run east–west. They measure how far north or south of the equator (0°) a place is, up to 90° at the poles.
- Longitude lines run pole to pole. They measure how far east or west of the prime meridian (0°, through Greenwich, London) a place is, up to 180°.
The equator makes the Northern and Southern Hemispheres; the prime meridian and 180° line make the Eastern and Western Hemispheres. Important lines: Tropic of Cancer (23.5°N), Tropic of Capricorn (23.5°S), Arctic and Antarctic Circles (66.5°N and S).
Time zones
Earth turns 360° in 24 hours, so 15° of longitude = 1 hour. India uses one time zone, 5 h 30 min ahead of Greenwich (UTC+5:30), based on 82.5°E.
Continents and oceans: the physical world
Land covers about 29% of Earth and water about 71%.
Seven continents (area, million km², rounded)
- Asia 44.6: Himalaya with Mount Everest (8,849 m, highest point on land), Siberia, the Gobi desert, rivers like the Yangtze and Ganga.
- Africa 30.4: the Sahara (largest hot desert), the Nile, the Congo rainforest, the East African Rift.
- North America 24.7: the Rockies, the Great Lakes, the Mississippi.
- South America 17.8: the Andes (longest mountain range on land) and the Amazon (largest rainforest, biggest river by water flow).
- Antarctica 14.2: almost all ice, coldest place on Earth.
- Europe 10.2: the Alps, the North European Plain, the Danube and Volga.
- Oceania 8.5: Australia and Pacific islands, the Great Barrier Reef.
Five oceans (million km², rounded)
Pacific 165 (deepest point: Mariana Trench, about 11 km), Atlantic 106, Indian 71, Southern 22, Arctic 14.
World regions: grouping countries
A region is an area that shares something: climate, landforms, culture or economy. Common world regions:
- Europe: Northern, Western, Southern and Eastern Europe; high income, ageing populations.
- Russia and Central Asia: Russia is the largest country by area and spans Europe and Asia; taiga forest, tundra, oil and gas.
- East Asia (China, Japan, Korea): China has about 1.4 billion people and is a giant of manufacturing.
- South Asia (India and neighbours): India is the most populous country (about 1.4 billion), with monsoon farming and fast-growing services.
- Southeast Asia: islands, rainforest, rice farming, busy sea trade.
- Middle East / West Asia and North Africa: hot deserts, scarce water, large oil reserves, old river valleys like the Tigris–Euphrates and the Nile.
- Sub-Saharan Africa: savanna and rainforest, the youngest and fastest-growing population.
- North America, Latin America and Oceania.
Regions are tools for study, not fixed walls; we use physical and relief maps here, not political maps.
Human features and the world of the future
Human features
Population (about 8 billion people), population density, cities, languages, religions, farming, industry and trade. Population is dense in river plains and coasts (Ganga plain, eastern China, Nile valley) and thin in deserts, ice and high mountains.
Big world trends
- Population: growth is slowing; Africa will add the most people, Europe and East Asia are ageing.
- Cities: over half of all people now live in cities; megacities (10 million+) such as Tokyo, Delhi, Shanghai and Lagos.
- Economy: the share of world production in Asia keeps rising.
- Global problems: climate change, water and food supply, loss of forests and species, inequality between rich and poor regions. They need countries to work together.
Key formulas and definitions
- Latitude: 0° at the equator → 90° N or S at the poles
- Longitude: 0° at the prime meridian → 180° E or W
- Time difference: 15° of longitude = 1 hour (4 minutes per 1°)
- Tropical 0–23.5°, temperate 23.5–66.5°, polar 66.5–90°
- Water ≈ 71% of Earth's surface, land ≈ 29%
- Population density = number of people ÷ area (people per km²)
Worked examples
1. A place is at 40°S, 70°W. Which hemispheres is it in, and which climate zone?
S means south of the equator → Southern Hemisphere. W means west of the prime meridian → Western Hemisphere. 40° is between 23.5° and 66.5° → temperate zone. (This is in South America.)
2. It is 12:00 noon at 0° longitude. What is the local Sun time at 75°E?
75 ÷ 15 = 5 hours. East is ahead, so 12:00 + 5 h = 5:00 pm.
3. A region has 300 million people on 4 million km². Find the population density and compare it with Australia (about 3.5 people per km²).
Density = 300,000,000 ÷ 4,000,000 = 75 people per km². That is about 21 times more crowded than Australia (75 ÷ 3.5 ≈ 21).
Common mistakes
- Mixing up latitude and longitude. Latitude lines are flat like the rungs of a ladder ("lat is flat"); longitude lines are long, from pole to pole.
- Thinking Europe is the smallest continent. Oceania (Australia) is smaller.
- Saying the Arctic is a continent. The Arctic is an ocean with floating ice; Antarctica is the frozen continent.
- Thinking the biggest country by area also has the most people. Russia is largest by area, but India and China have far more people.