2. Physical Geography: Landforms, Climate, and Biomes

Physical geography studies the natural features of Earth's surface — its shape, climate, and ecosystems.

Major Landforms

• Mountains — high, steep landforms formed by tectonic forces or volcanic activity. They influence climate by forcing air upward (which cools and drops rain on the windward side, leaving a dry rain shadow on the leeward side).
• Plains — large, flat or gently rolling areas. Often fertile and heavily farmed (the Great Plains of North America; the North European Plain).
• Plateaus — elevated flat areas, sometimes called 'tablelands' (the Tibetan Plateau, the Colorado Plateau).
• Valleys and River Basins — low areas carved by rivers. Rivers deposit sediment to form deltas at their mouths, creating fertile land.
• Deserts — areas receiving very little precipitation (less than 250 mm/year). Can be hot (Sahara) or cold (Gobi).

Climate

Climate is the long-term average of weather conditions (temperature, precipitation, wind) in a region. Key factors that determine climate:

• Latitude — areas near the Equator receive direct sunlight year-round and are hot; polar regions receive indirect sunlight and are cold.
• Altitude — higher elevations are cooler (approximately 6.5°C colder per 1,000 m gained).
• Proximity to water — oceans moderate temperatures (coastal areas are neither very hot in summer nor very cold in winter); interiors have extreme seasonal swings.
• Ocean currents — warm currents (Gulf Stream) warm nearby coastlines; cold currents cool them.
• Wind patterns — global wind belts carry moisture or dry air.

Climate Zones from Equator to poles: Tropical (hot, wet or wet-and-dry) → Subtropical (hot, often dry) → Temperate (moderate) → Subarctic (cold, short summers) → Polar (permanently cold).

Biomes

A biome is a large region defined by its climate, vegetation, and animal life:

• Tropical rainforest — near the Equator; hot and wet year-round; highest biodiversity on Earth.
• Savanna — tropical grassland with distinct wet and dry seasons (Africa, Brazil's cerrado).
• Desert — hot or cold; very dry; sparse, drought-adapted vegetation.
• Temperate grassland — moderate rainfall; fertile soils (prairies, steppes, pampas).
• Temperate deciduous forest — four seasons; trees shed leaves in autumn (eastern North America, Europe).
• Boreal forest (Taiga) — cold, long winters; coniferous trees (Canada, Russia, Scandinavia).
• Tundra — very cold; permafrost; no trees; near the poles and on high mountains.

Natural Processes That Shape the Land

• Tectonic plates move slowly, building mountains (collision), creating rift valleys (spreading), and causing earthquakes and volcanoes.
• Erosion and deposition by water, wind, and ice continuously reshape the surface.

⚠️ Common misconception: deserts are always hot and sandy. Many deserts are cold (Antarctica is technically the world's largest desert — it receives less than 200 mm of precipitation per year). Desert is defined by low precipitation, not high temperature.

💡 Tip: remember the pattern — moving away from the Equator, you generally move from tropical to temperate to polar, and from wet forest to grassland to desert (depending on rainfall) along each latitude band.