What Is the Tropical Climate?
The tropical climate is found in a broad band around the equator, roughly between 23.5°N (Tropic of Cancer) and 23.5°S (Tropic of Capricorn). Countries in this zone include Brazil, the Democratic Republic of Congo, Indonesia, and Malaysia.
Key characteristics:
- Hot all year: Average temperatures are typically 25–30°C throughout the year.
- No cold season: There is little variation in temperature between months.
- High rainfall: Annual rainfall often exceeds 2000 mm.
Why Is It So Hot Near the Equator?
The equatorial regions receive direct, concentrated sunlight throughout the year. This is because:
- The Sun is always high in the sky near the equator — sunlight hits almost perpendicularly.
- The energy is concentrated over a small area, making it very intense.
- Near the poles, the same amount of sunlight is spread over a much larger area (at a lower angle), making it weaker.
The equator receives about 2.5 times more solar energy per square metre than the poles. This solar energy drives the entire global climate system — warm air at the equator rises, creating areas of low pressure and heavy rainfall, while cool air descends around 30°N and 30°S, creating hot, dry desert zones.
Types of Tropical Climate
Tropical rainforest climate (Af): Rain every month, no dry season. Examples: Amazon Basin (Brazil), Congo Basin (Africa), Borneo (Southeast Asia).
Tropical monsoon climate (Am): Very heavy rainfall in a wet season, short dry season. Examples: Bangladesh, southwestern India.
Tropical savanna climate (Aw): Distinct wet and dry seasons. Typical in sub-Saharan Africa and parts of Brazil. Supports grasslands (savanna) with scattered trees.
The Tropical Rainforest Ecosystem
Areas with year-round heavy rainfall support tropical rainforests — the most biodiverse ecosystems on Earth:
- Biodiversity: A single hectare of Amazon rainforest may contain more tree species than in all of Europe.
- Layers: Emergents (tallest trees), canopy (closed layer 30 m up), understorey, forest floor.
- Nutrient cycling: Heavy rain leaches nutrients from soil quickly; trees recycle nutrients very efficiently.
Tropical rainforests are sometimes called the "lungs of the Earth" because they absorb large amounts of carbon dioxide and produce oxygen through photosynthesis. They also play a key role in rainfall — transpiration from the vast tree canopy contributes to cloud formation and rainfall not just locally but in regions thousands of kilometres away.
Climate Graphs: Tropical
A climate graph for a tropical rainforest location (e.g. Manaus, Brazil) shows:
- Temperature line: stays flat and high (around 26–27°C) all year.
- Rainfall bars: high every month (always above 60–80 mm), often exceeding 200–300 mm in wetter months.
Real world: The Amazon rainforest and Brazil's soya boom
Brazil contains over 60% of the Amazon rainforest — the world's largest tropical rainforest, home to roughly 10% of all species on Earth. However, since the 1970s, large sections have been cleared for cattle ranching and soya farming (Brazil is now the world's largest soya exporter). Deforestation reduces rainfall in the region and releases stored carbon. Satellite data show that some areas are now emitting more CO₂ than they absorb — a sign of ecosystem collapse.
Real world: Rice farming in Southeast Asia
The tropical monsoon climate of Southeast Asia — Vietnam, Thailand, Bangladesh, Indonesia — has enabled rice cultivation for thousands of years. Wet-season flooding of paddy fields provides water and nutrients. Vietnam grows rice twice a year in the Mekong Delta, exporting over 6 million tonnes annually. The entire agricultural calendar is built around the wet and dry seasons driven by the tropical monsoon system.
Real world: Tourism in tropical destinations
The Maldives, Bali (Indonesia), and the Caribbean depend economically on tropical climate tourism. Average temperatures of 28–30°C year-round, clear warm seas, and coral reefs attract millions of visitors. However, rising sea levels from climate change threaten low-lying tropical islands — the Maldives, with an average elevation of just 1.5 m, may become uninhabitable within decades.
Where do you see this in real life? Think about where chocolate, bananas, coffee, and rubber come from — all are tropical crops that can only grow in the hot, wet conditions found near the equator. Every time you eat a banana, you are experiencing the tropical climate zone.
Practice Problems
Why do tropical areas near the equator have high temperatures all year round?
Show answer
Why does a tropical rainforest climate have heavy rainfall throughout the year?