You can read a climograph and you know the biomes. Now connect them: two numbers, yearly temperature and yearly precipitation, predict most biomes.
Key idea
Temperature and rainfall together decide the biome: hot and wet makes rainforest; hot with a long dry season, savanna; hot or cold and very dry, desert; cold with some rain, taiga; very cold, tundra.
Why it works
Warmth sets how long plants can grow; water sets how big they can get. Trees need plenty of water: with less, grasses replace them, and with even less, only desert plants survive. Cold shortens the growing season until only conifers, then only mosses and low shrubs, can live. The chart is simplified, after the ecologist Robert Whittaker (1975); real boundaries also depend on soil, fire and when in the year the rain falls.
Worked example: Hot and dry
A place averages 24 °C and gets 15 cm of rain a year. Which biome?
- 24 °C is hot.
- 15 cm is very little rain, under 25 cm.
Answer: Desert.
Worked example: From a climograph
A climograph shows 26 to 31 °C all year, with heavy rain in half the year and almost none in the other half. Which biome?
- Hot all year: tropical.
- A long dry season means trees are scattered and grass covers the ground.
Answer: Savanna.
Common mistake
Matching by temperature alone. A hot place with little rain is a desert, not a rainforest; a cold place with some rain can grow taiga, while a colder, drier one is tundra. Always read both: the line and the bars.