While weather conditions often change rapidly, climate — the average weather conditions of an area — remains stable over long periods of time. Many different climates exist on Earth, each with particular characteristics. For example, some areas of the world are hot and rainy year-round, while other locations are freezing cold with barely any precipitation. Different geographic locations exhibit different average weather conditions, dividing the world into regions with distinctive climates.

Scientists classify Earth's climates in a variety of ways. One of the most widely used classification systems — developed by a German climatologist named Wladimir Koppen — classifies climates into five main groups: tropical, dry, temperate, continental, and polar. These groups are further divided into subtypes with more specific characteristics. Other climate classification systems are similar, using monthly and annual averages of temperature and precipitation to differentiate between climate zones. This resource highlights ten climate zones: tropical wet, tropical dry, humid subtropical, humid continental, marine west coast, highland, semiarid, desert, tundra, and ice cap.

The latitude of an area plays a major role in determining climate. Because of the tilt of Earth's axis, the angle at which the Sun's rays hit Earth throughout the year varies significantly for different latitudes — so a region's proximity to the equator or the poles greatly impacts its climate. Other influential factors are topography, elevation, ocean currents, and wind patterns. Looking at the distribution of climate zones around the world, it is possible to see trends in the location of climate types.

Distinct communities of plants and animals living together under the same environmental conditions are grouped into categories called biomes. The most common types of plants growing in an area reflect the area's climate and are typically used to define the biome.

An astounding variety of plant and animal life is distributed around the planet in distinct patterns. Because plant and animal life are closely tied to climate conditions, if you travel from one continent to another, change latitude by 10 or 20 degrees, or ascend or descend a mere 1,000 meters (3280 feet) in elevation, you're likely to encounter groups of plants and animals that are dramatically different from those living where your journey began. Over time, species become increasingly adapted to their environments, and therefore become increasingly different from species in other types of environments.

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