Climate regions are classified in three ways, according to the University of Wisconsin. Empirical classification systems are based on observable climate characteristics, such as temperature and precipitation. Genetic classification systems are based on the causes of climate, such as pressure systems, air masses and solar radiation. Scientists, however, do not have a complete understanding of what causes climatic differences. Researchers developed applied classification systems in response to particular climate problems. One of the most commonly used climate classification systems is the Koppen system, which classifies climates into five major types: tropical, dry, warm temperate, subarctic and polar. Average temperature and precipitation determine the classifications within the Koppen system.
Tropical climates are concentrated around the equator, rarely reaching beyond 25 degrees of latitude. In these areas, average temperatures always exceed 18 degrees Celsius and rainfall exceeds 1,500 millimeters (59 inches). Localized conditions, such as altitude, can affect a region’s climate. The Koppen classification system uses subcategories to account for these minor differences. Tropical climates can be categorized as wet, monsoon, or wet and dry. Indonesia, for example, has a tropical climate.
A climate is categorized as dry if precipitation is exceeded by transpiration and potential evaporation. This climate is typically found between 20 and 35 degrees north and south of the equator. Northern Africa has a dry climate. Dry climates include deserts, which cover 12 percent of the land on Earth, and grasslands, which cover 14 percent of the land on Earth.
Warm temperate climates have warm summers and mild winters. These regions are typically located between 30 and 50 degrees of latitude on the borders of most continents. The southeastern United States has a warm temperate climate. Thunderstorms occur often during the summer months in this climate. Most moisture during the winter months is the result of midlatitude cyclones.
Regions that have subarctic climates are closer to the poles than regions with warm temperate climates. Russia has a subarctic climate. Summers in these regions can be warm but are typically cool. Average temperatures for the warmest month of the year are over 10 degrees Celsius. Winters in subarctic climates are cold, with an average temperature in the coldest month of less than minus 3 degrees Celsius. Snowstorms and strong winds are typical during the winter in this climate.
Polar climates are cold all year. The temperature rarely rises above 10 degrees Celsius. Greenland and Antarctica have polar climates. This climate is also found on the northern coasts of Europe, Asia, and North America. In some regions, the soil is permanently frozen; this is known as permafrost. In other areas, the land is permanently covered in ice and snow. Climate conditions affect the wildlife and vegetation that can be found in a particular region. Mosses, lichen and small, woody shrubs dominate polar climates.
- Nick White/Photodisc/Getty Images