Climates

Climate refers to the long-term patterns of temperature, humidity, wind, precipitation, and other atmospheric variables in a region. It describes averages and variability over long periods, typically 30 years or more. Weather, by contrast, denotes short-term conditions.

The climate system involves the atmosphere, hydrosphere, cryosphere, biosphere, and lithosphere. Primary drivers include latitude and the amount of solar radiation received, elevation, proximity to oceans and large lakes, ocean currents, prevailing winds, and topography. These factors interact to create regional climate patterns such as seasonality, rainfall distribution, and extremes in temperature or moisture.

Climate zones are commonly described using classification schemes such as the Köppen climate classification, which groups regions into tropical, arid, temperate, cold (continental), and polar types, with further subdivisions. Such classifications aid in comparing environments, guiding agricultural practices, water management, and biodiversity studies.

Climates exhibit natural variability on seasonal, annual, and decadal timescales due to phenomena like El Niño–Southern Oscillation, monsoons, volcanic activity, and Arctic or Antarctic oscillations. Human activities, notably greenhouse gas emissions and changes in land use, are altering long-term averages in many regions and can shift the frequency and intensity of extreme events.

Climate data are gathered from weather stations, ships, buoys, satellites, and paleoclimate proxies. Global climate models simulate past and future climates under different emissions scenarios, providing projections that support policy, planning, and risk assessment.