Climat

Climat is the long-term pattern of weather that characterizes a region, typically described by statistical properties of the atmosphere over extended periods. In English-language contexts the term is climate; climat is the equivalent term in French and is used in many multilingual studies to refer to the same concept. The climate of a place encompasses typical temperatures, precipitation, humidity, winds, and the seasonal and diurnal cycles that recur over decades.

A climate system is determined by interactions among the atmosphere, hydrosphere, cryosphere, biosphere, and lithosphere. Its key features include mean conditions, variability, seasonality, and the frequency and intensity of extremes such as heatwaves, droughts, heavy rainfall, and frosts. Climate normals—usually 30-year averages—are used to describe typical conditions and to identify departures from the norm. Climate classifications, such as the Köppen system, organize regions by dominant temperature and precipitation regimes.

Data and methods for studying climat rely on instrumental records, reanalysis products, and palaeoclimate proxies to extend observations further back in time. Climate understanding combines observations with models that simulate physical processes to project future conditions under different forcing scenarios.

Drivers of climate include natural factors (variations in solar radiation, volcanic activity, and internal climate cycles) and human activities (greenhouse gas emissions, land-use change, and aerosol emissions). These drivers shape climate change, involving shifts in average conditions as well as changes in variability and extremes.

Applications of climate knowledge inform water resource management, agriculture, infrastructure planning, and policy. Adaptation and mitigation efforts address risks posed by changing climate patterns, while ongoing research aims to reduce uncertainties in projections and improve climate services.