The statistical properties of atmospheric and related oceanic conditions over an extended period, including means, variability and extremes. Radiation budgets, ocean circulation and atmospheric transport help determine its large-scale structure.
Climate variability is variation in climate statistics across time or space, including fluctuations in means, seasonal behavior and extremes. It can arise internally from interacting atmospheric and oceanic dynamics or from changing external influences. The averaging interval and variable being measured must be specified.
A climate system can fluctuate even under steady forcing. A nonlinear convection model can produce nonperiodic behavior without a random external input, illustrating one mechanism for internally generated variability. This does not identify the cause of a particular observed climate trend: attribution requires comparing mechanisms, timescales and independent observations.[ref]
Deterministic Nonperiodic Flow by Edward Norton Lorenz. 1963 deterministic convection model and nonperiodic trajectories
The climate of an earlier geological interval, inferred from dated geological, geochemical or biological indicators. Spatially coherent glacial deposits, striations and climate-sensitive rocks can test a continental reconstruction, provided their ages and original tectonic contexts are established.
A rain shadow is a region with reduced precipitation downwind of a topographic barrier. Air forced up a mountain expands and cools. If it reaches saturation, condensation and precipitation can remove some of its water vapour on the windward side.
Air descending on the other side is compressed and warms, lowering its relative humidity when its water-vapour content changes little. This favours a drier leeward region. The effect depends on the wind direction, moisture supply and storm structure: a mountain range does not permanently prevent every possible route by which moist air can reach its far side.
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Climate refers to the long-term patterns and averages of weather conditions in a particular region over an extended period, typically decades to millions of years. It encompasses various elements such as temperature, humidity, precipitation, wind patterns, and the presence of weather phenomena. Unlike weather, which describes short-term atmospheric conditions, climate provides a broader perspective on what one can generally expect in a given area throughout the seasons and years.