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The climate is the weather averaged over a long period of time. A descriptive saying is that "climate is what you expect, weather is what you get". The IPCC glossary definition is:- Climate in a narrow sense is usually defined as the “average weather”, or more rigorously, as the statistical description in terms of the mean and variability of relevant quantities over a period of time ranging from months to thousands or millions of years. The classical period is 30 years, as defined by the World Meteorological Organization (WMO). These quantities are most often surface variables such as temperature, precipitation, and wind. Climate in a wider sense is the state, including a statistical description, of the climate system.[1]
The exact boundaries of what is climate and what is weather are not well defined and depend on the application. For example, in some senses an individual El Niño event could be considered climate; in others, as weather.
When the original conception of climate as a long-term average came to be considered, perhaps towards the end of the 19th century, the idea of climate change was not current, and a 30 year average seemed reasonable (but see note 1). Nowadays, knowing that there are long-term trends in the temperature record, it is harder to give a precise contradiction-free definition of climate: over a 30 year period, averages may shift; over a shorter period, the statistics are less stable.
In a given geographical region, the climate generally does not vary over time on the scale of a human life span. However, over geological time, climate can vary considerably for a given place on the earth. For example, Scandinavia has been through a number of Ice ages over hundreds of thousands of years (the last one ending about 10,000 years ago). Paleoclimatology is the study of these past climates.
1 Classifications
In the original sense, climate is a concept used to divide the world into regions sharing similar climatic parameters. Climate regions can be classified on the basis of temperature and precipitation alone. Examples of such climate schemes are the Köppen climate classification or the Thornthwaite climate classification schemes.
For more details about specific climates, please see:
- Tropical climate
- Subtropical climate
- Mediterranean climate
- Temperate climate
- Oceanic climate
- Continental climate
- Alpine climate
- Subarctic climateRegions with subarctic climate are characterized by very cold winters, and brief, often warm, summers. This kind of climate offers some of the most extreme seasonal temperature variations found on the planet: In winter, temperature can drop to -40° Celsiu
- Polar climateRegions with polar climate are characterized by being the coldest places on earth, situated on the outer side of the (ant) arctic circles. Places with polar climates are often covered in glaciers or a permanent or semi-permanent layer of ice. The only con
- Climate of AntarcticaThe climate of Antarctica is cold and dry. Antarctica is the coldest place on earth. The lowest temperature ever recorded on earth was -89. 4 °C (-129 °F) recorded in 1983 at Vostok Station. The highest temperature ever recorded in Antarctica was 14.
- Arid climate
To understand a climate of a specific place or area, please see the article on that place or area.
2 See also
- Climate changeThe term climate change is used to refer to changes in the Earth's climate. In the most general sense, it can be taken to mean changes over all timescales and in all of the components of climate, including precipitation and clouds as well as temperature.
- Solar variationSolar variation refers to fluctuation in the amount of energy emitted by the Sun. Small variations have been measured from satellites during recent decades. Of interest to climate scientists is whether these variations have a significant effect on the tem.
