Satellite image indicating ocean temperatures

The American writer Mark Twain is credited with saying, "climate is what we expect, weather is what we get." Climate is, generally speaking, the "average" weather trend over long time periods.

Natural processes have changed the Earth's climate dramatically over the last 4.6 billion years. Volcanoes, the energy output of the Sun, the tilt and orbit of the planet relative to the Sun, and the movement of the continents are some of the factors that influence the climate.

Human activities such as burning coal and driving automobiles add greenhouse gases to the ones naturally present in the atmosphere and potentially warm the atmosphere more than normal. Scientists are currently trying to predict the extent of this manmade climate change. Visit BBC Weather to learn more about climate science.

Image: A satellite image indicating Pacific Ocean water temperatures associated with El Niño, a periodic climate pattern. (credit: NASA/JPL)


Satellite image indicating ocean temperatures Climate

TV clips (6)


Climate is the statistics of weather, usually over a 30-year interval. It is measured by assessing the patterns of variation in temperature, humidity, atmospheric pressure, wind, precipitation, atmospheric particle count and other meteorological variables in a given region over long periods of time. Climate differs from weather, in that weather only describes the short-term conditions of these variables in a given region.

A region's climate is generated by the climate system, which has five components: atmosphere, hydrosphere, cryosphere, lithosphere, and biosphere.

The climate of a location is affected by its latitude, terrain, and altitude, as well as nearby water bodies and their currents. Climates can be classified according to the average and the typical ranges of different variables, most commonly temperature and precipitation. The most commonly used classification scheme was the Köppen climate classification. The Thornthwaite system, in use since 1948, incorporates evapotranspiration along with temperature and precipitation information and is used in studying biological diversity and how climate change effects it. The Bergeron and Spatial Synoptic Classification systems focus on the origin of air masses that define the climate of a region.

Paleoclimatology is the study of ancient climates. Since direct observations of climate are not available before the 19th century, paleoclimates are inferred from proxy variables that include non-biotic evidence such as sediments found in lake beds and ice cores, and biotic evidence such as tree rings and coral. Climate models are mathematical models of past, present and future climates. Climate change may occur over long and short timescales from a variety of factors; recent warming is discussed in global warming. Global warming results in redistributions. For example, "a 3°C change in mean annual temperature corresponds to a shift in isotherms of approximately 300–400 km in latitude (in the temperate zone) or 500 m in elevation. Therefore, species are expected to move upwards in elevation or towards the poles in latitude in response to shifting climate zones".

Read more at Wikipedia

This entry is from Wikipedia, the user-contributed encyclopedia. If you find the content in the 'About' section factually incorrect, defamatory or highly offensive you can edit this article at Wikipedia.

Other related BBC topics