Editing Climatology (section)

== Topics of research ==
Topics that climatologists study comprise three main categories: [[climate variability]], mechanisms of climatic change, and modern changes of climate.<ref>{{Cite web|url=https://www.thoughtco.com/what-is-climatology-3443689|title=How Climatology Is Different From Meteorology|last1=Oblack|first1=Rachelle|last2=McDougal|first2=Holt|date=3 July 2019|website=ThoughtCo|language=en|access-date=23 October 2019|last3=weather.|archive-date=23 October 2019|archive-url=https://web.archive.org/web/20191023121347/https://www.thoughtco.com/what-is-climatology-3443689|url-status=live}}</ref>

=== Climatological processes ===
Various factors affect the average state of the atmosphere at a particular location. For instance, midlatitudes will have a pronounced [[Season|seasonal cycle]] of temperature whereas [[Tropics|tropical regions]] show little variation of temperature over a year.{{Sfn|Rohli|Vega|2018|p=25}} Another major variable of climate is continentality: the distance to major water bodies such as [[ocean]]s. Oceans act as a moderating factor, so that land close to it has typically less difference of temperature between [[winter]] and summer than areas further from it.{{Sfn|Rohli|Vega|2018|p=}} The atmosphere interacts with other parts of the [[climate system]], with winds generating [[ocean current]]s that transport heat around the globe.{{Sfn|Rohli|Vega|2018|p=54}}

=== Climate classification ===
Classification is an important method of simplifying complicated processes. Different [[climate classification]]s have been developed over the centuries, with the first ones in [[Ancient Greece]]. How climates are classified depends on what the application is. A [[Wind power|wind energy]] producer will require different information (wind) in a classification than someone more interested in agriculture, for whom precipitation and temperature are more important.{{Sfn|Rohli|Vega|2018|p=159}} The most widely used classification, the [[Köppen climate classification]], was developed during the late nineteenth century and is based on vegetation. It uses monthly data concerning temperature and [[precipitation]].{{Sfn|Rohli|Vega|2018|p=160}}

=== Climate variability ===
There are different types of variability: recurring patterns of temperature or other climate variables. They are quantified with different indices. Much in the way the [[Dow Jones Industrial Average]], which is based on the stock prices of 30 companies, is used to represent the fluctuations of stock prices in general, climate indices are used to represent the essential elements of climate. Climate indices are generally devised with the twin objectives of simplicity and completeness, and each index typically represents the status and timing of the climate factor it represents. By their very nature, indices are simple, and combine many details into a generalized, overall description of the atmosphere or ocean which can be used to characterize the factors which effect the global climate system.

[[El Niño–Southern Oscillation]] (ENSO) is a coupled ocean-atmosphere phenomenon in the Pacific Ocean responsible for much of the global variability of temperature,{{Sfn|Rohli|Vega|2018|p=54}} and has a cycle between two and seven years.<ref>{{cite web|url=http://www.cpc.noaa.gov/products/analysis_monitoring/ensostuff/ensofaq.shtml#HOWOFTEN|title=ENSO FAQ: How often do El Niño and La Niña typically occur?|access-date=26 July 2009|date=19 December 2005|author=Climate Prediction Center|publisher=[[National Centers for Environmental Prediction]]|archive-url=https://web.archive.org/web/20090827143632/http://www.cpc.noaa.gov/products/analysis_monitoring/ensostuff/ensofaq.shtml#HOWOFTEN|archive-date=27 August 2009|url-status=dead|author-link=Climate Prediction Center}}</ref> The [[North Atlantic oscillation]] is a mode of variability that is mainly contained to the lower atmosphere, the [[troposphere]]. The layer of atmosphere above, the [[stratosphere]] is also capable of creating its own variability, most importantly the [[Madden–Julian oscillation]] (MJO), which has a cycle of approximately 30 to 60 days. The [[Interdecadal Pacific oscillation]] can create changes in the Pacific Ocean and lower atmosphere on decadal time scales.

=== Climate change ===
Climate change occurs when changes of Earth's [[climate system]] result in new [[weather]] patterns that remain for an extended period of time. This duration of time can be as brief as a few decades to as long as millions of years. The climate system receives nearly all of its energy from the sun. The climate system also gives off energy to [[outer space]]. The balance of incoming and outgoing energy, and the passage of the energy through the climate system, determines [[Earth's energy budget]]. When the incoming energy is greater than the outgoing energy, earth's energy budget is positive and the climate system is warming. If more energy goes out, the energy budget is negative and earth experiences cooling.<ref name="WEB-NASA-EnergyBalance">{{Cite web |url=https://earthobservatory.nasa.gov/features/EnergyBalance |title=Climate and Earth's Energy Budget |date=14 January 2009 |website=earthobservatory.nasa.gov |language=en |access-date=3 December 2021 |archive-date=2 October 2019 |archive-url=https://web.archive.org/web/20191002090444/https://earthobservatory.nasa.gov/features/EnergyBalance |url-status=live }}</ref>  Climate change also influences the average [[sea level]].

[[Modern climate change]] is caused largely by the human emissions of [[greenhouse gas]] from the burning of fossil fuel which increases [[Surface air temperature|global mean surface temperatures]]. Increasing temperature is only one aspect of modern climate change, which also includes observed changes of [[precipitation]], [[storm track]]s and cloudiness. Warmer temperatures are causing further changes of the [[climate system]], such as the [[Retreat of glaciers since 1850|widespread melt of glaciers]], [[sea level rise]] and shifts of flora and fauna.<ref>{{Cite web|url=https://www.nationalgeographic.com/environment/global-warming/global-warming-effects/|title=Global Warming Effects|date=14 January 2019|website=National Geographic|language=en|access-date=2 January 2020|archive-date=2 December 2019|archive-url=https://web.archive.org/web/20191202114510/https://www.nationalgeographic.com/environment/global-warming/global-warming-effects/|url-status=dead}}</ref>