Editing Tropics (section)

== Seasons and climate ==
[[File:Bora Bora.jpg|thumb|Aerial view of [[Bora Bora]] in [[French Polynesia]]]]
[[File:Kota Kinabalu by Dale Preston.jpg|thumb|Tropical sunset over the sea in [[Kota Kinabalu]] in [[Malaysia]]]]

Many tropical areas have both a dry and a wet season. The [[wet season]], rainy season or green season is the time of year, ranging from one or more months when most of the average annual [[rainfall]] in a region falls.<ref>Glossary of Meteorology (2009). [http://amsglossary.allenpress.com/glossary/search?id=rainy-season1 Rainy season.] {{webarchive|url=https://web.archive.org/web/20090215203023/http://amsglossary.allenpress.com/glossary/search?id=rainy-season1 |date=2009-02-15 }} American Meteorological Society. Retrieved on 2008-12-27.</ref>  Areas with wet seasons are disseminated across portions of the tropics and [[subtropics]], some even in [[Temperate climate|temperate]] regions.<ref>Michael Pidwirny (2008). [http://www.physicalgeography.net/fundamentals/9k.html CHAPTER 9: Introduction to the Biosphere.] PhysicalGeography.net. Retrieved on 2008-12-27.</ref>  Under the [[Köppen climate classification]], for [[tropical climate]]s, a wet-season month is defined as one or more months where average precipitation is {{convert|60|mm|sp=us|abbr=on}} or more.<ref>{{cite web | url=http://www.hydrol-earth-syst-sci.net/11/1633/2007/hess-11-1633-2007.pdf | title=Updated world Koppen-Geiger climate classification map | archive-url=https://web.archive.org/web/20071024063821/http://www.hydrol-earth-syst-sci.net/11/1633/2007/hess-11-1633-2007.pdf | archive-date=2007-10-24 | url-status=dead }}</ref>  Some areas with pronounced rainy seasons see a break in rainfall during mid-season when the [[Intertropical Convergence Zone]] or [[monsoon trough]] moves poleward of their location during the middle of the warm season;<ref name="JS">J . S. 0guntoyinbo and F. 0. Akintola (1983). [http://www.cig.ensmp.fr/~iahs/redbooks/a140/iahs_140_0063.pdf Rainstorm characteristics affecting water availability for agriculture.] {{webarchive|url=https://web.archive.org/web/20090205200119/http://www.cig.ensmp.fr/~iahs/redbooks/a140/iahs_140_0063.pdf |date=2009-02-05 }} IAHS Publication Number 140. Retrieved on 2008-12-27</ref> Typical vegetation in these areas ranges from moist [[seasonal tropical forest]]s to [[savanna]]hs.[[File:Monthly zonal mean precipitation.png|thumb|Graph showing the zonally averaged monthly precipitation. The tropics receive more precipitation than higher latitudes. The precipitation maximum, which follows the solar equator through the year, is under the rising branch of the Hadley circulation. The sub-tropical minima are under the descending branch and cause the formation of desert areas.]]When the wet season occurs during the warm season, or [[summer]], [[precipitation (meteorology)|precipitation]] falls mainly during the late afternoon and early evening hours. The wet season is a time when [[air quality]] improves, freshwater quality improves and vegetation grows significantly due to the wet season supplementing flora, leading to crop yields late in the season. Floods and rains cause rivers to overflow their banks, and some animals to retreat to higher ground. [[Soil]] nutrients are washed away and erosion increases. The incidence of [[malaria]] increases in areas where the rainy season coincides with high temperatures.  Animals have adaptation and survival strategies for the wetter regime. The previous dry season leads to food shortages into the wet season, as the crops have yet to mature.

However, regions within the tropics may well not have a tropical climate. Under the Köppen climate classification, much of the area within the geographical tropics is classed not as "tropical" but as "dry" ([[desert climate|arid]] or [[semi-arid climate|semi-arid]]), including the [[Sahara|Sahara Desert]], the [[Atacama Desert]] and [[Australian Outback]]. Also, there are [[alpine tundra]] and snow-capped peaks, including [[Mauna Kea]], [[Mount Kilimanjaro]], [[Puncak Jaya]] and the [[Andes]] as far south as the northernmost parts of [[Chile]] and [[Peru]].

=== Climate change ===
{{See also|Climate change effects on tropical regions}}

The climate is changing in the tropics, as it is in the rest of the world.<ref>{{Cite book |date=2014-03-24 |editor-last=Intergovernmental Panel on Climate Change |title=Climate Change 2013 – The Physical Science Basis |url=http://dx.doi.org/10.1017/cbo9781107415324 |doi=10.1017/cbo9781107415324|isbn=978-1-107-05799-9 }}</ref> The effects of steadily rising concentrations of [[greenhouse gas]]es on the climate may be less obvious to tropical residents, however, because they are overlain by considerable natural variability. Much of this variability is driven by the [[El Niño–Southern Oscillation|El Niño-Southern Oscillation (ENSO)]]. The Tropics has warmed by 0.7–0.8&nbsp;°C over the last century—only slightly less than the global average—but a strong [[El Niño]] made 1998 the warmest year in most areas, with no significant warming since. Climate models predict a further 1–2&nbsp;°C warming by 2050 and 1–4&nbsp;°C by 2100.