harmattan
{{Short description|West African dry weather season}}
{{For multi|the French publisher|L'Harmattan|the Maemo release code-named Harmattan|Maemo#Naming}}
{{use dmy dates|date=December 2023}}
File:MosqueinAbuja.jpg in Abuja]]
{{Weather}}
The Harmattan is a season in West Africa that occurs between the end of November and the middle of March. It is characterized by the dry and dusty northeasterly trade wind, of the same name, which blows from the Sahara over West Africa into the Gulf of Guinea.{{cite encyclopedia |url=http://www.britannica.com/science/harmattan |title=Harmattan |encyclopedia=Encyclopædia Britannica |access-date=22 July 2015 }} The name is related to the word {{lang|tw|haramata}} in the Twi language.{{cite dictionary |year=2012 |title=Harmattan |dictionary=Merriam-Webster |url=http://www.merriam-webster.com/dictionary/Harmattan }} The temperature is cold mostly at night in some places but can be very hot in certain places during daytime. Generally, temperature differences can also depend on local circumstances.Geographical Review (1919): "Knox writes of this wind : The Harmattan is experienced as a wind which blows, especially in the months of December, January, and February, from the NE. and is a hot wind in some localities and a cold wind in others, according to circumstances."
The Harmattan blows during the dry season, which occurs during the months with the lowest sun. In this season, the subtropical ridge of high pressure stays over the central Sahara and the low-pressure Intertropical Convergence Zone (ITCZ) stays over the Gulf of Guinea. On its passage over the Sahara, the Harmattan picks fine dust and sand particles (between 0.5 and 10 microns). It is also known as the "doctor wind", because of its invigorating dryness compared with humid tropical air.
Effects
This season differs from winter because it is characterized by cold, dry,{{Cite journal |doi = 10.2147/OAAP.S51741|title = Influence of cold–dry (harmattan) season on colonic temperature and the development of pulmonary hypertension in broiler chickens, and the modulating effect of ascorbic acid|journal = Open Access Animal Physiology|pages = 1|year = 2014|last1 = Minka|first1 = Ndazo Salka|last2 = Ayo|first2 = Joseph|doi-access = free}} dust-laden wind, and also wide fluctuations in the ambient temperatures of the day and night. Temperatures can easily be as low as {{convert|9|C}} all day, but sometimes in the afternoon the temperature can also soar to as high as {{convert|35|C}}, while the relative humidity drops under 5%. It can also be hot in some regions, like in the Sahara.{{cite book |editor-first1=Mannava V. K. |editor-last1=Sivakumar |editor-first2=Ndegwa |editor-last2=Ndiang'ui|title=Climate and Land Degradation |series=Environmental Science and Engineering |isbn=978-3540724377 |doi=10.1007/978-3-540-72438-4 |year=2007 |quote=At the southern fringe of the Sahara Desert, a special dry and hot wind, locally termed Harmattan, occurs.}}
{{Multiple image
| image1 = Ho, Ghana.JPG
| image2 = Harmattan in Abuja.png
| caption2 = Before and after comparison of harmattan in Abuja (2004)
| direction = vertical
| caption1 = Harmattan haze over Ho, Ghana
| total_width = 270
}}
The air is particularly dry and desiccating when the Harmattan blows over the region. The Harmattan brings desert-like weather conditions: it lowers the humidity, dissipates cloud cover, prevents rainfall formation and sometimes creates big clouds of dust which can result in dust storms or sandstorms.{{citation needed|date=December 2014}} The wind can increase fire risk{{cite news |last=Oladipupo |first=Akolade R |title=Harmattan: Behold A Season |url=http://leadership.ng/entertainment/394904/harmattan-behold-season|newspaper=Leadership |date=13 December 2014 |archive-url=https://web.archive.org/web/20150212074606/http://leadership.ng/entertainment/394904/harmattan-behold-season |archive-date=2015-02-12}} and cause severe crop damage.{{cite news | url=http://www.ft.com/cms/s/0/b681e5f0-42b7-11e1-b756-00144feab49a.html#axzz1kkb8Prrr | title=Saharan wind stirs cocoa market | work=Financial Times | date=19 January 2012 | access-date=28 January 2012 |author1=Terazono, Emiko |author2=Blas, Javier}} The interaction of the Harmattan with monsoon winds can cause tornadoes.
=Harmattan haze=
In some countries in West Africa, the heavy amount of dust in the air can severely limit visibility and block the sun for several days,{{cite web |url= http://www.temoust.org/spip.php?article3206|title=Tuareg unrest |date=7 September 2007|access-date=8 October 2007 |work=Temoust |agency=BBC News |archive-url = https://web.archive.org/web/20071230031550/http://www.temoust.org/spip.php?article3206 |archive-date = 30 December 2007}} comparable to a heavy fog. This effect is known as the Harmattan haze. It costs airlines millions of dollars in cancelled and diverted flights each year.{{cite news |last=Eze |first=Chinedu |date=15 January 2013 |url=http://allafrica.com/stories/201301150511.html |title=Nigerian Civil Aviation warns pilots, airlines of Harmattan haze |newspaper=This Day |via=All Africa}}{{cite web |url=https://af.reuters.com/article/topNews/idAFJOE81706Z20120208 |archive-url=https://web.archive.org/web/20120211063923/http://af.reuters.com/article/topNews/idAFJOE81706Z20120208 |url-status=dead |archive-date=11 February 2012 |title=Giant dust cloud chokes west Africa |last=Valdmanis |first=Richard |date=8 February 2012 |publisher=Reuters |access-date=9 February 2012}} When the haze is weak, the skies are clear.{{cite web | url=http://www.vanguardngr.com/2014/12/harmattan-finally-hits-lagos/ | title=As harmattan finally hits Lagos |first=Dapo |last=Akinrefon| website=Vanguard | date=16 December 2014 | access-date=11 October 2015}} The extreme dryness of the air may cause branches of trees to die.{{cite journal |title=Arago on Comets |url=https://books.google.com/books?id=aqNKAAAAcAAJ&pg=PA213 |journal=The North American Review |volume=42|issue=90 |location=Boston |publisher=Charles Bowen |page=213 |date=January 1836 |jstor=25103785 |jstor-access=free}}
=Health=
A 2024 study found that dust carried by the Harmattan increases infant and child mortality, as well as has persistent adverse health impacts on surviving children.{{cite journal |last1=Adhvaryu |first1=Achyuta |last2=Bharadwaj |first2=Prashant |last3=Fenske |first3=James |last4=Nyshadham |first4=Anant |last5=Stanley |first5=Richard |title=Dust and Death: Evidence from the West African Harmattan |journal=The Economic Journal |date=18 March 2024 |volume=134 |issue=659 |pages=885–912 |doi=10.1093/ej/uead088|pmid=38505244 |pmc=10945368 }}
Humidity can drop lower than 15%, which can result in spontaneous nosebleeds for some people. Other health effects on humans may include conditions of the skin (dryness of the skin), dried or chapped lips, eyes, and respiratory system, including aggravation of asthma.{{cite news|last1=Anuforo|first1=Emeka|last2=Chukwu|first2=Lilian|title=Coping With Health Hazards of Harmattan Haze|url=http://www.riversstatenews.com/coping-with-health-hazards-of-harmattan-haze/|work=Rivers State News|date=20 January 2015}}
See also
References
{{Reflist|30em}}