Harmattan
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TheHarmattanis aseasoninWest Africathat occurs between the end of November and the middle of March. It is characterized by the dry and dusty northeasterlytrade wind,of the same name, which blows from theSaharaover West Africa into theGulf of Guinea.[1]The name is related to the wordharamatain theTwilanguage.[2]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.[3]
The Harmattan blows during the dry season, which occurs during the months with the lowest sun. In this season, thesubtropical ridgeofhigh pressurestays over the central Sahara and the low-pressureIntertropical 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
[edit]This season differs fromwinterbecause it is characterized by cold, dry,[4]dust-laden wind, and also wide fluctuations in theambient temperaturesof the day and night. Temperatures can easily be as low as 9 °C (48 °F) all day, but sometimes in the afternoon the temperature can also soar to as high as 30 °C (86 °F), while therelative humiditydrops under 5%. It can also be hot in some regions, like in the Sahara.[5]
The air is particularly dry and desiccating when the Harmattan blows over the region.[4]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 indust stormsorsandstorms.[citation needed]The wind can increase fire risk[6]and cause severe crop damage.[7]The interaction of the Harmattan withmonsoonwinds can causetornadoes.[1]
Harmattan haze
[edit]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,[8]comparable to a heavyfog.This effect is known as the Harmattan haze. It costs airlines millions of dollars in cancelled and diverted flights each year.[9][10]When the haze is weak, the skies are clear.[11]The extreme dryness of the air may cause branches of trees to die.[12]
Health
[edit]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.[13]
Humidity can drop lower than 15%, which can result in spontaneous nosebleeds for some people.[7]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 ofasthma.[14]
See also
[edit]References
[edit]- ^ab"Harmattan".Encyclopædia Britannica.Retrieved22 July2015.
- ^"Harmattan".Merriam-Webster.2012.
- ^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."
- ^abMinka, Ndazo Salka; Ayo, Joseph (2014)."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".Open Access Animal Physiology:1.doi:10.2147/OAAP.S51741.
- ^Sivakumar, Mannava V. K.; Ndiang'ui, Ndegwa, eds. (2007).Climate and Land Degradation.Environmental Science and Engineering.doi:10.1007/978-3-540-72438-4.ISBN978-3540724377.
At the southern fringe of the Sahara Desert, a special dry and hot wind, locally termed Harmattan, occurs.
- ^Oladipupo, Akolade R (13 December 2014)."Harmattan: Behold A Season".Leadership.Archived fromthe originalon 12 February 2015.
- ^abTerazono, Emiko; Blas, Javier (19 January 2012)."Saharan wind stirs cocoa market".Financial Times.Retrieved28 January2012.
- ^"Tuareg unrest".Temoust.BBC News. 7 September 2007. Archived fromthe originalon 30 December 2007.Retrieved8 October2007.
- ^Eze, Chinedu (15 January 2013)."Nigerian Civil Aviation warns pilots, airlines of Harmattan haze".This Day– via All Africa.
- ^Valdmanis, Richard (8 February 2012)."Giant dust cloud chokes west Africa".Reuters. Archived fromthe originalon 11 February 2012.Retrieved9 February2012.
- ^Akinrefon, Dapo (16 December 2014)."As harmattan finally hits Lagos".Vanguard.Retrieved11 October2015.
- ^"Arago on Comets".The North American Review.42(90). Boston: Charles Bowen: 213. January 1836.JSTOR25103785.
- ^Adhvaryu, Achyuta; Bharadwaj, Prashant; Fenske, James; Nyshadham, Anant; Stanley, Richard (18 March 2024). "Dust and Death: Evidence from the West African Harmattan".The Economic Journal.134(659): 885–912.doi:10.1093/ej/uead088.PMC10945368.PMID38505244.
- ^Anuforo, Emeka; Chukwu, Lilian (20 January 2015)."Coping With Health Hazards of Harmattan Haze".Rivers State News.
External links
[edit]- Chisholm, Hugh,ed. (1911)..Encyclopædia Britannica(11th ed.). Cambridge University Press.