Harmattan

Last updated

Harmattan haze surrounding Abuja National Mosque in Abuja MosqueinAbuja.jpg
Harmattan haze surrounding Abuja National Mosque in Abuja

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. [1] The name is related to the word haramata in the Twi language. [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]

Contents

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, [4] dust-laden wind, and also wide fluctuations in the ambient temperatures of 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 35 °C (95 °F), while the relative humidity drops under 5%. It can also be hot in some regions, like in the Sahara. [5]

Ho, Ghana.JPG
Harmattan haze over Ho, Ghana
Harmattan in Abuja.png
Before and after comparison of harmattan in Abuja (2004)

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 in dust storms or sandstorms.[ citation needed ] The wind can increase fire risk [6] and cause severe crop damage. [7] The interaction of the Harmattan with monsoon winds can cause tornadoes. [1]

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, [8] 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. [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

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 of asthma. [14]

See also

Related Research Articles

<span class="mw-page-title-main">Geography of Cape Verde</span>

Cape Verde is a group of arid Atlantic islands which are home to distinct communities of plants, birds, and reptiles.

<span class="mw-page-title-main">Geography of Nigeria</span>

Nigeria is a country in West Africa. It shares land borders with the Republic of Benin to the west, Chad and Cameroon to the east, and Niger to the north. Its coast lies on the Gulf of Guinea in the south and it borders Lake Chad to the northeast. Notable geographical features in Nigeria include the Adamawa Plateau, Mambilla Plateau, Jos Plateau, Obudu Plateau, the Niger River, Benue River, and Niger Delta.

<span class="mw-page-title-main">Fog</span> Atmospheric phenomenon

Fog is a visible aerosol consisting of tiny water droplets or ice crystals suspended in the air at or near the Earth's surface. Fog can be considered a type of low-lying cloud usually resembling stratus and is heavily influenced by nearby bodies of water, topography, and wind conditions. In turn, fog affects many human activities, such as shipping, travel, and warfare.

<span class="mw-page-title-main">Dust storm</span> Meteorological phenomenon common in arid and semi-arid regions

A dust storm, also called a sandstorm, is a meteorological phenomenon common in arid and semi-arid regions. Dust storms arise when a gust front or other strong wind blows loose sand and dirt from a dry surface. Fine particles are transported by saltation and suspension, a process that moves soil from one place and deposits it in another.

<span class="mw-page-title-main">Santa Ana winds</span> California weather phenomenon

The Santa Ana winds, also sometimes called the devil winds, are strong, extremely dry downslope winds that originate inland and affect coastal Southern California and northern Baja California. They originate from cool, dry high-pressure air masses in the Great Basin.

<span class="mw-page-title-main">Desert climate</span> Arid climate subtype in the Köppen climate classification system with very little precipitation

The desert climate or arid climate is a dry climate sub-type in which there is a severe excess of evaporation over precipitation. The typically bald, rocky, or sandy surfaces in desert climates are dry and hold little moisture, quickly evaporating the already little rainfall they receive. Covering 14.2% of Earth's land area, hot deserts are the second-most common type of climate on Earth after the Polar climate.

<span class="mw-page-title-main">Air mass</span> Volume of air defined by its temperature and water vapor content

In meteorology, an air mass is a volume of air defined by its temperature and humidity. Air masses cover many hundreds or thousands of square miles, and adapt to the characteristics of the surface below them. They are classified according to latitude and their continental or maritime source regions. Colder air masses are termed polar or arctic, while warmer air masses are deemed tropical. Continental and superior air masses are dry, while maritime and monsoon air masses are moist. Weather fronts separate air masses with different density characteristics. Once an air mass moves away from its source region, underlying vegetation and water bodies can quickly modify its character. Classification schemes tackle an air mass's characteristics, as well as modification.

<span class="mw-page-title-main">Foehn wind</span> Type of dry down-slope wind occurring near mountains

A Foehn, or Föhn, is a type of dry, relatively warm downslope wind in the lee of a mountain range. It is a rain shadow wind that results from the subsequent adiabatic warming of air that has dropped most of its moisture on windward slopes. As a consequence of the different adiabatic lapse rates of moist and dry air, the air on the leeward slopes becomes warmer than equivalent elevations on the windward slopes.

<span class="mw-page-title-main">Trade winds</span> Equatorial east-to-west prevailing winds

The trade winds or easterlies are permanent east-to-west prevailing winds that flow in the Earth's equatorial region. The trade winds blow mainly from the northeast in the Northern Hemisphere and from the southeast in the Southern Hemisphere, strengthening during the winter and when the Arctic oscillation is in its warm phase. Trade winds have been used by captains of sailing ships to cross the world's oceans for centuries. They enabled European colonization of the Americas, and trade routes to become established across the Atlantic Ocean and the Pacific Ocean.

<span class="mw-page-title-main">Desert ecology</span> The study of interactions between both biotic and abiotic components of desert environments

Desert ecology is the study of interactions between both biotic and abiotic components of desert environments. A desert ecosystem is defined by interactions between organisms, the climate in which they live, and any other non-living influences on the habitat. Deserts are arid regions that are generally associated with warm temperatures; however, cold deserts also exist. Deserts can be found in every continent, with the largest deserts located in Antarctica, the Arctic, Northern Africa, and the Middle East.

<span class="mw-page-title-main">Loo (wind)</span> Hot, summer wind

The Loo is a strong, dusty, gusty, hot and dry summer wind from the west which blows over the Indo-Gangetic Plain region of North India and Pakistan. It is especially strong in the months of May and June. Due to its very high temperatures, exposure to it often leads to fatal heatstrokes.

<span class="mw-page-title-main">Saharan air layer</span> Hot, dry and sometimes dust-laden atmospheric layer

The Saharan air layer (SAL) is an extremely hot, dry, and sometimes dust-laden layer of the atmosphere that often overlies the cooler, more humid surface air of the Atlantic Ocean. It carries upwards of 60 million tons of dust annually over the ocean and the Americas. This annual phenomenon sometimes cools the ocean and suppresses Atlantic tropical cyclogenesis.

Delhi features a monsoon influenced humid subtropical climate bordering a hot semi-arid climate, with high variation between summer and winter temperatures and precipitation. Delhi's version of a humid subtropical climate is markedly different from many other humid subtropical cities such as São Paulo, Houston, and Brisbane in that the city features dust storms and wildfire haze due to its semi-arid climate.

<span class="mw-page-title-main">Climate of Albania</span>

Albania has a variety of climate systems. With its coastline facing the Adriatic and Ionian seas in the Mediterranean sea, its highlands backed upon the elevated Balkan landmass, and the entire country lying at a latitude subject to a variety of weather patterns during the winter and summer seasons, however it has a high number of climatic regions for such a small area. The coastal lowlands have typically mediterranean climate while the highlands have a continental climate. In both the lowlands and the interior, the weather varies markedly from north to south.

<span class="mw-page-title-main">Desert</span> Area of land where little precipitation occurs

A desert is a landscape where little precipitation occurs and, consequently, living conditions create unique biomes and ecosystems. The lack of vegetation exposes the unprotected surface of the ground to denudation. About one-third of the land surface of the Earth is arid or semi-arid. This includes much of the polar regions, where little precipitation occurs, and which are sometimes called polar deserts or "cold deserts". Deserts can be classified by the amount of precipitation that falls, by the temperature that prevails, by the causes of desertification or by their geographical location.

<span class="mw-page-title-main">Khamsin</span> Local name for a dry, hot wind in Egypt and the Levant

Khamsin, chamsin or hamsin, more commonly known in Egypt and Israel as khamaseen, is a dry, hot, sandy local wind affecting Egypt and the Levant; similar winds, blowing in other parts of North Africa, the Arabian Peninsula and the entire Mediterranean basin, have different local names, such as bad-i-sad-o-bist roz in Iran and Afghanistan, haboob in the Sudan, aajej in southern Morocco, ghibli in Tunis, harmattan in the western Maghreb, africo in Italy, sirocco which blows in winter over much of the Middle East, and simoom.

<span class="mw-page-title-main">Glossary of meteorology</span>

This glossary of meteorology is a list of terms and concepts relevant to meteorology and atmospheric science, their sub-disciplines, and related fields.

<span class="mw-page-title-main">Southeast Australian foehn</span> Weather event in Australia

The southeast Australian foehn is a westerly foehn wind and a rain shadow effect that usually occurs on the coastal plain of southern New South Wales, and as well as in southeastern Victoria and eastern Tasmania, on the leeward side of the Great Dividing Range.

<span class="mw-page-title-main">Climate of Nigeria</span> Climate zones in Nigeria

The climate of Nigeria is mostly tropical. Nigeria has three distinct climatic zones, two seasons, and an average temperature ranging between 21 °C and 35 °C. Two major elements determine the temperature in Nigeria: the altitude of the sun and the atmosphere's transparency. Its rainfall is mediated by three distinct conditions including convectional, frontal, and orographical determinants. Statistics from the World Bank Group showed Nigeria's annual temperature and rainfall variations, the nation's highest average annual mean temperature was 28.1 °C in 1938, while its wettest year was 1957 with an annual mean rainfall of 1,441.45mm.

References

  1. 1 2 "Harmattan". Encyclopædia Britannica . Retrieved 22 July 2015.
  2. "Harmattan". Merriam-Webster . 2012.
  3. 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."
  4. 1 2 Minka, 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 .
  5. 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. ISBN   978-3540724377. At the southern fringe of the Sahara Desert, a special dry and hot wind, locally termed Harmattan, occurs.
  6. Oladipupo, Akolade R (13 December 2014). "Harmattan: Behold A Season". Leadership. Archived from the original on 12 February 2015.
  7. 1 2 Terazono, Emiko; Blas, Javier (19 January 2012). "Saharan wind stirs cocoa market". Financial Times . Retrieved 28 January 2012.
  8. "Tuareg unrest". Temoust. BBC News. 7 September 2007. Archived from the original on 30 December 2007. Retrieved 8 October 2007.
  9. Eze, Chinedu (15 January 2013). "Nigerian Civil Aviation warns pilots, airlines of Harmattan haze". This Day via All Africa.
  10. Valdmanis, Richard (8 February 2012). "Giant dust cloud chokes west Africa". Reuters. Archived from the original on 11 February 2012. Retrieved 9 February 2012.
  11. Akinrefon, Dapo (16 December 2014). "As harmattan finally hits Lagos". Vanguard. Retrieved 11 October 2015.
  12. "Arago on Comets". The North American Review. 42 (90). Boston: Charles Bowen: 213. January 1836. JSTOR   25103785 .
  13. 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. PMC  10945368. PMID   38505244.
  14. Anuforo, Emeka; Chukwu, Lilian (20 January 2015). "Coping With Health Hazards of Harmattan Haze". Rivers State News.