Causes of wet and dry seasons in west africa

Average annual rainfall was 1,100 mm in 20072008 with less than 10% falling during the long dry season. Later wet seasons with more intense rainfall over africa. African savanna climate the savanna biome has a wetdry climate. The rainy season in west africa generally falls from the end of april july and again in septemberoctober. During the dry season, dry air flows out to sea and during the wet season, moist air flows inland from the sea, rises and produces rain. There are two main seasons the rainy season and the dry season. The tropical wet and dry climate is part of the climate classification system that groups climates based on vegetation. Areas with wet seasons are dispersed across portions of the tropics and subtropics. The cause of this climate is directly related to large bodies of water such as the mediterranean sea and ocean. There are actually two very different seasons in a savanna. The tropical climate is characterized by a wet season and a dry season.

Every year, the rainfilled monsoon winds cause the nearby bangali river to overflow its banks. Uganda has a springlike climate year round and has a less obvious wet and dry season. The term green season is also sometimes used as a euphemism by tourist authorities. The rainy season has several benefits to nigerians. Near these latitudes, there is one wet season and one dry season annually. This indicates a strengthening of the arabian heat low. The climate of nigeria, in west africa on the gulf of guinea, is tropical,and it tends to be hot all yearround. Jan 23, 2012 the local climate is coastalguinean with four seasons including a long dry season between november and march which is the hottest of the year with average monthly temperatures close to 28c. Often, the rainy season is the most scenic time to visit africas wild places, as it causes flowers to bloom and parched brush to turn green again.

In west africa, the northeast trades, in fact, blow offshore continent to sea from the sahara desert and reach the guinea coast as a dry, dustladen winds. However, depending on your destination, the dry season has its own drawbacks, ranging from intense heat to severe drought. Southern africa is particularly susceptible to climate variability and drought and is increasingly being threatened by desertification processes, degradation of land and water resources and loss of biodiversity. The a stands for a tropical climate, and the w for a dry season in the winter in the savanna climate there is a distinct dry season, which is in the winter. Examples of such animals are zebras, elephants, and wildebeest. Which of the following is an important cash cropnative to central america and south america that was introduced to west africa during the colonial period. Its highlands receive more rainfall than the lowlands, while the saharan regions receive the. Hot, dry continental air masses originating from the high pressure system above the sahara desert give rise to dusty harmattan winds over most of west africa from november to february. The characteristic four seasons of the continental united states give way in southernmost florida to only two seasons. Aboriginal people of this region recognise more than just two seasons.

Dry spells have been analyzed for durations of 23, 46, 715 and 1621 days similarly towhat was done by previous authors e. Vegetation, wildlife and human life are quite different from monsoon. Differences between anomalously wet and dry rainy seasons over the period 19612001 in equatorial east africa kenya, northern tanzania are studied at local scale using a 53 raingauge network and analysing six intraseasonal characteristics iscs. In many countries, the rainy season also coincides with the best time of year to see young animals and migrant. Factors contributing to urban malaria transmission in sub. West africa has been identified as a climatechange hotspot, with climate. Climate, climate change, the dry and wet seasons in west africa 2 on february 27, 20 12.

The climate observed is the result of the interactions between the ocean, the land and the atmosphere. Miami, for example, receives only about 26 percent of its average annual rain in a sixmonth period from november through april. Climate types for kids tropical wet and dry climate. Annual migration of tropical rain belt noaa climate. The wet season refers to the rains and many areas are closed to travel during the rains due to inaccessibility. Land in this area receives direct sunlight throughout most of the year. Rainfall decline over eastern africa linked to shorter wet. Although rainfed farming is a highrisk enterprise, it is also a way of life and people are committed to making the best of the scarce resources at their disposal. If it were not for the change in wind direction when the southeast trades have crossed the equator, the monsoon system of west africa could not be distinguished from the weather system, caused by the seasonal shift in the latitude of the intertropical convergence, as experienced over most of central africa. At december hot tropical summer comes to the republic of south africa. Semiarid climates bs often have a wet and dry season but it is not a defining factor. This climate is caused by changing wind and ocean currents.

Characteristics of wet and dry spells in west africa 127 rainy season is observed from june to september to thenorth. Changing wet and dry seasons may 30, 2017 extremes, precipitation ed hawkins the fickle nature of weather patterns is ultimately responsible for the where and when of tropical rainfall extremes which wreak damage on agriculture, infrastructure and people. Its highlands receive more rainfall than the lowlands, while the. In the savanna climate there is a distinct dry season, which is in the winter.

A delay in the wet season over west africa and the sahel of over 510 days on average, and later onset of the wet season over southern africa, is identified and associated with increasing strength of the saharan heat low in late boreal summer and a northward shift in the position of the tropical rain belt over augustdecember. The main characteristics of the west african seasons have been known to the scientific community for more than two centuries. The country is quite dry, with rainfall averages at around 464mm or less. Dry season brings on measles in subsaharan africa date. Monsoons are most often associated with the indian ocean. Situated in the southern hemisphere, christmas in south africa is a sunny, beachbound affair. Over land, the line is distorted because of the interaction between the tropical rain belt and monsoon circulations. The monsoon circulation occurs in parts of africa, asia, northern australia and arguably in the north america desert southwest debatable because it lacks a true seasonal flow reversal. Characteristics of wet and dry spells in the west african. The first benefit is that the fertile nigerian land, which needs the rain in other to grow food and other agricultural produce. Average daytime temperature is in the range between 26 c 79 f in cape town and 28 c 82 f in pretoria and durban. A monsoon is a seasonal change in the direction of the prevailing, or strongest, winds of a region. Jul, 2019 walker also found that asian monsoon seasons were often linked to drought in australia, indonesia, india, and parts of africa.

In summer, moist equatorial air masses originating over the atlantic ocean bring annual monsoon rains nicholson, 20. The most important consequence of this shifting is the annual alteration of. The tropical rain belt migrates north and south of the equator as the seasons change, leading to pronounced wet and dry seasons in many tropical countries. The southwest winter monsoon flows as a shallow humid layer of surface air less than 2,000 metres about 6,600 feet overlain by the primary northeast trade wind, which blows from the sahara and the sahel as a deep stream of. At the equator there are two wet and two dry seasons, as the rain belt passes over twice a year, once moving north and once moving south. Monsoonal climate seasons in the top end of the northern territory are generally known as the wet and the dry. When they do, the dry season occurs mostly during winter. Measles epidemics in niger fluctuate wildly from one season to another but the timing of the. Sep 22, 2017 others have scorching hot summers and windy, wet winters. Moreover, wet and dry spells are assessed for various duration categories. The rainy season occurs between april and october in the south while in the north, the start of the rainy season is delayed till june. The southwest winter monsoon flows as a shallow humid layer of surface air less than 2,000 metres about 6,600 feet overlain by the primary northeast trade wind, which blows from the sahara and the sahel as a deep stream of dry, often dusty air. The climate of nigeria, in west africa on the gulf of guinea, is tropical, and it tends to be hot all yearround.

The first, is the hot, dry tropical continental air mass of the northern high pressure system, which gives rise to the dry, dusty, harmattan winds which blow from the sahara over most of west africa from november to february. The most important consequence of this shifting is the annual alteration of wet and dry seasons in tropical africa. At the gulf of guinea, precipitation is abundant yearround without a marked dry season. South floridas subtropical climate is characterized by warm, humid, rainy summers and mild, dry, pleasant winters with periodic incursions of cool air. Villagers pass a submerged rice paddy during a monsoon in nischintapur, bangladesh. Between december and february no rain will fall at all. We previously discovered a similar strengthening of the sahara heat low was linked with later wet seasons over west africa dunning et al. Anomalously wet and dry rainy seasons in equatorial east. Concurrently with the rainfall decline over eastern africa is a decrease in the surface pressure over arabia in may. The implication is that there is a prolonged rainy season in the far south of nigeria, while the far north undergoes long dry periods annually.

West africa has both wet and dry seasons due to being at the intersection of two large air masses. Climate, climate change, the dry and wet seasons in west. What is the reason for alternating wet and dry seasons in savanna type climate. Monsoons cause wet and dry seasons throughout much of the tropics. During the wet season, a lot of rain falls, causing rivers to fill up or even flood. This lack of water and hence of food may force many grazing animals to migrate to more fertile spots. Dry season determinants of malaria disease and net use in. Subsaharan africa suffers by far the greatest malaria burden worldwide and is currently undergoing a profound demographic change, with a growing proportion of its population moving to urban areas.

Jacob bjerknes, a norwegian meteorologist, would later recognize that the circulation of winds, rain, and weather was part of a pacificwide air circulation pattern he called walker circulation. Others have scorching hot summers and windy, wet winters. In july, when the sun is over the tropic of cancer, the itcz reaches its northernmost position at about 15n. Oddly enough, it is actually a little cooler during this dry season.

Winter temperatures are usually between 30 and 65 degrees. At higher latitudes, precipitation decreases and is limited to a wet season of decreasing. Objective seasons in the top end of the northern territory are generally known as the wet and the dry. But even then, its nowhere as low as winter temperatures in europe.

Also, there is no distinct rainy season like in monsoon climate. The rainfall varies and can even miss an area leading to drought. West africa has wet and dry seasons resulting from the interaction of two migrating air masses. In general what happens in the wilderness areas of africa is that with the dry season much of the. Jan 10, 2016 so rainfall decreases from east to west here. Tropical wet and dry climate is mainly found within the tropics. A monsoon is actually a seasonal shift in wind direction and pressure distribution that causes a change in precipitation. As a result of these interacting air masses, west africas precipitation regime is characterized by latitudinal belts of decreasing rainfall and wet season length. West africa generally, the dry season runs from november to april in west african countries like ghana and senegal. In the savanna of west africa, there is a wet season and a dry season. During the dry seasons plant life and animal life suffers, but as the rainy season begins life flourishes in this area. Urbanisation is generally expected to reduce malaria transmission.

Generally, the dry season runs from november to april in west african countries like ghana and senegal. Nigeria, therefore, has two major seasons, the dry season and the wet season, the lengths of which vary from north to south. Savanna climate or tropical wet and dry climate or sudan climate this type of climate has alternate wet and dry seasons similar to monsoon climate but has considerably less annual rainfall. Although humidity is high throughout the year especially on the coast, there are less mosquitoes during the dry season and unpaved roads are also in the best condition.

An alternative subdivision recognizes savanna woodland, with trees and shrubs forming a light canopy. The wet season sometimes called the rainy season is the time of year when most of a regions average annual rainfall occurs. The climate is known for warm to hot, dry summers and mild to cool, wet winters. It is located between 5 and 25 degrees latitude, in central and south america, africa, australia and asia. In the dry season only an average of about 4 inches of rain falls.

Most of africa experiences a wet season and a dry season each year. It is located between 5 and 25 degrees latitude, in central. There is a rainy season in this case, the monsoon season, which lasts two to three months at latitude 16 n on the west coast, three to four months at 14 n, six to seven months at 10. The southern parts have one wet season and one dry season whereas east africa will have the dry season but also have two wet seasons. Wet and dry seasons questacon the national science and. Derived from mauism, the arabic word for season, a monsoon often refers to a rainy season but this only describes the weather a monsoon brings, not what a monsoon is. Between the tropics and the equator, locations may experience a short wet and a long wet season. The west of the country becomes rainy but showers occur after noon with sunny half of a day before. In nigeria as well as in most part of africa there are only two seasons in a year.