Effects of climatic elements

CLIMATE IN NIGERIA

Seasons in Nigeria: There are two types of seasons in Nigeria. These are:

1. Rainy/wet Season: The wet season starts in mid – March and last till July. It is the season of heavy rains and high humidity. Plants loot fresh and green, weeds grow rapidly, flowers are in bloom and garden look attractive. This is the planting season. This is referred to as the long wet period of rain. (The short wet season is a period referred to as the August break, to which reference has already being made.it starts in July to August and last for about month).
2. The Short Wet Season: this follows the August break and last from September to October. The rainfall is not usually as heavy as during the first wet season and the total amount is also less.

In the Southern part of Nigeria, before the short wet season, we have the short dry season in August.

MAP OF NIGERIA SHOWING CLIMATE

Characteristics of Wet Season

• High temperature
• Low pressure
• Prevailing winds
• Heavy rainfall

HIGH TEMPERATURE: Temperature is higher in the North 33⁰ and in the South, 27⁰ due to the effect of the sun being at the tropic of cancer in June. Thus, making the North to be hotter while the moderating effect of the ocean reduces the temperature in the South in June.

LOW PRESSURE: There is low pressure in the North due to temperature in the Sahara in June and the high pressure in the South in June

PREVAILING WINDS: The wind that patronizes the Southern part of Nigeria is the tropical maritime air mass or the South western trade wind which blows from the high pressure belt area in the South in June to the low pressure belt in the North. This them pushes the tropical continental airmass towards the North where the inter-tropical fronts is formed.

HEAVY RAINFALL: Rainfall is heavy in the Southern part of the country. This makes this area to experience double maximum of rainfall while the Northern part experiences only single maximum.

DRY SEASON

The Long Dry Season: The long fry season is usually the time when there is lack of rainfall and the dry atmosphere cause cracks to develop on dry soils. Untarred roads are full of ground dust. The dust, rises behind every moving vehicle in a cloud of millions of suspended particles, to be deposited in thick layers of the vegetation at the side of the roads. Dust settles on everything – furniture, cloth and house tops.

Characteristics of Dry Season

• Low temperature
• High pressure
• Prevailing winds
• Absence rainfall
• Harmattan

LOW TEMPERATURE: The temperature within this period is usually low because the sun is now overhead the Southern hemisphere. Hence, the temperature is lower in the North while it is higher in the South.

PREVAILING WINDS: The prevailing wind that influences the country during dry season is referred to as tropical continental airmass or the North eastern trade wind. This wind then pushes the South west wind further towards the coast where the tropical front is now formed.

ABSENCE OF RAINFALL: The tropical continental airmass, which blows from Sahara desert, to the Northern part of the country makes or renders the North rainless.

HARMATTAN: The dry season brings harmattan which experienced between December and January. The harmattan is cod, dry, dusty and hazy.

HIGH PRESSURE: The pressure system is also reversed. There is high pressure in the North and low pressure in the South in January.

AIRMASSES

1. Tropical Maritime Airmass: This originates from the Sourthern high pressure belts, crosses the equator, picks up moisture from over the Atlantic Ocean and enters Nigeria from the South. It is therefore, warm and wet. It influences the whole of the country in July, but in January, its area is restricted to the Southern coastal lands.
2. Tropical Continental Airmass: The birth place of this airmass is in the Eurasia – Arabia high pressure belts. It picks up little or no moisture on route and it is therefore dry. It travels in the country from the North in the month of October, gain ground bit by bit on the tropical maritime airmass and by January has pushed the latter to the south east thus, extending its influence over 90% of the country starts to retreats at in March and by July, it is completely out of the country.

The two airmasses meet along a slanting surface where they continually rub against each other. This surface is called the Hinter tropical front. The area about this front, where the airmasses to some extent mix as a result of the rubbing is called the Inter-tropical Zone of convergence. This zone moves North and South with the front depending on which airmass gains ground on the other.

3. Equitorial Easterlies: This third airmass is rather erractic cool one which comes from the east and blows in the upper atmosphere along the inter – tropical zone of convergence.

Occasionally, however it diverse down, under cut the tropical matitime airmass on tropical continental airmass and gives rise to a line squall or a dust devil.

CLIMATE OF NIGERIA

Climate can be simply defined as the average weather condition of a place over a long period of time usually between 35 – 40 years.

The country is divided into four climatic regions as itemized below:

• Sub – equatorial climate
• Tropical hinterland climate
• Tropical continental climate
• The high plateaux

SUB – EUATORIAL CLIMATE IN THE SOUTH:

Sub – equatorial climate in the South extends from the coast to roughly 130 – 160km in land. It has over 150cm of rainfall per annum, double maximum rainfall are no month has less than 2.5cm of rainfall. The total annual rainfall increases from 150cm in the West to more than 300cm in the Delta area. Relative humidity is normally over 90% in the early morning, but falls in between 60% and 80% in the afternoon. This area has high temperature of about 27⁰c and it has no annual range temperature i.e.  2 – 3⁰c. The double maxima of rainfall is in June/July and September/October with conventional types of rainfall. It is found in the South in the South, in places such as Warri, Calabar, Port-Harcourt.

TROPICAL HINTERLAND CLIMATE

It compromise of a strip of country approximately 240km wide in the middle of Nigeria. It is bounded in the North by the double maxima rainfall line. The total rainfall is between 100 and 150cm and the region has up to fair months of dry season. Relatives humidity is a 80% in the morning and falls to between 50% and 70% in the afternoon. It has a temperature of over27⁰c and then found in the forest area like Ibadan, Ilorin, Akure, Osogbo etc.

THE TROPICALCONTINENTAL CLIMATE

This is also called the Sudan climate and it is found in Borne, Sokoto, Bauchi, Kano etc. It has a high range of temperature of 11⁰c.

The tropical continental north consists of the remainder the Northern Nigeria where the annual rainfall is between 50 – 100cm.the 50cm is yet lies just outside the country. The region has between four and eight months. The relative humidity is always low between 20% and 40% in January rising to between 60% and 80% in July.

THE HIGH PLATEAU

It has a high moderate temperature between 21⁰c and the temperature range is between 8⁰c and 12⁰c.

The high plateaux of Jos, Adamawa, Obudu and Mambilla belongs to a class by themselves. The temperatures are lower and more equable than in the areas around their rainfall records multiple peaks and the total is higher than in other places on the same latitudes. The mean monthly temperature for Jos is (9⁰52¹N) ranges from 20⁰c in August 25⁰c in April and the rainfall is 140cm per annum while Yola (9^c3¹N) has an annual total of only 100cm.