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Geography

WEATHER FORECASTING

Prediction of the conditions of the atmosphere for a given place for a certain period. Methods of Weather Forecasting Traditional Methods – Prediction of weather based on traditional beliefs and facts. Plants shedding leaves indicates period of drought. Safari ants indicate it will rain. Migration of butterflies also indicates it will rain. Croaking of frogs during dry season indicate its going to rain. Flowering of certain plants indicates the onset of rainfall. Changes in the intensity of sunshine indicate its going to rain.   Modern Methods -Prediction of weather using modern instruments and new technology of collecting, transmitting, processing and analysing weather data. Instruments Used Satellites-electronic devices which orbit the earth which collect and transmit weather data which is interpreted by computers. Radar-an instrument used to see cloud formation. Sensors/radiosodes-instrument fixed on a balloon used to measure atmospheric pressure, temperature and humidity. Computers-electronic device used to store, analyse and display… Read More »WEATHER FORECASTING

Geography

ATMOSPHERIC PRESSURE

The force exerted by gases in the atmosphere on some area or body on the earths surface. Measured using barometers of three types namely mercury, aneroid and Fortin Barometers How It Works Air exerts pressure on the mercury in the beaker. The height of mercury in the tube is proportional to the atmospheric pressure. The readings are taken in mmHg. Its 760mmHg at sea level   Advantage Quite accurate Disadvantage Cumbersome to carry around. Can be damaged quite easily while being carried around.   Aneroid Barometer -Measures changes in atmospheric pressure. How It Works Has air tight compartment (vacuum). Compartment expands when pressure decreases. It collapses when pressure increases. The movement is transmitted by lever to a pointer on a dial. The readings are in kg/cm3.   Evaporation The rate and amount of evaporation is measured using piche and tank evaporimeters. Piche Evaporimeter When there is a lot of sunshine… Read More »ATMOSPHERIC PRESSURE

Geography

WIND

Direction Wind direction is determined using wind vane. How It Works As the wind blows the arrow swings. The arrow points in the opposite direction of the wind flow. The direction is read from the cardinal compass points. The arrow will point in the direction from which the wind is blowing. For instance if it points S the wind is blowing from S towards N. Wind Sock – Used to indicate the general direction of wind flow. – Not kept in a weather station because it doesn’t give the accurate direction of wind flow. – Seen near airstrips for the benefit of pilots. How it Works When wind blows the bas stretches out in the direction that the wind is blowing. Wind speed/Velocity – Measured using anemometer. How It Works When wind bows hemispherical cups rotate. The number of rotations is obtained from the metre on the lower part of… Read More »WIND

Geography

HUMIDITY

Humidity is the condition of atmosphere with reference to its water content. It’s measured with hygrometer or psychrometer which consists of wet and dry bulb thermometers kept in Stevenson screen. Dry bulb thermometer is a thermometer covered with muslin bag immersed in water while dry bulb thermometer has no muslin. How It Works When air is dry there is a lot of evaporation from the muslin. Evaporation cools the bulb of thermometer resulting in a low temperature reading. When humidity is high there is little evaporation from the muslin. The wet bulb thermometer is cooled at a slower rate and both thermometers show almost the same temperature reading. The difference in readings between the two thermometers is used to determine relative humidity.                                Interpretation of Hygrometer Readings When the 2 readings are the same, relative humidity is 100% i.e. the air is saturated. If the difference is small, humidity is… Read More »HUMIDITY

Geography

SUNSHINE

Duration of sunshine is measured using Campbell stokes sunshine recorder. How It Works Spherical lens focuses light on sensitized paper. The paper burns when the sun is shining. The total hours of sunshine is got by adding all the burnt sections from calibrations on the side of sensitized paper. The sensitized paper is changed every day.

Geography

RAINFALL

Rain gauge is the instrument used to measure the amount of rainfall in a day. It should be made of impermeable material which can’t absorb water. How It’s Used/Works It’s taken to an open space to prevent water from dropping into the funnel. Its sunk into the ground to prevent evaporation The funnel top is left 30cm above the ground to prevent splashes of water and run off. After 24 hours water is emptied into the measuring cylinder. The reading of the amount of rainfall is got from the measuring cylinder in millimetres. The figure represents the millimetres of water falling on each square millimetre of the ground. It could be used to measure snow fall by melting it before the readings are gotten.   Calculating Rainfall Monthly Rainfall Total -Sum of rainfall recorded in a month. Annual Rainfall Total – Sum of monthly rainfall totals for 12 months. Mean… Read More »RAINFALL

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TEMPERATURE

Degree of hotness of an object or a place. It’s measured using 3 types of thermometers namely: Maximum thermometer Minimum thermometer Six’s thermometer   Maximum Thermometer It’s used to measure the highest temperature reached in a day. It uses mercury. How It’s Used/Works Temperature rises causing mercury to expand. Mercury pushes the index up. When temperature falls mercury contracts. The maximum temperature is read from the scale at the lower end of the index. Thermometer is reset by shaking it to force mercury back into the bulb.   Minimum Thermometer It’s used to record the lowest temperature reached in a day. It uses alcohol. How it’s Used/Works Temperature falls causing alcohol to contract. Alcohol pulls the index down. When temperature rises alcohol expands and rises in the tube. The index remains where it was pulled. Minimum temperature reading is obtained from the scale at the lower end of the index.… Read More »TEMPERATURE

Geography

THE STEVENSON SCREEN

A white wooden box mounted on 4 legs used to house thermometers and hygrometers. The instruments which are found in it are: Maximum thermometer Minimum thermometer Six’s thermometer hygrometer-wet bulb and dry bulb thermometer Importance Provide shade conditions for accurate temperature recording. Ensure safety of thermometers because they are delicate.   Qualifications Which Make Stevenson Screen Suitable For Its Work Painted white for little absorption of solar heat energy. Made of wood which is a bad conductor of heat. Well ventilated to allow easier flow of air inside it. Raised to prevent contact with terrestrial radiation. Has double roof which acts as an insulator to prevent direct heating from the sun. Recording and Calculating Weather Conditions See also BUSH FALLOWING IN WEST AFRICA MINING MINERALS IN EAST AFRICA PROBLEMS ENCOUNTERED IN FIELD WORK  

Geography

THE WEATHER

Daily atmospheric conditions of a place at a particular time. Elements of Weather Temperature Humidity precipitation Precipitation Atmospheric pressure Wind Sunshine Cloud cover   A Weather Station -A place where observation, measuring and recording of weather elements is done Factors to Be Taken Into Account When Sitting a Weather Station An open place where there is little obstruction of weather elements. Accessible place so that recording can be done easily. A fairly level or gently sloping ground (5◦) so that it’s easy to position weather instruments. The place should provide a wide view of the surrounding landscape and the sky. The site should be free from flooding. The place should have security.   Instruments for Measuring Elements of Weather Thermometer-temperature Hygrometer-humidity Rain gauge-rainfall Barometer-air pressure Sunshine recorder-sunshine duration and intensity Wind vane –wind direction Anemometer-wind speed Evaporimeter-rate and amount of evaporation.   See also BUSH FALLOWING IN WEST AFRICA MINING… Read More »THE WEATHER

Geography

EXTERNAL STRUCTURE OF THE EARTH

a) The Atmosphere Layer of gases surrounding the earth. The earth revolves with it because it’s held onto it by gravity It’s about 330km thick.   Composition of the Atmosphere a) Gases-exist as a mixture b) Smoke particles c) Dust particles d) Water vapour   The structure of the Atmosphere It’s divided into 4 layers/zones namely: Troposphere Lowest layer of the atmosphere Contains 90% of water vapour Rainfall is got from it Temperature decreases with increase in altitude (lapse rate) Air is turbulent due to mixing of air Contains dust particles There is a zone of transition between troposphere and stratosphere called tropopause. Stratosphere/ozonosphere Layer lying next to troposphere Has layers Lower isothermal layer in which temperature is constant Upper layer of temperature inversion in which temperature increases with increasing altitude Has ozone layer which absorbs harmful ultraviolet radiation. Air is calm so it’s used by passenger jets Limited amounts… Read More »EXTERNAL STRUCTURE OF THE EARTH

Geography

THE STRUCTURE OF THE EARTH (Internal Structure)

Internal Structure of the Earth The evidence used to study the earth’s interior are mining drilling quarrying/excavation Crust/Lithosphere Outermost layer of the earth Made of soils and other loose deposits of sand The dominant rocks are granites. Extends 0-50km Has 2 layers Sial Also called continental crust Made of light coloured rocks Called sial because it’s made up of silica and aluminium. Sima Also called oceanic crust Mainly made of basaltic rocks which are brittle. Called sima because it is made of silica magnesium and iron.   Mohorovicic Discontinuity (Moho) A definite zone of discontinuity between the crust and the mantle. Was discovered by Dr. Andrija Mohorovicic in 1909. The Mantle/Asthenosphere Layer lying between the crust and the core Made of iron and magnesium Has two layers Upper mantle Rocks are more elastic than those of sima. Temperature is about 1000◦c. lower mantle Rocks are like very viscous liquid. Temperature… Read More »THE STRUCTURE OF THE EARTH (Internal Structure)

Geography

REVOLUTION OF THE EARTH

Movement of the earth in its orbit around the sun. It’s in anticlockwise direction. The orbit of the earth’s revolution is elliptical. Takes 365 ¼ days in a year or 366 days in a leap year (every 4 years). The sun moves from the tropic of cancer to the equator and then towards tropic of Capricorn and back to the tropic of cancer. 21st march and 23rd September are called equinoxes because the length of day and night is equal.   The sun is vertically overhead at noon at the equator. 21st June is called summer solstice because its summer in the N hemisphere. The sun is vertically overhead at noon at the tropic of cancer. 22nd December is called winter solstice because its winter in the S. hemisphere. The sun is vertically overhead at noon at noon at the tropic of Capricorn. Solstice is the period of maximum tilting… Read More »REVOLUTION OF THE EARTH

Geography

THE ORIGIN OF THE EARTH

A star with a greater gravitational pull passed near the sun. It attracted large quantities of gaseous materials from the sun. The materials split, cooled and condensed. Heavier materials collected at the centre to form the core. Less dense materials collected around the core to form the mantle. The lightest materials formed the crust   The shape of the earth The shape of the earth is called geoid/ovoid/oblate spheroid due to being an imperfect sphere by being wide at the equator and flat at the poles.   Proofs/Evidence That the Earth Is Spherical If one moves towards the east in a straight line he will end up where he started. Satellite photographs taken from space show that the earth is like a sphere. Places in the east see the sun earlier than those in the west. When a ship is approaching the smoke is seen first, then the mast and… Read More »THE ORIGIN OF THE EARTH

Geography

CALCULATION OF LOCAL TIME

The time recorded in places within the same longitude. A longitude is an imaginary line running from N to S which shows how far E or W a place is from the prime meridian. Greenwich Meridian (0◦) longitude is the point of reference when calculating time. Time is gained towards the E and lost towards the W. Examples Suppose the time at GWM is 12 noon what is the local time at Jos 40◦E? Time gained=40×4=160min=2 hours 40min Local time at Jos is 12.00+2.40=14.40-1200=2.40pm. At Dar-es-Salaam 40◦E time is 12pm what is the time at Ecuador 40◦E? 40◦+20◦=60◦ 60×4=240min=4hours Ecuador is behind in time =12.00-4=8 am. If the places are on the same side subtract the degrees to get the difference and add or subtract from the reference time depending on which side the place is.   Calculation of Longitude What is the longitude of place x whose local time… Read More »CALCULATION OF LOCAL TIME

Geography

NATURAL SATELLITES

Any natural heavenly body that orbits around a planet e.g. moon for earth, tritan for Saturn and triton for Neptune. Asteroids/Planetoids Also called minor planets. Are small fragments of rocks left going around the sun when the solar system was formed Found between Mass and Jupiter Are 1500 in number They sometimes collide with each other and planets due to Jupiter’s gravitational pull causing them to move in erratic orbits. Comets Heavenly bodies which appear to have a head and a long tail Made of ice, dust and frozen gas The head is made of many particles of dust, rock and frozen gases. Their tail is made of gases and points away from the sun. Move around the sun in extremely long and oval orbits Their orbits cross the earth’s orbits e.g. Halley’s Comet which appears after every 76 years.   Meteoroid Small heavenly body which strays from its orbit… Read More »NATURAL SATELLITES

Geography

COMPOSITION OF THE SOLAR SYSTEM

The Sun It’s the centre of the universe. Characteristics of Sun It’s a star. A star is a heavenly possessing its own light which it transmits. Nebula/galaxy is a cluster of stars. The earth is in a galaxy called The Milky Way. It’s made of very hot gases mainly hydrogen (70%) and helium (30%). Has a diameter of 1392000km. Surrounded by a layer of gas which has boiled from its surface which is called corona. Rotates on its own axis in anticlockwise direction. Has gravitational pull which holds all the planets in orbit around it. An orbit is a path which a planet or a satellite follows around a star or a planet. Temperature at its centre is 15m◦c and at the surface is 5500◦c. Radiates solar energy which is very important for all forms of life on the earth.   The Planets Planets are large spherical celestial/heavenly bodies in space.There… Read More »COMPOSITION OF THE SOLAR SYSTEM

Geography

THE EARTH AND THE SOLAR SYSTEM

THE EARTH AND THE SOLAR SYSTEM 

Solar system is the group of heavenly bodies comprising the sun and the nine planets.

The origin of the Solar System

Theories

A theory is a set of reasoned ideas intended to explain facts or events

Passing Star Theory
A star with a greater gravitational pull passed near the sun
It attracted large quantities of gaseous materials from the sun
The materials split, cooled and condensed to form planets
The planets were set in orbit by the passing star

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IMPORTANCE OF STUDYING GEOGRAPHY

IMPORTANCE OF STUDYING GEOGRAPHY   Facilitates good relationship among nations by studying geography of other regions of the world. it’s a career subject in that it enables one to go for advanced studies in specialized fields e.g. geography teachers, meteorology, surveying etc. Enables us to appreciate other people’s way of life by learning economic activities of different communities within our country and other parts of the world. Enables us to conserve our environment when we learn negative and positive effects of human activities on the environment. Enables us to conserve our resources when we learn wise use of resources in conservation and management of resources e.g. wildlife, forests, energy, etc. Inculcates in us virtues of cooperation and patience as we work in groups. Makes us to appreciate manual work as we are involved in practical geography which may lead to self-employment. Promotion of industry such as tourism by guiding tourists to… Read More »IMPORTANCE OF STUDYING GEOGRAPHY

Geography

INTRODUCTION TO GEOGRAPHY

 The Meaning of Geography  Scientific study of the earth as a home of man. Study of interrelationship on natural and human phenomena on the earth’s surface. Environment  The surroundings All external conditions surrounding an organism which has influence over its behaviour.   Environment can be divided into two: The Physical Environment Natural physical conditions of weather, climate, vegetation, animals, soil, land forms and drainage. The Human Environment Human activities such as farming, forestry, mining, tourism, settlement, transportation, trade and industry.   Branches of Geography Physical Geography Deals with the study of natural physical environment of human kind. The areas covered include: a) Geology-study of the origin, structure and composition of the earth. It includes study of rocks. b) Geomorphology– the study of internal and external land forming processes and land forms. c) Climatology– the study of climate and weather d) Pedology– the study of soils e) Biogeography– the study of… Read More »INTRODUCTION TO GEOGRAPHY

Geography

MINING IN AFRICA (GOLD, PETROLEUM AND COPPER)

MINING IN AFRICA (GOLD, PETROLEUM AND COPPER)  Mining is defined as the extraction and processing of mineral resources into finished products.  Mining of Gold South Africa is the largest producer of gold in Africa, followed by Ghana, Zimbabwe and Zaire.  Major mining areas include: Witwatersrand near Johannesburg (South Africa) Werksdorp and Welcom in South Africa 3. Dunkua and Tarkwa in Ghana 4. Gatoama and Gwanda in Zimbabwe.   Methods of Mining Gold Gold is mined by the underground or shaft method. Here, vertical shafts are driven through a hole to reach the ore bearing rocks. Explosives are then used to fill the holes to shatter the rocks by blasting. The broken rocks are taken to the surface then to the concentrator that filters out the Gold which is later sent to the smelters for further refining and processing.   Transportation and Marketing In South Africa, Gold is mainly transported by… Read More »MINING IN AFRICA (GOLD, PETROLEUM AND COPPER)

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