GEOGRAPHY FORM FOUR: Topic 2: CLIMATE AND NATURAL REGIONS
Climate is the average weather conditions of an area observed and recoded over a long period of time (about 30 years). This involves systematic observation, recording and processing of the various elements of climate such as rainfall, temperature, humidity, air pressure, winds, clouds and sunshine before any standardization of the climatic means or average can be arrived at. Weather: The conditions of the atmosphere which occur at a place at specific time period from hour to hour or day to day. The weather should not be equated with climate, though they are very closely related to each other in the study of meteorology and climatology. For example when we say climate of Tanzania is hot wet equatorial climate that is the summing up of the average everyday weather conditions of the country throughout the year.
FACTORS INFLUENCING CLIMATE
a) Latitude -Influences temperatures on the surface of the earth whereby the areas nearer to the Equator experience higher temperature than those far away. -Shifting of the overhead position of the sun is determined by latitudes and has an influence on climate.
b) Altitude -Influences temperature and pressure of a region. -Low altitude regions are warmer and experience high atmospheric pressure while high altitude areas are cooler and have low pressure.
c) Distance from the sea -Has an influence in both temperature and rainfall of a region. During summer onshore winds have cooling effect on the land which is warm. -During winter the sea is warmer than the land.
d) Aspect Aspect refers to the direction in which a slope faces e.g in The Northern Hemisphere; the Southern ward slopes are warmer than the North ward facing slopes. This is because the North slopes never receive direct sunshine as the sun in this region never gets overhead. -Windward slopes of highlands receive much higher rainfall than the Leeward slopes.
e) Ocean Currents Current flowing along the Coasts tend to modify the climate of the Coastal regions. Where onshore wind blow over a cold ocean current are cooled from the below and the moisture they are carrying is condensed and dropped over the sea as rain.
f) Prevailing Winds Wind is a medium of transfer of heat and moisture over the land. If wind is blowing from a warm region, it has the warming effects over the region it is blowing across and if wind will blow from cold region it will be cold and will cool the land over which it is blowing.
g) Human Activities Like development of settlements, agriculture and construction of dams and creation of manmade lakes have influence on climate. In recent times we are realizing the effects of human activities in causing climate change, caused by clearing of forests , draining and cultivating swamp areas, emission of Chlorofluorocarbons and other gases from factories and motor vehicles.
CLIMATE AND NATURAL REGIONS OF THE WORLD
Climate is not the uniform across the World; climate varies from one place to another. Mainly Variation of temperature and rainfall influences different climatic characteristics. This gives rise to various climatic regions around the globe. Natural Regions are geographical areas with uniform physical characteristics that distinguish it from other natural regions. The four types of climate are hot, warm, cool, and cold climates. Each of these climates is further subdivided into different subtypes as it will be explained in detail below:
i. HOT CLIMATES
These are the type of climates found within the tropics, mainly between 23½° north and 23½° south of the equator. Hot climates include the following climate sub types:
1. Equatorial climate
2. Tropical continental climate
3. Tropical monsoon climate
4. Tropical marine climate
5. Tropical desert climate
Equatorial climate
Location The region is found between 0° and 5° north and south of the equator but in some regions it may extend up to 10° north or south of the equator. Examples of areas found within this region include the Amazon basin, Congo basin, the southern Ivory Coast, south Ghana, western coastal Nigeria, and eastern coastal Malagasy Republic.
Climatic characteristics
1. There are no marked seasons of the year
2. High temperature about 270C throughout the year
3. The annual temperature range is about 3°C.
4. The daily mean temperatures are about 26°C all the year round.
5. The daily temperature range is rarely more than 8°C because of the thick cloud cover.
6. Rainfall is heavy and is usually convection rain.
7. Rainfalls usually occur in the afternoons and they are accompanied by lightning and thunder.
8. The annual rainfall is about 2000mm
9. High humidity and intensive cloud cover throughout the year.
10. Crops grown are cassava, groundnuts, maize, millet, beans, bananas.
11. Human activities: Plantation agriculture, fishing, cultivation, peasantry sedentary agriculture.
12. Common animals found: Monkey, gorillas, crocodiles, and hippopotamus. NB: But areas located in highlands within the equatorial region have their temperatures modified by altitude. The temperature of some of these highland areas, e.g., the East African Highlands, is lowered to about 15°C. These regions are said to have a modified equatorial climate. Variations on the basic type of climate occur in the highland regions of equatorial Africa. The climate of most of these regions has an equatorial rainfall pattern. Tropical continental climate This climate is also known as Sudan type or Savannah climate. In the interior of the continents it is referred to as tropical continental climate. Location Location: the region is found between 5° - 15° north and south though it may extends to 250 north or south of the equator. Area found: East and Central Africa, Brazilian plateau, Venezuela, Africa and N. Australia. Climate: hot wet summer season, warm dry winter, rainfall is moderate. Torrential rainfall associated with thunderstorms in annual range of temperature increases with the distance from equator.
Climatic characteristics
1. High temperature, in hot summers (320C) and cooler winters (200C).
2. The annual temperature range is about 110 C.
3. The highest temperatures occur just before the rainy season begins.
4. Heavy rains, mainly convection, occur in the summer.
5. Total annual rainfall is around 765mm, though this increases in the areas lying close to the equatorial climate region. Similarly, rainfall decreases towards the tropical deserts.
6. Humidity is high during the hot, wet season. This climate is characterized by tall grass and trees which are more numerous near the equatorial forest region. The savannah region is suitable for herbivores animals such as giraffes, elephants, buffaloes, rhino, zebras, antelopes, wildebeests and many other animals. There are also carnivorous animals such as lions, leopards, hyenas, etc. The region also supports a variety of species of birds, reptiles and insects. People living in this region mainly engage in livestock keeping, cultivation and tourism. Also lumbering is practiced. Many tourists come from foreign countries to view the wildlife that live in the vast grassland. Numerous national parks have been established in this region. In Tanzania, for example, there are established national parks such as Serengeti, Mikumi, Selous, Tarangire, Ruaha, Saadani, Ngorongoro, Katavi and Manyara. The major crops grown in this region are maize, millet, groundnuts, beans, onions, cotton, tobacco, sugarcane, sisal, rice and coffee. Tropical monsoon climate Location The areas which mainly experience monsoon type of climate are South East Asia, Northern Australia, Southern China, and the Indian subcontinent. This type of climate is most marked in India.
Climatic characteristics
1. Seasonal reversal of winds (monsoon winds); onshore during one season and offshore during another season.
2. Onshore wind brings heavy rain to coastal regions while offshore winds bring little or no rain, except where they cross a wide stretch of the sea.
3. Temperatures range from 32oC in the hot season to about 25oC in the cool season, giving an annual range of about 7oC.
4. Annual rainfall varies greatly, depending on relief and the angle at which onshore winds meet the highlands (aspect).
5. There are three marked seasons: cool, dry season; hot, dry season; and hot, wet season. This climate can generally be described as having a hot, wet season and cool, dry season. The main human activities carried out in areas experiencing this type of climate include rice growing and livestock husbandry. Apart from rice, the other crops grown are wheat, millet, maize, and sorghum. Sugarcane, cotton and juice are important lowland crops grown in India, Pakistan and Bangladesh. The other crops grown are tea (Sri-lanka, Bangladesh and India) and rubber in Malaysia. Animals kept in this climatic region include pigs, cattle, buffalos, sheep, goats, and poultry.
Tropical marine climate
Location Regions with this type of climate are located on the east coasts of regions lying between 100 N and 250 N and 100S and 250 S. These areas are under the influence of onshore trade winds. The main areas are the east coasts of Brail and Malagasy, the lowlands of Central American and the west indies the coast of Queen land (Australia) and the southern Islands of the Philippines.
Climatic characteristics
1. Temperature characteristics are similar to those of the equatorial climate.
2. Hot season temperature is 290C and cooler season temperature is 210C.
3. Annual temperature range is about 80C.
4. Total annual rainfall varies from 1000 mm to 200 mm depending on the location.
5. Rainfall is both convection and topographic (brought by onshore trade winds).
6. Maximum rainfall occurs in the hot season.
7. High humidity throughout the year. This climate can generally be described as hot and humid throughout the year. However, the climate is cooled by the onshore winds blowing almost everyday. The main human activities carried out in this climatic region include crop cultivation, lumbering and animal rearing. The crops grown include sugarcane, rice, banana and wheat. The animals kept are such as cattle, pigs, sheep, goats and poultry.
Tropical desert climate Location
The tropical desert climate occurs on the western margins of landmasses between latitude 20o to 30o north and south of the equator. The climate is experienced in all the major tropical deserts of the world. The hot deserts occupy about one third of the earth’s surface. The principal tropical deserts occur on the continents as follows:
1. Africa: Sahara, Kalahari and Namib Deserts
2. Asia: the desert of Jordan, Syria, Iran, Iraq, Saudi Arabia and Israel, and the desert of India.
3. North America: Mohave, Colorado and Mexican Deserts.
4. South America: Atacama Desert
5. Australia: Great Australian Desert
ii. WARM CLIMATES
Warm climates border the hot tropical deserts. They occur between 300 and 400 north and south of the equator. There are four broad types of warm climates:
1. Warm temperature western margin.
2. Warm temperature continental.
3. Warm temperature eastern margin.
4. Warm temperature desert. Warm temperate western margin (Mediterranean type) This is also known as the Mediterranean climate Location This type of climate occurs between 300 N and 450 N and 300 S and 400 S on the western sides of the continents. Places experiencing the Mediterranean climate are on the coastal lands around the Mediterranean Sea (the Maghreb, Spain, Italy, Greece, Egypt and Israel), the western sides of north and South America (central California and central Chile), South Australia (Perth and Adelaide) and South Africa (Cape Province).
General characteristics
1. Temperatures range from 210 C in the summer to 100 C (or below) in the winter.
2. Mean annual temperature is about 150C.
3. Annual total rainfall varies from 500 to 900 mm.
4. Hot, dry summers and cold, wet winters. This is because westerly winds blow off shore in the summer and on shore in the winter. The Mediterranean climate can generally be described as having hot, dry summers and middy, rainy winters. The climate permits a wide range of crops to be grown, which include fruits and cereals. It is in this region that much of the world’s citrus fruits are grown. Citrus fruits include oranges, lemons, grapes and limes. Other fruits grown here are peaches, apricots, plums, cherries, olives, almonds and pears. The cereals include maize, wheat, rice and barley. Agriculture has given rise to specialized industries such as wine-making, flour-milling, fruit canning and food processing industries. Warm temperate continental (steppe type) This type of climate is also known as warm temperate interior region Location It occurs in the interior of the continents, between 20o and 35o north and south of the equator. The best examples of the areas having this climate are Murray-Darling lowlands of Australia; The high Veldt of South Africa; and the central Paraguay and central Argentina (both in South America); central lowlands of north America (Oklahoma and Texas and in northern Mexico); central European lowlands, and the plains of Manchuria.
Climatic characteristics
1. Temperatures range from 26oC in the summer to 10oC in the winter.
2. The annual rainfall varies from 380 to 700 mm, depending on the distance from the sea.
3. Rainfall is convectional type and falls mainly in spring and early summer. The main economic activities carried out in this region are cattle rearing and crop growing. Tourism is also practiced. Warm temperate eastern margin (China type) Location It occurs in the eastern sides of the continents between latitudes 230 and 350 north and south of the equator. The countries having this type of climate are central China, south eastern USA, and southern Brazil, eastern part of Argentina, South Africa, southern Brazil, and eastern part of Argentina, South Africa, southern Japan, and south eastern Australia.
Climatic characteristics
1. Temperatures are about 26oC in summer and 13oC in the winter.
2. The total annual rainfall varies is about 1000 mm.
3. The rain is convectional and torrential type and it mostly falls in the summer. Temperatures and rainfall in this type of climate make it possible to grow crops and keep animals. Lumbering is also practiced in the forested areas. The crops grown include rice, maize, cotton, sugarcane and tobacco. Animals are extensively kept in Argentina and Australia. The animals produce products such as meat, milk, butter and cheese for consumption and export. Warm temperate desert This type of climate is also called mid-latitude desert climate. The areas having this type of climate include Nevada and Utah states of North America and Pentagonia in South America. It is also found in regions that extend from Turkey, northern Iran, across the Caspian sea and Aral areas into former USSR. It is also experienced in the Gobi desert of Mongolia.
iii. COOL CLIMATES
These climates are experienced in regions between 350 north and 600 south of the equator. They are characterized by definite seasonal variations in temperature.
There are four types of cool climates:
1. Cool temperate continental (British type).
2. Cool temperate continental (Siberian type).
3. Cool temperate eastern margin (Laurentian type).
4. Temperate desert. Cool temperate western margin (British type) Location It occurs on the western sides of the continents between 450 and 600 north and south of the equator. Areas with this type of climate include North West Europe, British Columbia in western Canada, Southern Chile, Tasmania, and the south Island of New Zealand.
Climatic characteristics
1. Winter temperatures range between 20 C and 70 C, while summer temperatures range from 130 C to 150 C.
2. The annual temperature range is between 80 C and 110 C.
3. Rain falls throughout the year, with maxima in winter.
4. The total annual rainfall is about 760 mm.
5. The rain is both convectional and cyclonic in nature. People living in this region engage in a myriad of economic activities which include agriculture, mining, lumbering, manufacturing and commerce. Agriculture is of extensive type and includes keeping of beef and dairy cattle and sheep and the growing of wheat, barley oats, vegetables and fruits. In British Columbia lumbering is an important economic activity. In Tasmania and New Zealand, sheep rearing for wool and mutton is an important activity. Fruit farming, especially apples, is practiced throughout the region. Cool temperate continental (Siberian type) Location This type of climate is found extensively in the northern hemisphere. It occurs in the interiors of North America and Eurasia between 35o and 60oN
Climatic characteristics
1. Moderately warm summers (18o) and very cold winters (-19oC).
2. The annual temperature range is very high (37oC).
3. Most of the rain falls in the summer.
4. The rain is convectional type and is often accompanied with thunder.
5. The annual precipitation (rain plus snow) ranges from 400 to 500 mm. The main human activities in this region include lumbering fishing, mining and some agriculture. Cool temperate western margin (Laurentian type) Location This type of climate is found extensively in the northern hemisphere. It occurs in the interiors of North America and Eurasia between 35o and 60oN
Climatic characteristics
1. (a) Moderately warm summers (18o) and very cold winters (-19oC).
2. The annual temperature range is very high (37oC).
3. Most of the rain falls in the summer.
4. The rain is convectional type and is often accompanied with thunder.
5. The annual precipitation (rain plus snow) ranges from 400 to 500 mm. The main human activities in this region include lumbering fishing, mining and some agriculture. Cool temperate western margin (Laurentian type) Location This type of climate is found extensively in the northern hemisphere. It occurs in the interiors of North America and Eurasia between 35o and 60oN
Climatic characteristics
1. (a) Moderately warm summers (18o) and very cold winters (-19oC).
2. The annual temperature range is very high (37oC).
3. Most of the rain falls in the summer.
4. The rain is convectional type and is often accompanied with thunder.
5. The annual precipitation (rain plus snow) ranges from 400 to 500 mm. The main human activities in this region include lumbering fishing, mining and some agriculture Cool temperate western margin (Laurentian type) Location It occurs on the eastern sides of the continents between 35oN and 5oN, and south of 40oS. It is experienced mainly on the eastern sides of North America and Asia
Climatic characteristics
1. Winter temperatures range from -10oC to 4oC.
2. Summer temperatures range from 12oC to 24oC.
3. The annual temperature range is large and averages 24oC.
4. Precipitation (in the form of rain and snow) is distributed throughout the year.
5. Annual precipitation varies between 700 and 1000 mm.
6. Rainfall is both convectional and cyclonic. The main economic activities in this region are farming, mining, and manufacturing. The crops grown include wheat, maize, millet and soya beans. Sheep farming is important in Patagonia. Mining and manufacturing are practiced where minerals are found. Temperate desert Location This climate occurs in the interiors of Eurasia and North America, and in Patagonia (South America).
Climatic characteristics
1. Winters are very cold with temperatures often below -7oC.
2. Summer temperatures vary between 25oC and 37oC.
3. Diurnal temperature range is about 35oC while the annual temperature range is about 40oC.
4. Precipitation is very low, it averages about 250 mm.
5. Most of the rain falls in late winter and early spring. The human activities carried out in this region include mining, animal rearing and some agriculture. The animals reared are such as camels, donkeys, sheep and goats. The main crops grown in this region are date palms, oil palms, and millet. Agriculture is mostly practised in oases and along river valleys. iv.
COLD CLIMATES
Cold climates are mainly experienced in regions between latitudes 600 N and 680 N There are three types of cold climates:
1. Cold temperate western margin.
2. Cold temperate eastern margin.
3. Cold temperate continental. Cold temperate western margin Location This climate is confined to coastal areas of Scandinavia and Alaska.
Climatic characteristics
1. Short, cold summers with temperatures of about 12oC.
2. Long winters with temperatures ranging from -2oC to 4oC.
3. Annual rainfall is about 750 mm.
4. Rain falls in most months except the winter when show falls. The main economic activities practiced in this region include agriculture, mining and manufacturing. A dairy cattle farming is mainly practiced in the Scandinavian countries such as Norway Denmark and Sweden. Cold temperate Continental Location This climate occurs between 55oN and 68oN in the interior of America and Eurasia.
Climatic characteristics
1. Cold and long winters with temperatures ranging between -340 C and -450 C.1
2. Warm and short summers with average temperatures up to 210 C.1
3. Annual precipitation is very low, about 380 mm.1
4. Most of the rainfalls in summer, but in winter, precipitation is in the form of snow.
Cold temperate eastern margin
This climate occurs in the north east pacific of Russia. Climatic characteristics
1. Long, cold winters with an average temperature as low as -200 C or below.131
2. Short, hot summers with an average temperature up to 210 C or higher.1
3. Total annual rainfall varies between 500 and 1000 mm.
ARCTIC CLIMATES
These types of climates are experienced in regions beyond the Arctic Circle (661/20 N) and around Arctic Ocean. They are also known as polar deserts. The main features of these climates are low amounts of precipitation (rain), mild summers and very cold winters. Arctic climates comprises of Tundra and Polar climates Tundra climate Location This region occurs in the northern coast of North America, southern coast Greenland and the Arctic coast of Europe and Asia.
Climatic characteristics:
1. Very long, cold winters with temperatures ranging between -290 C and – 400 C.
2. Short, cool summers with temperatures of about 100 C.
3. Annual precipitation is 250 mm; some of it falls as snow in winter and as rain in summer. Polar climate Location It occurs in the interiors of Iceland, Greenland and Antarctica.
Climatic characteristics
1. Temperatures are permanently below 00 C.
2. Precipitation is in the form of blizzards (now storms).
3. The winters consist of continuous night, and summers of continuous day. Because temperatures are very low, most these regions are uninhabited and hence limited human activities take place here. The natural occupations are hunting, fishing and herding of reindeer. Mountain climate This type of climate occurs in the main mountain areas of the world. The areas that experience such climates include the East Africa Mountains, the Ethiopian highlands, the mountains and plateaus of central Asia, the Alps of Europe, the Andes of South America and the Rockes of North America.
Climatic characteristics
1. Pressure and temperature generally decrease with increase in altitude.
2. Precipitation increases with altitude.
3. In areas around mountains within the tropic, temperatures may range from high at the foot of a mountain to very cold at the peak, e.g. Mount Kilimanjaro. We have seen how particular climatic conditions influence human activities. Now, let us see how specific climatic conditions are suitable for given human activities.
CHARACTERISTICS OF THESE REGIONS
- They experience similar problems.
- They have same geographical back ground.
- Are unified by the same certain latitudes which help in locating them over.
- Tend to have almost the same type of soil and vegetation cover.
- They have the same occupation such as a mining, agriculture and animal husbandry.
WORLD MAP SHOWING DIFFERENT NATURAL REGIONS
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