• Climate measures the average pattern of variation in different meteorological elements over long periods of time.
• The elements include temperature, humidity, atmospheric pressure, wind, precipitation, atmospheric particle count, and other variables.
• Independent study of each element does not give a comprehensive view of climate.
• There could be thousands of different types of climates in the world based on these elements.

Weather & Climate

Weather

• Weather is the state of the atmosphere at a specific location during a short period of time
• It includes various atmospheric phenomena such as temperature, humidity, precipitation, air pressure, wind, and cloud cover
• Climate includes the synthesis of weather conditions prevailing over a specific area for a long time period, generally 30 years
• Weather mainly occurs in the troposphere, which extends from the Earth’s surface to 6-8 km at the poles and about 17 km at the Equator
• Almost all clouds and precipitation occur in the troposphere, where weather is confined
• Phenomena occurring in higher regions of the troposphere and above, such as jet streams and upper-air waves, significantly affect sea-level atmospheric-pressure patterns and thereby affect weather conditions
• Geographic features, such as mountains and large bodies of water, also affect weather
• Ocean-surface temperature anomalies are a potential cause of atmospheric temperature anomalies in successive seasons and at distant locations, leading to the El Niño/Southern Oscillation (ENSO) phenomenon

Climate

• Climate refers to the atmospheric conditions at a particular location over a long period of time.
• It is the long-term summation of the atmospheric elements that constitute weather over short time periods.
• Climate is influenced by solar radiation, temperature, humidity, precipitation (type, frequency, and amount), atmospheric pressure, and wind (speed and direction).

Climatic Regions of World

Hot, Wet Equatorial Climate

• Distribution:
  • 50 North – 100 South from equator
  • Monsoon type climate if away from this region
  • Examples of countries: Ecuador, Colombia, Brazil, Peru, Nigeria, Liberia, Myanmar, Thailand, Cambodia, Malaysia, Java
• Climate:
  • Uniform temperature around 24 to 27ºC throughout the year
  • No winter, small diurnal and annual temperature range
  • Heavy precipitation between 6o and 10 inches, well distributed throughout the year
  • Double rainfall peaks at equinoxes
  • No distinct dry season
• Natural Vegetation:
  • Supports luxuriant tropical rainforest vegetation
  • Amazon tropical rainforest is known as Selvas
  • Evergreen trees yielding tropical hardwood, dyewoods, and cabinet wood
  • Lianas, epiphytic and parasitic plants are also found
  • Trees of single species are very scarce in such vegetation
• Economy:
  • Equatorial regions are generally sparsely populated
  • Primitive people live as hunters and collectors in the forests
  • Shifting cultivation is practiced by more advanced people
  • Plantation crops like natural rubber and cocoa are also grown.
• 

Savanna or Sudan Climate (or Tropical Wet and Dry Climate)

• Savanna or Sudan climate is a transitional climate between equatorial forests and hot deserts.
• It is found within the tropics (Tropic of Cancer & Tropic of Capricorn) and is best developed in Sudan.
• It covers much of Africa, Australia, South America, and India.
• The climate has a distinct dry season in winter and a wet season in summer.
• All the rainfall is concentrated during the summer, causing many plants to die and streams to dry up.
• The long dry season causes animal migration.
• Distribution:
  • Savanna or Sudan climate is found between the equatorial forests and trade wind hot deserts
  • It is located within the tropical latitudes on either side of the equator
  • It is best developed in Sudan where there are distinct wet and dry seasons
  • In the northern hemisphere, this climate is found in Africa and South America
  • In the southern hemisphere, it is found in South America and Australia
• Temperature:
  • Monthly temperatures range from 20 to 32 degrees centigrade for lowlands, but the range increases as one moves away from the equator
  • Annual average temperature is around 18 degrees centigrade
  • The highest temperature occurs just before the onset of the rainy season
  • During the rainy season, overcast skies lead to a drop in temperatures
  • During the hot season, noon temperatures often cross 37 degrees centigrade
  • Clear skies lead to rapid radiation loss at night, and even in the hot season, temperatures drop to below 10 degrees centigrade
  • A typical characteristic feature of Savanna climate is the extreme diurnal range of temperature.
• Precipitation:
  • The climate has a hot, rainy season and a cool, dry season.
  • In the northern hemisphere, the hot and wet season starts in May and ends in September, while the rest of the year is dry and cool.
  • In the southern hemisphere, the rainy season begins in October and ends in March.
  • The length of the rainy season and the total annual rainfall decrease as one moves away from the equator towards the desert fringes.
  • Kano, located in Nigeria, experiences over 80cm of rainfall mostly in the summer.
• Winds:
  • Trade-winds bring rainfall in the coastal areas and are the prevailing winds of the region.
  • They are easterly winds that flow from east to west, resulting in maximum rainfall on the east coasts.
  • The trade-winds are strongest in summer when the ITCZ is positioned over the hot desert.
  • The winds exhaust all the moisture while travelling over the coastal areas, and by the time they reach the continental interiors, they are relatively dry.
  • In West Africa, the easterly trade winds bring dust-laden, dry winds from the Sahara and reach the coast of Guinea. The local name for this hot, dry, dusty wind is Harmattan.
  • Harmattan has a disastrous effect on crops, but it also results in a cooling effect and provides some relief from the damp air of Guinea.
  • Trade-winds are the reason for distinct, alternate dry and wet seasons in the region.
  • In summer, onshore trade winds bring moisture-laden winds causing rainfall, while in winter, the winds are off-shore and keep the weather dry.
• Vegetation:
  • Savanna vegetation consists of tall grass with short trees.
  • Tree density and height decrease away from the equator.
  • Deciduous trees are typical, shedding their leaves during dry season to prevent transpiration losses. Acacia is an example.
  • Hardwood trees, sometimes thorny, exude gum like ‘gum arabic’.
  • Broad-trunked trees act as water-storage spaces that help them survive drought. Baobabs and bottle trees are examples.
  • Grass is very tall and coarse, reaching heights of up to 6-12 feet. Elephant grass is the tallest variety, reaching heights of up to 15 feet.
  • Grass roots are long, reaching down in search of water.
  • Grass appears dormant during the dry season and springs up during the rainy season.
  • Grasslands merge into thorny scrubs towards the desert.
• Wildlife:
  • Savanna is home to some of the largest terrestrial animals on the planet.
  • The two main animal groups are herbivores and carnivores.
  • Famous herbivores include zebra, giraffe, elephant, and antelope.
  • Herbivores have either great speed or camouflage skills to escape carnivores.
  • Important carnivores include lion, hyena, leopard, panther, puma, and jaguar.
  • Reptiles like crocodiles, monitors, giant lizards, rhinos, and hippos are found along rivers and marshy lands.
• Economy:
  • Nomadic pastoralists, such as the Masai, depend on their animal stock for survival
  • Settled agriculture is practiced by tribes, such as the Hausa, who use domesticated animals for crop cultivation
  • Plantation agriculture is developed in northern Australia, eastern Brazil, and central Africa
  • Crops such as cotton, sugarcane, oil palm, groundnuts, coffee, and tropical fruits are cultivated
  • Some tribes cultivate millets, bananas, and vegetables for self-consumption
  • Frequent droughts pose a risk to crop cultivation, particularly in the long dry season
  • Intense rainfall during the rainy season can lead to leaching of topsoil and nutrients, turning soils lateritic and unsuitable for crop cultivation
  • Poor grass quality in the savanna region does not support large-scale animal ranching like in temperate grasslands
  • Meat and dairy production are generally poor, but some regions have leveraged modern science and technology to become leading exporters, such as Queensland in Australia.
• 

Tropical Monsoon Climate

• Monsoon climate is found in the region between the Tropic of Cancer and the Tropic of Capricorn.
• The climate is influenced by the movement of the inter-tropical convergence zone (ITCZ) and is hot and humid throughout the year.
• Monsoons are seasonal winds that blow over landmasses from seas and vice-versa.
• Seasonal reversal in wind direction leads to variations in temperature and precipitation.
• The monsoon climate has three prominent and distinct seasons: summer, winter, and rainy seasons.
• Distribution:
  • They are confined within 5 – 30 degrees latitudes on either side of the equator.
  • Indian subcontinent, Indo-China (Laos. Vietnam, Cambodia), Thailand. southern China and northern Australia are the regions experiencing this climate.
• Winds:
  • Seasonal reversal of winds in monsoon climate due to differential heating and cooling of landmasses and seas
  • During summers, low-pressure region develops over Central Asia due to sun’s position over Tropic of Cancer
  • Asian landmass heats up faster than surrounding seas, leading to higher pressure in northern hemisphere
  • Winter conditions in southern hemisphere cause high-pressure zone over northern Australia
  • Winds blow from Australian landmass towards Java and then towards low-pressure region over Indian subcontinent during summers, called South-West monsoon winds
  • During winters, reversal in wind direction occurs.
• Temperature:
  • The region experiences warm to hot summers due to its proximity to the tropics.
  • The average monthly temperature is above 18 degrees centigrade.
  • In summers, the maximum temperature can reach as high as 45 degrees centigrade.
  • The average temperature in summers is around 30 degrees centigrade, with an overall temperature range of 30 to 45 degrees centigrade.
  • Winters are mild with a temperature range of 15 to 30 degrees centigrade.
  • The mean temperature during winters is around 25 degrees centigrade.
• Precipitation:
  • Region experiences very high rainfall
  • Rainfall is concentrated in a few months
  • Annual average rainfall is around 200-250 cm
  • Some regions have a very high average of around 350 cm
  • Maysynram and Cherrapunji of Khasi Hills (Meghalaya) experience an annual rainfall of over 1000cm
  • Heavy orographic rainfall caused by a lift of the monsoon winds occurs in windward side of the hills
  • Funnelling effect causes a concentration of rain-bearing clouds in between mountains
• Seasons:
  • The Monsoon climate has three distinct seasons with varying weather conditions:
  • Hot dry season: lasts from March to mid-June with a sharp rise in temperatures, reaching 35°C on average during the day and up to 44°C in some regions. There is little rainfall, except for occasional thunderstorms, and coastal areas are not as hot due to sea breezes.
  • Rainy season: lasts from mid-June to September and is characterized by torrential rainfall throughout the country. Over 70% of the country’s annual rainfall occurs during this season.
  • Cold dry season: begins in October and lasts until February. Also known as the season of retreating monsoon, it is marked by falling temperatures and the retreat of the southwest monsoon winds from the Indian subcontinent. The winds blow from the northeast direction over the Bay of Bengal and bring some rainfall along the southeast coastal landmass of India in November and December. In the north, the Western Disturbances bring some rain and snow, which is important for the survival of winter crops.
• Forests:
  • Monsoon forests are also known as Tropical Monsoon Forests.
  • They are mostly deciduous trees, which shed leaves during the dry season to prevent transpiration losses.
  • There are two types of monsoon forests: moist deciduous (rainfall exceeds 150cm) and dry deciduous (rainfall less than 150cm).
  • Monsoon forests are made up of broad-leaf hardwood trees and are less dense with less diversity of species compared to equatorial rainforests.
  • Evergreen rainforests of the equatorial type can be found where rainfall exceeds 200-250cm, in southern Western Ghats, northeast forests, Andaman and Nicobar islands of India, and islands of southeast Asia.
  • Scanty rainfall areas have savanna-type grasslands with scattered trees.
  • Monsoon vegetation shows great variation from dense forests to thorny scrublands (savanna).
• Economy:
  • High population density in monsoon regions
  • Subsistence agriculture is the main type of crop cultivation
  • Shifting cultivation and plantation agriculture are also practised
  • Cereals like rice, wheat, maize, jute, sugarcane, and spices are cultivated in the plains of north India
  • Plantation crops like tea, coffee, rubber, and banana are found in the highlands of south and east India
  • Lumbering is an important activity in these regions
  • Forests yield durable hardwood like Teak, Sal, Acacia, Eucalyptus, Neem, Mango etc.
  • Bamboo is also an important source of timber.
• 

Desert Climate

• Desert regions are characterized by very little rainfall and scanty vegetation.
• The length of the growing period is limited to a small rainy season.
• The landscape of the region is devoid of trees and animals due to the lack of moisture and food.
• There are two types of deserts: hot deserts and mid-latitude deserts.
• Hot deserts – distribution:
  • Hot deserts are located on the western edges of the continents between latitudes 15 to 30 degrees north and south.
  • The Sahara desert is the largest hot desert, covering an area of 3.5 million square miles.
  • Other prominent hot deserts include the Great Australian Desert, Arabian desert, Kalahari desert, and Thar desert.
  • Hot deserts are also found in the Americas, including the Mohave, Sonoran, Californian, and Mexican deserts in North America and the Atacama or Peruvian desert in South America.
• Hot deserts – Temperature:
  • These deserts are some of the hottest places on earth and have high temperatures throughout the year.
  • They do not have a distinct cold weather season.
  • The average summer temperatures are always above 30 degrees centigrade.
  • The hottest temperature ever recorded was in Libya in 1922, where the temperatures rose as high as 57 degrees centigrade.
  • Cloudless skies, intense insolation, dry air, and a rapid rate of evaporation are the reasons for such high temperatures.
  • Coastal areas of these deserts have a relatively moderate climate due to the moderating influence of seas.
  • The interior regions experience extreme temperatures – hot summers and cold winters.
  • The diurnal temperature range is very high, with intense solar radiation during the day causing the temperature to rise and dropping below the mean temperature at night due to continuous loss of heat by radiation and absence of cloud cover.
  • The average diurnal range of temperatures is around 14 to 25 degrees centigrade.
  • Frost is a common occurrence during winter nights.
• Hot deserts – Precipitation:
  • Average annual precipitation in these regions is not more than 25 cm.
  • These deserts are located within the Sub-Tropical High-Pressure Belts, where air masses are descending, making it unfavourable for the formation of clouds and precipitation.
  • The prevailing Trade Winds do not allow any moisture-laden winds to blow over these regions from the sea.
  • The relative humidity decreases from 60% in the coastal areas to less than 30% in the interiors, increasing the rate of evaporation and reducing any chance of precipitation, making these regions of permanent drought.
  • The cold currents which flow along the west coasts of the continents have a desiccating effect on these deserts, reducing any chance of precipitation.
  • However, violent thunderstorms can cause convectional rainfall for shorter durations, which often have disastrous consequences in the form of landslides.
  • The Atacama desert is the driest region in the world, with an annual precipitation of less than 2 cm.
• Mid-Latitude deserts – distribution:
  • These desert are often situated on plateaux and are a part of continental interiors.
  • They include Gobi desert, Turkestan desert, Patagonian desert etc.
  • In India, Ladakh desert falls under this category.
• Mid-latitude deserts – climate:
  • The climatic conditions of these deserts are similar to hot deserts.
  • They are far away from the coast or blocked by high mountains, preventing moisture-laden winds from reaching them.
  • Average annual precipitation does not exceed 25 cm.
  • Occasional depression may bring light rainfall in winters and convectional rainfall during summers.
  • These regions have a greater range of annual temperatures than hot deserts due to continentality.
  • Winters experience freezing temperatures and strong cold winds.
  • Ice thaws during summers, causing floods in some places.
• Desert Vegetation:
  • All deserts have some form of vegetation
  • Vegetation lies dormant waiting for the irregular rains
  • Most common type of vegetation in hot and mid-latitude deserts is xerophytic or drought-resistant scrub
  • Important species include bulbous cacti, long-rooted wiry grasses, thorny bushes, and dwarf acacia
  • In some regions with abundant groundwater, clusters of date palms can be found in hot deserts
  • Vegetation is adapted to intense aridity
  • Soils are deficient in humus due to the absence of moisture
  • Shrub vegetation has a well-developed system of long roots to search for groundwater and minimize water loss
  • Foliage is hairy, waxy, or needle-shaped to minimize water loss through transpiration
  • Seeds have thick, tough outer surfaces to protect themselves when dormant, and germinate with rain.
• Life in the deserts:
  • Despite their inhospitable conditions, different types of human settlements have come up in these deserts
  • Primitive hunters and gatherers: tribes who do not cultivate crops or domesticate animals, such as the Bushmen of the Kalahari and Bindibu or Aborigines of Australia
  • Nomadic herdsmen: pursue a livestock economy, wandering through the deserts with their herds in search of water and green pastures, including Bedouins of Arabia, Tuaregs of Sahara, and Mongols of Gobi desert
  • Settled cultivators: survive close to rivers such as Nile in Egypt, Indus in Pakistan, Colorado in the USA, and Tigris-Euphrates in Iraq. They cultivate crops like wheat, barley, sugarcane, fruits and vegetables
  • Mining settlers: live in areas with natural resources, such as gold mines in Australia, diamond mines in Kalahari, copper mines in Chile, silver mines in Mexico, and oil in the Persian Gulf countries.
• 

Steppe Climate

• The term steppe refers to a region which is a semi-desert with a grassland or shrub vegetation.
• Steppes are intermediate regions, not receiving enough rainfall to support a forest but are also not as dry as a desert.
• Steppe Climatic region is also known as Temperate Grasslands.
• These grasslands are some of the most developed agricultural fields and are termed as grain baskets.
• Livestock ranching is another major activity carried out in these areas due to the availability of natural grasses.
• Distribution:
  • Steppes are located in continental interiors.
  • They are found in temperate latitudes and influenced by Westerly winds.
  • Steppes are vast grasslands without many trees.
  • They refer to the temperate grasslands of Eurasia, stretching over 2000 miles.
  • Different regions have their own names for steppes, including Prairies in North America, Pustaz in Hungary, Pampas in Argentina and Uruguay, Velds (High Veld) in South Africa, Downs in Australia, and Canterbury in New Zealand.
• Precipitation:
  • Average annual rainfall in steppes varies from 25 to 75 cm depending on the region.
  • The highest rainfall occurs in the spring season or just prior to the onset of summers.
  • In the northern hemisphere, this occurs in the months of June and July.
  • Winters bring occasional depressions with low precipitation (around 25 cm) and snowfall due to Westerlies.
  • In the southern hemisphere, steppes receive higher rainfall due to a larger influence of maritime weather.
• Temperature:
  • Steppes experience extremities in temperature due to continentality.
  • Summers are warm with average temperatures ranging from 18-20 degrees Celsius.
  • Winters are usually cold with occasional snowfall.
  • Steppes in the northern hemisphere have a very high annual range of temperatures.
  • In contrast, the steppes in the southern hemisphere have a moderate climate throughout the year due to maritime influence.
• Winds:
  • Prevailing winds in steppes are the Westerlies
  • Westerlies responsible for precipitation during winters
  • Local winds also impact weather, have different names:
  • Mistral: cold, dry wind in France
  • Loo: warm, dry wind in Gangetic plains
  • Sirocco: warm, dry wind in Sahara
  • Foehn: warm, dry wind in Alps
  • Chinook: hot, dry wind in North American Prairies
  • Chinook is a Katabatic wind, descends from Rocky mountains
  • It raises temperature by over 5 degrees centigrade in 20 minutes
  • It is useful for local agriculture as it melts snow, allows animals to graze on pastures.
• Vegetation:
  • Temperate grasslands are treeless, unlike savannas which have trees
  • Grass in temperate grasslands is shorter but fresher and more nutritious than savanna grass
  • Prairie soils are nutritious black earth soils
  • Grass is lean, thin, and scattered in temperate grasslands
  • This makes them ideal for large-scale livestock rearing or ranching
  • Grass grows throughout the year in temperate grasslands
  • Towards the poleward extension of prairies, there is a transitional zone of forests with conifers
  • Trees are planted around croplands in farmlands of steppes to shield them from strong winds.
• Economy:
  • Steppes have less animal diversity compared to savannas
  • Horses can be found in Eurasian steppes
  • Crop cultivation is extensively practised, especially in the prairies, using irrigation canals and mechanized cultivation over large tracts of land
  • Prairies are known as the granaries of the world, with wheat and maize as prominent crops
  • Livestock ranching is carried out on a large scale, aided by replacing tufted grass with more nutritious Lucerne or alfalfa grass
  • Steppes are the largest producers of dairy and other animal products in the world, with exports aided by containerized cargo and refrigerated ships
  • Nomadic herding is practised by natives such as Kazakhs and Kirghiz in the vast steppes of Eurasia
  • Various grassland regions are famous for different kinds of economic activities, including wheat cultivation, livestock ranching, sheep and cattle rearing, maize cultivation, sugar beet cultivation, wool production, and export of dairy and beef products.
• 

Mediterranean Climate (Western Margin Climate)

• The warm temperate western margin climate or the Mediterranean climate is found between 30o and 45o North and South of the Equator.
• This climate is witnessed in relatively fewer parts of the world and is almost entirely confined to the western margins of the continental landmasses.
• The basic cause of this climate is the seasonal shift of the wind belts.
• Distribution:
  • Central Chile,
  • California (around San Francisco),
  • The southwestern tip of Africa (around Cape Town),
  • Southern Australia (in southern Victoria and
  • Around Adelaide bordering St, Vincent, and Spencer Gulfs), and south-west Australia (Swanland).
• Climate:
  • The Mediterranean climate is characterized by very distinctive climatic features with dry, warm summers and wet, cold winters and local winds.
  • Dry, warm summers with off-shore Tradewinds:
    • Sun is overhead the Tropic of Cancer and Tropic of Capricorn
    • Westerlies belt shifted polewards
    • Rain-bearing tradewinds are off-shore
    • Regions are practically rainless in summers and remain dry
    • Intense heat and excessively warm days
    • Prolonged droughts are common in interiors
    • Relative humidity is generally low
    • Summer temperatures are relatively high
    • Highest temperatures are experienced away from the coast in the continental interiors of the Balkan peninsula, the Anatolian plateau, and the Mediterranean Middle East.
  • Wet, cold winters with on-shore Westerlies:
    • The Westerlies belt shifts equatorward in the winter months.
    • Mediterranean regions are under the influence of on-shore Westerlies.
    • These lands receive almost all of their precipitation during the winter months.
    • The rain comes in heavy downpours.
    • Floods are common in the months of September and October in Mediterranean Europe.
• Local winds:
  • The Mediterranean climatic region in Europe has many local winds due to the topography of the region.
  • The region is influenced by the Alps in the North, Sahara desert in the South, continental interiors in the East, and the open Atlantic in the west.
  • These create great differences in temperature, pressure, and precipitation.
  • The two most important local winds are Sirocco and Mistral.
  • Sirocco is a hot, dry, and dusty wind from the Sahara desert that blows into the Mediterranean Sea.
  • It occurs mostly during spring and lasts only for a few days.
  • Sirocco is associated with the depressions from the Atlantic ocean and withers vegetation and crops of the region.
  • Mistral is a cold wind from the north that rushes down the Rhone valley and is intensified by the funnelling effect in the valley.
  • In some extreme cases, the velocity of the Mistral wind is so high that trains can be derailed and trees are uprooted.
  • In winter, if the Mistral is frequent, the temperatures could go below the freezing point.
  • Other local winds include Bora, Tramontana, and Gregale.
• Natural Vegetation:
  • The vegetation of the Mediterranean region is not luxuriant, and trees are widely spaced with small broad leaves.
  • The growth is almost restricted to autumn and spring, and plants struggle against heat, dry air, excessive evaporation, and prolonged droughts.
  • Mediterranean vegetation is generally xerophytic or drought resistant.
  • There are three types of Mediterranean vegetation: evergreen forests, evergreen coniferous forests, bushes and shrubs, and grass.
  • Evergreen forests are open woodlands with evergreen oaks and cork oaks used for making wine-bottle corks.
  • Evergreen coniferous forests include various kinds of pines, firs, cedars, and cypresses and appear mostly in cooler highlands where droughts are less severe.
  • Bushes and shrubs are the most prominent type of Mediterranean vegetation, with low bushes growing in scattered clumps and often being thorny.
  • Grass is not suitable for animal farming because most of the rain comes during the cool season when growth is slow, and it is generally wiry and bunchy.
  • Cattle rearing is not an important occupation in the Mediterranean region.
• Economic Development:
  • The Mediterranean region is important for fruit cultivation, cereal growing, wine-making, and agricultural industries as well as engineering and mining.
  • The region is a net exporter of citrus fruits and a net importer of dairy products.
  • The region is known as the world’s orchard lands and produces a wide range of citrus fruits, including Sunkist oranges of California and Jaffa oranges of Israel.
  • Fruit trees in the region have long roots to draw water from depths during the long summer months.
  • The olive tree is the most typical of all Mediterranean cultivated vegetation, and many nut trees like chestnuts, walnuts, hazelnuts, and almonds are grown.
  • Other important fruits grown in the region include peaches, apricots, pears, cherries, plums, and figs.
  • Cereals, particularly wheat and barley, are the most important crops.
  • Sheep, goat, and cattle rearing are practiced in mountain pastures with cooler climates, and transhumance is widely practiced.
  • Viticulture is a specialty and tradition of the Mediterranean region, and regions bordering the Mediterranean Sea account for three-quarters of the world’s wine production.
• 

Warm Temperate Eastern Margin Climate

• Eastern margin climate is found between 20 and 35 N and S latitude
• Similar to the monsoonal climate with summer rain and dry winter weather
• Variations include:
  • China Type: found in most parts of China, a modified form of monsoonal climate
  • Gulf Type: found in the southeastern parts of the USA bordering the Gulf of Mexico, less pronounced but similar to China Type
  • Natal Type: found in southern hemisphere regions like New South Wales, Natal, and Parana-Paraguay-Uruguay basin, influenced by on-shore Tradewinds throughout the year
• Climate:
  • Warm, moist summer and cool, dry winter
  • Occasionally cold air from continental interiors brings down temperature to freezing point
  • Relative humidity high in mid-summer, but generally pleasantly warm
  • Rainfall is more than moderate, ranging between 60 cm to 150 cm
  • Uniform temperature distribution throughout the year
  • Rain comes from convectional sources or orographic rain in summer, and depressions in prolonged showers in winter
  • Local storms occur (e.g., typhoons, hurricanes)
  • Adequate rainfall for all agricultural purposes
  • Regions are densely populated
  • China Type:
    • Intense heating of continental interiors in summer attracts tropical Pacific air stream
    • South-East monsoon in the region
    • Intense high pressure over Siberia in winter
    • North-West Monsoon, bitterly cold and very dry
    • Little rain but considerable snow
    • Intense tropical cyclones called typhoons in late summer
  • Gulf Type:
    • Gulf-Atlantic regions of the USA
    • Similar to China type but less monsoonal
    • Warm Gulf stream and on-shore Tradewinds bring down temperature range
    • Heavy annual rainfall of around 59 inches
    • Increased rain by thunderstorms in summer and hurricanes in September and October
    • Violent tornadoes due to intense local heating
  • Natal Type:
    • Narrowness of continents and dominance of maritime influence eliminate monsoonal elements
    • South-East Tradewinds bring about more even distribution of rainfall throughout the year
    • Low annual range of temperature
    • Rain comes in prolonged showers
• Natural Vegetation:
  • Luxurious vegetation due to heavy rainfall
  • Perennial plant growth
  • Lowlands: evergreen broad-leaved forests and deciduous trees, similar to tropical monsoon forests
  • Highlands: various species of conifers such as pines and cypresses, which are important softwoods
  • Examples of vegetation in specific regions:
    • Eastern Australia: Eucalyptus
    • South-Eastern Brazil, eastern Paraguay, north-eastern Argentina: Parana pine, quebracho, wild yerba mate trees
    • Natal: palm trees
• Economic Development:
  • Temperate monsoon regions are located in the middle latitudes of the world.
  • These regions are highly productive due to adequate rainfall.
  • There are no prolonged droughts in these regions.
  • The cold season in these regions is relatively warm, allowing for a nearly continuous growing season.
  • The temperate monsoon regions are intensively tilled, making them the most cultivated regions in the world.
• Farming in Monsoon China:
  • Monsoon China has a population of almost one-third of the world’s population.
  • It is the world’s greatest rice-growing region and a third of the world’s rice is grown there.
  • The region has ideal conditions for paddy cultivation, with a warm climate, moderately wet throughout the year, and extensive lowlands with moisture-retentive alluvial soils.
  • The Chinese practice ‘wet-paddy’ cultivation which requires a huge population and endless hard labour.
  • Farming is usually on a subsistence basis, but progress has been made towards double and treble cropping, increasing the total rice production.
  • Sericulture has also been practised in the region, but it is now on a decline.
• Agriculture in the Gulf States:
  • Agriculture in the Gulf States of the USA is focused on corn, cotton, and tobacco.
  • Corn is the primary crop and is well-suited to the humid air, sunny summers, and heavy showers in the region.
  • The Gulf States account for more than half of the world’s corn production but exports very little.
  • Cotton is the most prominent cash crop in the region, and the climate is well-suited for its growth.
  • Fine quality cotton is also grown in well-irrigated dry areas.
  • Tobacco is another important crop, and the region is responsible for around half of the tobacco in the international trade.
  • The warm, humid atmosphere and well-drained soils in the Gulf States enable the successful growth of tobacco.
  • Boll-weevil is the most dreaded enemy of the Cotton Belt and responsible for the westward migration of the Cotton Belt.
• Crop cultivation in the eastern margins of the Southern Hemisphere:
  • Coastlands of Natal: dominant crop is cane sugar, followed by cotton and tobacco; maize is also cultivated for food and feed; natural pastures provide valuable forage for cattle and sheep.
  • South America: less rainfall; cattle and sheep are reared for meat, wool, and hides; mild winters allow for outdoor animal rearing.
  • Australia: heavy rainfall from moist Tradewinds in coastal districts with thick forests of giant eucalyptus trees; chief source of milk, butter, cheese, cotton, cane sugar, and maize.
• 

British Type Climate

• British-type climatic regions are under the permanent influence of the Westerlies all round the year.
• These are also regions of high cyclonic activity., typical of Britain and thus said to experience the British climate.
• This climate is also referred to as the cool temperate western margin climate or the North-west European Maritime Climate.
• Distribution:
  • Northern Hemisphere:
    • Covers Britain, North-West Europe, northern and western France, Belgium, the Netherlands, Denmark, western Norway, and north-western Iberia.
    • In North America, it is found mainly on the coastlands of British Columbia.
    • The Rockies prevent the on-shore Westerlies from reaching far inland.
  • Southern Hemisphere:
    • Experienced in southern Chile, Southern Australia, Tasmania, and most parts of New Zealand, especially in South Island.
    • The large expanses of water surrounding these regions have increased the maritime nature of the climate.
• Climate:
  • Moderately warm summers and fairly mild winters. Extremes of temperatures are not likely.
  • Adequate rainfall throughout the year.
  • Mean annual temperature range is usually 5 C – 15 C, which is comparatively small for such high latitudes.
  • Summers are not very warm and winters are abnormally mild due to the warming effect of the North Atlantic Drift and prevalence of the South-Westerlies.
  • Adequate rainfall throughout the year with a tendency towards a slight winter or autumn maximum from cyclonic sources.
  • Rain-bearing winds come from the west and hence western margins have the heaviest rainfall.
  • Four distinct seasons: summers are long and sunny, autumn is a roar of gusty winds, winter has cloudy skies, foggy and misty mornings, and many rainy days, followed by a dry and refreshing spring.
  • Most advanced regions of the world due to their favourable climate.
• Natural Vegetation:
  • The natural vegetation of this climatic type is the deciduous forest.
  • Trees shed their leaves in the cold season to protect against winter snow and frost.
  • Shedding begins in autumn and is scattered by winds.
  • Common temperate hardwood species include oak, elm, ash, birch, beech, hornbeam, and poplar.
  • Willows, alder, and aspen grow in wetter areas.
  • Deciduous trees occur in pure stands and have great commercial lumbering value.
  • Sparse undergrowth is useful in logging operations.
  • Deciduous hardwoods are excellent for fuel and industrial purposes.
  • In higher elevations, conifers replace deciduous trees as they can survive in lower temperatures, poorer soils, and higher altitudes.
• Economic Development:
  • In Britain, only 4% of the original forest is left. A very large part of the deciduous hardwoods has been cleared for fuel, timber or agriculture.
  • Lumbering in quite profitable in the region for the reasons mentioned above.
• Agriculture:
  • Due to high population density, all cereals, fruits, and root crops grown are used for home consumption
  • North West Europe practices extensive market gardening due to large urban populations and demand for fresh produce
  • Market gardening yields high returns due to soil fertility and good transport networks
  • Mixed farming is practiced with both arable and pastoral farming
  • Wheat is the most extensively grown cereal for home consumption, barley is grown for beer-making or whisky distilling
  • Cattle are the most important animals kept in mixed farms, with intensive dairying in ideal climate
  • Sheep rearing is done for wool and mutton, with the UK and New Zealand as major sheep areas
  • New Zealand accounts for 2/3 of the world’s mutton exports and 1/6 of wool exports
• Industrialization:
  • Machinery, chemicals, and textiles are the main industries in the region.
  • Denmark, Netherlands, and New Zealand have industries based on dairy products.
  • The region is highly industrialized, with Britain, France, and Germany having significant mineral resources and heavy industrialization.
  • The Ruhr region in Germany, Yorkshire, Manchester, and Liverpool regions in Britain are significant for their manufacturing industries.
• 

Taiga Climate (Coniferous Forests & Lumbering)

• Taiga Climate is also known as Cool Temperate Continental Climate, Siberian Climate, or Boreal Climate
• Found mainly in the Northern Hemisphere and absent in the Southern Hemisphere due to narrow land surface
• Koppen’s classification defines Taiga as D type climatic region
• Summer months are warm with temperature more than 10 degrees C
• Winter temperature can be less than 3 degrees C
• Distribution:
  • The climate stretches from 50 N to 70 N across central Canada, some parts of Scandinavian Europe, and most of central and southern Russia.
  • The climate is called “Sub-arctic climate” as it merges with the Arctic tundra of Canada and Eurasia.
  • The climate becomes less severe towards the south and merges into the temperate Steppe climate.
  • In the Southern Hemisphere, the Siberian climate is absent due to the narrowness of the continents in the high latitudes.
  • The winter severity is reduced in the Southern Hemisphere due to the strong oceanic influence.
• Temperature:
  • Extremely cold winters with temperatures ranging around -30°C to -40°C
  • Cool and brief summers
  • Brief and transitional spring and autumn
  • Annual range of temperature is very high, almost 50°C to 60°C
  • Lakes and rivers are frozen
  • Northerly polar winds such as Blizzards of Canada and Buran of Eurasia blow violently
  • Siberian climatic regions are sparsely populated
• Precipitation:
  • Maritime influences are nearly absent in the interiors
  • Annual precipitation is low, generally around 38cm to 63cm
  • Well distributed throughout the year, with a summer maximum from convectional rain when the continental interiors are heated
  • Winter precipitation is in the form of snow
• Natural Vegetation:
  • The region is dominated by evergreen coniferous forests.
  • The four major species of coniferous forests found in the region are pine, fir, spruce, and larch.
  • The taiga in Siberia is the greatest single band of coniferous forest in the world.
  • Commercial Value:
    • Coniferous forests have huge commercial value due to their uniformity, straight growth, and moderate density.
    • Conifers are evergreen, which allows them to survive in the sub-arctic climate with low temperatures.
    • Conifers have conical shapes and sloping branches that prevent snow accumulation and offer little grip to the winds.
    • The leaves of the evergreen forests are small, thick, leathery, and needle-shaped to check excessive transpiration.
    • The undergrowth in the region is sparse due to poor podzolized soils, low temperatures, and absence of direct sunlight.
    • Coniferous forests are also found in regions of high altitude and reduced temperatures, such as the Himalayas.
• Economic Development:
  • Coniferous forests in northern hemisphere are underdeveloped.
  • Most of the forests are untouched and inaccessible.
  • Lumbering is the predominant occupation in accessible areas.
  • Agriculture is limited due to long, cold winters and frozen soils.
  • Hunting, trapping, and fishing are common activities.
  • Trapping is important for fur-bearing animals such as muskrat, ermine, mink, silver fox, squirrels, otters, bears, sables, lynxes, martens, and foxes.
  • Fur farms have been established in Canada for a regular supply of furs.
  • Lumbering is the most important occupation of the Taiga climate.
  • Trees are felled for saw-milling, paper and pulp industry, fuel, and industrial raw material.
  • Saw-milling processes logs into various constructional woods.
  • Timber is pulped for papermaking and newsprint.
  • Softwoods are not used as fuel due to industrial uses.
  • Timber has various industrial uses including furniture, matches, wood-carvings, toys, crates, and packing cases.
  • Factors favorable for Lumbering in Siberian Climate:
    • Coniferous forests occur in pure stands, making felled timber more commercially valuable and saving time and money
    • Lumbering replaces unproductive agriculture in high latitudes
    • Lumbering is carried out in winter when tree sap stops flowing and snow makes logging and haulage easier
    • Logs are transported via rivers to downstream sawmills, but in Siberia, all rivers drain polewards into the Arctic Ocean
    • Cheap hydro-electricity from mountainous uplands in North America and Europe drives sawmills and helps the lumbering industry.
• 

Laurentian Climate

• The Cool Temperate Eastern Margin climate is also known as the Laurentian climate.
• It is the intermediate between the British and Siberian types of climates.
• Distribution:
  • It is found only in two regions and only in the northern hemisphere.
  • The climate has features of both the continental and the maritime climates.
  • North American region: One region is north-eastern North America including eastern Canada, north-east USA, and Newfoundland.
  • Asiatic region: The other region is the eastern coastlands of Asia, including North China, eastern Siberia, Manchuria, Korea and northern Japan.
  • The climate is totally absent in the southern hemisphere because only a small section of continental landmass extends south of the latitude of 40 S.
  • The only possible regions are in eastern Patagonia.
  • But the Southern Andes blocks the Westerlies and the region is subjected to aridity rather than continentality.
  • It is a rain-shadow region and its annual precipitation is not more than 10 inches.
• Temperature:
  • Cold, dry winters and warm, wet summers.
  • Snowfall to a significant depth during winter, with temperatures dropping well below freezing point.
  • Summers are warm as in the tropics and are moderated by the cooling effects of off-shore cold currents from the Arctic.
• Precipitation:
  • Rain falls throughout the year with a distinct summer maximum.
  • Two-thirds of the annual precipitation is in summer, while winters are dry and cold with westerlies blowing out from the continental interiors.
• North American region:
  • Uniformity in annual precipitation due to the Atlantic influence and that of the Great Lakes.
  • Warm Gulf Stream increases the moisture content of easterly winds from the open Atlantic.
  • Prevailing Westerlies carry depressions over the Great Lakes towards eastern regions causing wet conditions, especially in winter.
  • Newfoundland experiences more drizzles than any other part of the world.
  • In summer, the Westerlies bring fewer depressions and extend their continental influence to the coast.
• Asiatic region:
  • Distribution of precipitation is less uniform in the Asiatic region.
  • Winters are very cold and dry while summers are warm and exceptionally wet.
  • Rainfall regime resembles the tropical monsoon type in India where the rainfall is concentrated in the three summer months.
• Climate in Japan:
  • Modified by its insularity and the meeting of warm (Kuroshio) and cold (Oyashio) ocean currents.
  • Adequate rainfall from both the South-East Monsoon in summer and the North-West monsoon in winter.
  • Rainfall is more evenly distributed with two maxima: the Plum rain in June and the Typhoon Rain in September.
• Natural Vegetation:
  • The predominant vegetation in this climate is cool temperate forests.
  • The heavy rainfall, the warm summers and the damp air from fogs all favour the growth of trees.
  • Forest tend to be coniferous north of the 50 N latitude.
  • South of this latitude, deciduous forests is seen.
• Economic Development:
  • Lumbering and associated industries (timber, paper, and pulp) are important in the region, especially in the Asiatic region.
  • Agriculture is less important due to long and severe winters.
  • Fishing is a major economic activity in the Laurentian and Japanese climatic regions.
  • Fishing:
    • Newfoundland is one of the world’s largest fishing grounds, with fish of all types and sizes breeding there.
    • Over-fishing is a growing problem, and conservation measures are being taken.
    • The North-West Pacific surrounding Japan is another major fishing area of the world.
    • Fishing is dominant in Japan due to its lack of natural resources, non-agricultural land, and rich plankton breeding grounds.
    • Fishing has become more scientific, with heavy hauls, high returns, and increased annual fish yield through mechanisation.
• 

Polar Climate (Tundra & Ice Caps)

• Polar climate has cold climatic conditions all through the year.
• Koppen classified Polar Climate as E type in his climatic classification.
• According to Koppen the summer temperature in this region is less than 10 degrees. He further divided the polar climate as Polar Tundra and Polar Ice Caps.
• Distribution:
  • Northern Hemisphere:
    • Polar climate north of the Arctic Circle
    • Ice-caps in Greenland and high-latitude regions
    • Lowlands with tundra vegetation (ice-free for few months)
    • Coastal strip of Greenland, barren grounds of northern Canada and Alaska, Arctic seaboard of Eurasia
  • Southern Hemisphere:
    • Antarctica is the greatest single stretch of ice-cap
    • Layers of permanent ice
• Temperature:
  • Tundra or polar climate has a very low mean annual temperature
  • Only four months have a temperature above freezing point
  • Interiors are much colder than the coastal regions
  • Winters are long and very severe, summers are cool and brief
  • Weeks of continuous darkness occur beyond the Arctic and Antarctic circles
• Precipitation:
  • Precipitation is mainly in the form of snow, falling in winter and being drifted by the blizzards
  • Convectional rainfall is generally absent because of the low rate of evaporation and the lack of moisture in the cold polar air
  • In summer, there is a maximum and the precipitation is in the form of rain or sleet
  • Cyclones are felt in the coastal areas and there is a tendency towards a winter maximum.
• Natural Vegetation:
  • Tundra vegetation is limited due to severe environmental conditions.
  • Lack of heat and energy is the biggest hindrance to plant growth.
  • Growing season is less than three months and there are no trees in tundra.
  • Vegetation is limited to mosses, lichens, and sedges.
  • In sheltered areas, stunted birches, dwarf willows, and undersized alders grow.
  • During brief summers, berry bushes and Arctic flowers bloom, brightening up the landscape.
  • Arctic prairies are formed due to the short-lived vegetation in the summer.
• Human Activities:
  • Human activities in the polar regions are largely confined to the coast.
  • The high altitude plateaus and mountains are uninhabitable as these are permanently snow-covered.
  • The people lead a semi-nomadic life.
  • Eskimos live in Greenland, northern Canada, and Alaska.
  • Earlier they lived as hunters, fishers, and food-gatherers but in recent years they have started settling in permanent huts.
  • During winter, they live in compact igloos and in summer they pitch portable tents of skins by the side of streams.
  • Their food is derived from fish, seals, walruses and polar bears.
  • In Eurasian tundra, other nomadic tribes like Lapps of northern Finland and Scandinavia, the Samoyeds of Siberia(from the Ural Mountains and the Yenisey Basin), the Yakuts from the Lena basin, the Koryaks and Chuckchi of north-eastern Asia live.
  • They wander with their herds of reindeer across the Eurasian tundra where there are pastures.
  • In USSR, large farms have been established for raising reindeer and for breeding fur-bearing animals.
• Importance and Recent Development of the Arctic Region:
  • The Arctic region was once regarded as completely useless to mankind.
  • But now the economic importance of the region has been recognized.
  • Because of the discovery of minerals, new settlements have come up in the region.
  • New railway lines have been constructed to bring shipments of ores mined to the major industrial districts.
  • Ports have been established in the Arctic seaboard of Eurasia. Hence it has become possible to ship timber and fur from Siberia.
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