- They lie in the interiors of the continents.
- Lie in the Westerly wind belt [mid-latitudes or temperate region].
- Grasslands are practically treeless due to continentality [deep within the interiors of the continents where rain bearing winds don’t reach].
- In Eurasia, they are called the Steppes, and stretch eastwards from the shores of the Black Sea to the foothills of the Altai Mountains. [2,000 miles long belt].
- Climate is continental with extremes of temperature.
- Temperatures vary greatly between summer and winter.
- The summers are hot and the winters are cold.
- Summers are very warm, over 18 – 20° C.
- The steppe type of climate in the southern hemisphere is never severe.
- The average rainfall may be taken as about 45 cm, but this varies according to location from 25 cm to 75 cm.
- The heaviest rain comes in June and July (late spring and early summer).
- Most of the winter months have about an 2.5 cm of precipitation, brought by the occasional depressions of the Westerlies and coming in the form of snow.
- The maritime influence in the southern hemisphere causes more rainfall.
- Greatest difference from the tropical savanna is that steppes are practically treeless and the grasses are much shorter.
- Grasses are tall, fresh and nutritious. This is typical of the grass of the wheat-lands in North America, the rich black earth or chernozem areas of Russian Ukraine and the better watered areas of the Asiatic Steppes.
- Where the rainfall is light or unreliable, or the soil is poor, as in the continental interiors of Asia the short steppe type of grass prevails.
- The grasses are not only shorter but also wiry [lean, tough] and sparse [thinly dispersed or scattered].
- These areas are less suitable for arable farming and are used for some form of ranching as in the High Plains of U.S.A.
- The growth of grasses is not abruptly checked by summer droughts or winter cold.
Warm Temperate Western Margin
- Entirely confined to the western portion of continental masses, between 30° and 45° north and south of the equator.
- The basic cause of this type of climate is the shifting of the wind belts.
- Mediterranean Sea has the greatest extent of this type of ‘winter rain climate’, and gives rise to the name Mediterranean Climate.
- The best developed form of this climatic type is found in central Chile.
Other Mediterranean regions include
- California (around San Francisco),
- the south-western tip of Africa (around Cape Town),
- southern Australia, and south-west Australia (Swanland).
Warm Temperate Western Margin
Clear skies and high temperatures; hot, dry summers and cool, wet winters.
- Mean annual precipitation ranges from 35 – 90 cm.
- Temperature of warmest month greater than or equal to 10⁰ C. Temperature of coldest month is less than 18⁰ C but greater than –3⁰ C
- Climate is not extreme because of cooling from water bodies.
- Trees with small broad leaves are widely spaced and never very tall.
- The absence of shade is a distinct feature of Mediterranean lands.
- Plants are in a continuous struggle against heat, dry air, excessive evaporation and prolonged droughts. They are, in short xerophytic [drought tolerant], a word used to describe the drought-resistant plants in an environment deficient in moisture.
- The Mediterranean lands are also known as the world’s orchard lands.
- A wide range of citrus fruits such as oranges, lemons, limes, citrons and grapefruit are grown.
- The fruit trees have long roots to draw water from considerable depths during the long summer drought.
- The thick, leathery skin of the citrus fruits prevents excessive transpiration.
- The long, sunny summer enables the fruits to be ripened and harvested.
- The Mediterranean lands account for 70 per cent of the world’s exports of citrus fruits.
- The olive tree is probably the most typical of all Mediterranean cultivated vegetation.
- Olive oil extracted is a valuable source of cooking oil in a region deficient in animal fat.
- Besides olives, many nut trees like chestnuts, walnuts, hazelnuts and almonds are grown and the nuts picked as fruits or for the chocolate industry.
- Viticulture is by tradition a Mediterranean occupation.
- Regions bordering the Mediterranean Sea account for three-quarters of the world’s production of wine.
- Some 85 percent of grapes produced, go into wine.
- The long, sunny summer allows the grapes to ripen.
Warm Temperate Eastern Margin
Warm Temperate Eastern Margin
- China Type
- Natal Type
- Gulf Type
Warm Temperate Eastern Margin
- Temperate Monsoon or China Type climate is observed in most parts of China. The climate is also observed in southern parts of Japan.
- Found in south-eastern U.S.A., bordering the Gulf of Mexico where continental heating in summer induces an inflow of air from the cooler Atlantic Ocean.
- Natal type is found in in New South Wales (Australia), Natal (South Africa), Parana-Paraguay-Uruguay basin (South America). Natal type is different from temperate monsoon or China type as it receives rainfall from on-shore Trade Winds all the year round.
Climate – Temperature
- Characterized by a warm moist summer and a cool, dry winter (one exception: winters are also moist in Natal Type).
- The mean monthly temperature varies between 4° C and 25° C and is strongly modified by maritime influence.
- Occasionally, the penetration of cold air (Polar Vortex) from the continental interiors may bring down the temperature to freezing point.
- Though frosts are rare they occasionally occur in the colder interiors.
Climate – Rainfall
- Rainfall is more than moderate, anything from 60 cm to 150 cm.
- This is adequate for all agricultural purposes and hence supports a wide range of crops.
- Areas which experience this climate are very densely populated.
- There is the fairly uniform distribution of rainfall throughout the year.
- Rain comes either from convectional sources or as orographic rain in summer, or from depressions in prolonged showers in winter.
- In summer, the regions are under the influence of moist, maritime airflow from the subtropical anticyclonic cells.
- Local storms, e.g. typhoons (tropical cyclones), and hurricanes, also occur.
- In winter, there is intense pressure over Siberia and the continental polar air stream flows outwards as the North-West Monsoon, bitterly cold and very dry.
- There is little rain but considerable snow on the windward slopes.
- Another climatic feature associated with the China type of climate in southern China is the occurrence of typhoons.
- Intense heating within interiors (Tibet, desert region) sets up a region of low pressure in summer attracting tropical Pacific air stream (South-East Monsoon).
- Monsoon does not ‘burst’ as suddenly, nor ‘pour’ as heavily as in India.
- Typhoons form mostly in late summer, from July to September.
- Monsoonal characteristics are less intense compared to China type.
- There is no complete seasonal wind reversal.
- Hurricanes occur in September and October.
- The narrowness of the continents and the dominance of maritime influence eliminate the monsoonal elements.
- The South-East Trade Winds bring about a more even distribution of rainfall throughout the year
- Supports a luxuriant vegetation.
- The lowlands carry both evergreen broad-leaved forests and deciduous trees [hardwood].
- On the highlands, are various species of conifers such as pines and cypresses which are important softwoods.
- Perennial plant growth is not checked by either a dry season or a cold season.
Cool Temperate Western Margin
- Moderately warm summers and fairly mild winters.
- Rainfall occurs throughout the year with winter maxima.
- The mean annual temperatures are usually between 5° C and 15° C.
- Winters are abnormally mild. This is because of the warming effect brought by warm North Atlantic Drift.
- Sometimes, unusual cold spells are caused by the invasion of cold polar continental air (Polar Vortex) from the interiors.
Climate – Precipitation
- The British type of climate has adequate rainfall throughout the year with a tendency towards a slight winter maximum (due to frontal cyclones).
- Western margins have the heaviest rainfall due to westerlies.
- Relief can make great differences in the annual amount. This is particularly significant in New Zealand where the western margins are subjected to heavy orographic rainfall whereas the eastern Canterbury plains receive comparatively less rainfall due to rain-shadow effect.
- As in other temperate regions there are four distinct seasons.
- Winter is the season of cloudy skies, foggy and misty mornings, and many rainy days from the passing depressions.
- Spring is the driest and the most refreshing season when people emerge from the depressing winter to see everything becoming green again.
- This is followed by the long, sunny summer.
- Next is the autumn with the roar of gusty winds; and the cycle repeats itself.
- This type of climate with its four distinct seasons is something that is conspicuously absent in the tropics.
- The natural vegetation of this climatic type is deciduous forest.
- The trees shed their leaves in the cold season.
- This is an adaptation for protecting themselves against the winter snow and frost.
- Shedding begins in autumn, the ‘fall’ season.
- Some of the common species include oak, elm, ash, birch, beech, and poplar.
- In the wetter areas grow willows (Light weight cricket bats are made from willows. In India willows are found in Kashmir).
- Higher up the mountains in the Scandinavian highlands, the Rockies, southern Andes and the Southern Alps of New Zealand, the deciduous trees are generally replaced by the conifers which can survive a higher altitude, a lower temperature and poorer soils.
Cool Temperate Eastern Margin
Cool Temperate Eastern Margin
- Intermediate type of climate between the British Type Climate (moderate) and the Taiga Type Climate (extreme) of climate.
- It has features of both the maritime and the continental climates.
- Characterized by cold, dry winters and warm, wet summers.
- Winter temperatures is below freezing-point and snow fall is quite natural.
- Summers are as warm as the tropics (~25 °C).
- Rainfall occurs throughout the year with summer maxima [easterly winds from the oceans bring rains]
- Annual rainfall ranges from 75 to 150 cm [two – thirds of rainfall occurs in the summer].
- Dry Westerlies that blow from continental interiors dominate winters
- The predominant vegetation is cool temperate forest.
- The heavy rainfall, the warm summers and the damp air from fogs, all favor the growth of trees.
- Forest tend to be coniferous north of the 50°N latitude.
- In the Asiatic region (eastern Siberia and Korea), the coniferous forests are a continuation of the great coniferous belt of the taiga.
- Found only in the northern hemisphere [due to great east-west extent. Absent in the southern hemisphere because of the narrowness in the high latitudes].
- Experienced in the regions just below Arctic circle.
- On its poleward side, it merges into the Arctic tundra.
- The climate fades into the temperate Steppe climate.
- Summers are brief and warm reaching 20-25 °C whereas winters are long and brutually cold – always 3040 °C below freezing.
- Annual temperature range of the Siberian Climate is the greatest [Almost 50-60 °C in Siberia].
- Some of the lowest temperatures in the world are recorded in Verkhoyansk (68°N. 113°E) where -67 °C was once recorded.
- In North America, the extremes are less severe, because of the continent’s lesser east-west stretch.
- All over Russia, nearly all the rivers are frozen. In normal years, the Volga is ice-covered for about 150 days.
- Occasionally cold, northerly polar local winds such as the blizzards of Canada and buran of Eurasia blow violently.
- Permafrosts [a thick subsurface layer of soil that remains below freezing point throughout the year] are generally absent as snow is a poor conductor of heat and protects the ground from the severe cold above.
- Maritime influence in the interiors is absent.
- Frontal disturbances might occur in winter.
- Typical annual precipitation ranges from 38 cm to 63 cm.
- It is quite well distributed throughout the year, with a summer maxima
[convectional rain in mid-summer – 15 °C to 24 °C]
- In winter the precipitation is in the form of snow, as mean temperatures are well below freezing all the time.
- The predominant vegetation is evergreen coniferous forest.
- The conifers, which require little moisture are best suited to this type of sub-Arctic climate.
- The greatest single band of the coniferous forest is the taiga (a Russian word for coniferous forest) in Siberia.
- In Europe the countries that have a similar type of climate and forests are Sweden and Finland.
- There are small amounts of natural coniferous forest in Germany, Poland, Switzerland, Austria and other parts of Europe.
- In North America, the belt stretches from Alaska across Canada into Labrador.
Tundra Type of Climate
- Found in regions north of the Arctic Circle and south of Antarctic Circle.
- The ice-caps are confined to highlands and high latitude regions of Greenland and Antarctica.
- In the southern hemisphere, Antarctica is the greatest single stretch of icecap (10,000 feet thick).
- The lowlands – coastal strip of Greenland, the barren grounds of northern Canada and Alaska and the Arctic seaboard of Eurasia, have tundra climate.
- The tundra climate is characterized by a very low mean annual temperature.
- In mid-winter temperatures are as low as 40 – 50 °C below freezing.
- Summers are relatively warmer.
- Normally not more than four months have temperatures above freezing-point.
- Within the Arctic and Antarctic Circles, there are weeks of continuous darkness (Rotation and Revolution).
- The ground remains solidly frozen and is inaccessible to plants.
- Frost occurs at any time and blizzards, reaching a velocity of 130 miles an hour are not infrequent.
- Precipitation is mainly in the form of snow and sleet.
- Convectional rainfall is generally absent.
- There are no trees in the tundra.
- Lowest form of vegetation like mosses, lichens etc. are found here and there.
- Climatic conditions along the coastal lowlands are a little favorable.
- Coastal lowlands support hardy grasses and the reindeer moss which provide the only pasturage for reindeers.
- In the brief summer, berry-bearing bushes and Arctic flowers bloom.
- In the summer, birds migrate north to prey on the numerous insects which emerge when the snow thaws.
- Mammals like the wolves, foxes, musk-ox, Arctic hare and lemmings also live in tundra regions.
- Penguins live only in Antarctic regions.