Category: Geography

Major crops of Tamil Nadu

Agriculture is and continues to be an important sector of Tamil Nadu’s economy. Around 60% of the total population of the state is engaged directly or indirectly in agriculture and its allied sectors. Tamil Nadu has around seven agro-climatic conditions and different soil conditions. That is suitable for the growth of Food crops, Species, Horticulture, Medicinal, and Aromatic plants.

But altogether, the major crop of Tamil Nadu is Paddy, millet, a variety of Pulses, different oil seeds, and Sugarcane. Also, different cash crops and tea plantations are also there.

Paddy

It is the most important staple food crop of Tamil Nadu. The major variety of paddy grown in Tamil Nadu is Ponni and Kichadi.

Rice cultivation in the state is 3 Million Hectares. Paddy cultivation is concentrated in Thanjavur, Tiruvarur, Tiruvallur, Kancheepuram, Villupuram, Cuddalore, and Tirunelveli districts.

Tamil Nadu Ranks is third in India. The Cauvery delta of Thanjavur district (Undivided) is the major rice production region of Tamil Nadu. As a result, the Cauvery delta is called the Granary of Tamil Nadu.

Millets

Millets are stable food for 1/3 of the population of Tamil Nadu. Major millets are Sorghum/Jowar (Cholam), Ragi (Kezhvaragu), and Bajra (Kambu).

Millets are grown in drier areas as well as coastal plains. Sorghum is cultivated in the Coimbatore plateau and Kambam Valley.

Ragi is grown in cultivated Dharmapuri, Vellore, Coimbatore, and Cuddalore districts. Bajra is grown in Ramanathapuram, Tirunelveli, Karur, Perambalur and Salem Districts.

India observed 2018 as the National Year of Millets.

FAO decided to observe 2023 as the International Year of Millets.

Pulses

Pulses are the main source of protein in India for the Vegetarian Population. Major pulses grown in India are Bengal Gram, Black Gram, Green Gram, Cow Pea, and Horse Gram.

Pulses are grown mostly in drier regions with or without irrigation. A mild Cool Climate and low to moderate rainfall are optimal for Pulse cultivation.

It also serves as excellent fodder for animals. Pulses are grown in almost all the districts of Chennai, Nilgiris, and Kanyakumari.

Coimbatore tops in the production of Bengal Gram. Vellore and Kanyakumari district’s products are Red Gram.

Tiruvarur, Nagapattinam, and Thoothukudi districts are principal producers of green gram and black gram.

Horse gram is widely cultivated in Dharmapuri and Krishnagiri districts.

National Project On Organic Farming

To promote organic farming a central scheme named National Project on Organic Farming. The scheme provides financial assistance through a capital investment subsidy scheme.

Oil Seeds

Oilseeds grown in Tamil Nadu are Groundnut, gingelly, castor, coconut, sunflower, and mustard. The oil is used for cooking.

Industrial applications of oil are used for Lubrication and making Varnish, Soaps, Candle, cosmetics, pharmaceuticals,

Groundnut is a major oilseed of Tamil Nadu. Groundnut cultivation is concentrated in Vellore, Tiruvannamalai, Villupuram, Salem, and Pudukottai districts.

Groundnut is also grown in Dharmapuri, Cuddalore, Perambalur, and Madurai. Erode, Ramanathapuram, Sivagangai, and Virudhunagar districts are minor producers.

Coconut which is also used to produce Oil is grown in Coimbatore, Thanjavur, and Kanyakumari districts.

Sugarcane

The major cash crop of Tamil Nadu is Sugarcane. It needs high temperatures and heavy rainfall.

Sugarcane grows well in tropical regions. Tiruvallure, Kancheepuram, Vellore, Cuddalore, Tiruchirapalli, Coimbatore, Erode, and Tirunelveli are major sugarcane-producing districts.

Cotton

Cotton is a fibre crop and it is also a cash crop. It requires black soil, long frost-free conditions, and warm and humid weather. It needs Humid weather in the early stages and hot, dry weather during the harvest period.

Cotton is mostly cultivated in the Coimbatore plateau and Vaigai-Vaippar river basins. It is also cultivated in Madurai, Ramanathapuram, Virudhunagar, Tirunelveli, Thoothukudi, Salem, and Dharmapuri districts.

Plantation crops

Major plantation crops of Tamilnadu are Tea, Coffee, Cashew, rubber, and Cinchona. In Tea production, Tamilnadu ranks second in area and production. First in tea production in Assam.

Tea plantations are found in the Hills of Nilgiris and Coimbatore. The Nilgiris is an important region for tea plantations.

Coffee plants are grown in the hills of Western and Eastern Ghats. Coffee plantations are found in the hilly slopes of the Dindigul, Madurai, Theni, and Salem districts.

Coffee plantations are also found minor on the slopes of Yercaud, Kolli Hills, and Kodaikanal. Tamil Nadu is second in coffee production in India. The first is Karnataka.

Rubber plantation is an important Plantation crop, concentrated in the Kanyakumari district. Pepper is another plantation crop that needs warm and wet slopes, so it is grown in the Eastern and Western Ghats of Tamil Nadu.

Cashew is largely cultivated in the Cuddalore district. Cinchona is planted at heights varying from 1060 to 1280 metres in Anaimalai Hills.

Cardamom estates are found in the hills of Madurai Regions at an elevation of 915 to 1525 metres.

TANTEA – (Tamil Nadu Tea Plantation Corporation Limited)

It is one of the largest Black Tea Producer in India with High-quality clonal tea. With a Plantation that spread over 4500 Hec.

Tamil Nadu Dairy Development Corporation Ltd

Tamil Nadu Dairy Development Corporation Ltd was transformed into Aavin that is Tamil Nadu Co-operative Milk Producers Federation Limited.

Conclusion

The major crops grown in Tamilnadu are rice, ragi, maize, pulses, sugarcane, etc.

Inversion of temperature in Geography

Usually, the temperature decreases as the elevation increases. It is known as the Normal Lapse Rate.

Sometimes, this situation is reversed and the Normal Lapse Rate is inverted. It is called Inversion of Temperature in Geography.

It is the rate at which an atmosphere variable, the normal temperature in the atmosphere falls with altitude. A lapse in the sense is a gradual fall. That is in the dry air, the adiabatic lapse rate is 9.8 °C/km. It refers to the vertical component of the spatial gradient of temperature. This concept is mostly applied to the earth’s troposphere.

The Temperature inversion is also known as Thermal Inversion. It is a reversal of the behaviour of temperature in the Troposphere. In which the layer of cool air at the surface is overlaid by a layer of warmer air. The inversion is mostly of short duration and quite common.

“The ideal situation for inversion is long winter night with clear skies and still air.”

The day’s heat radiated off during the night. And during the early morning hours, the earth is cooler than the air above it. In polar areas, the temperature inversion is normal throughout the years.

Surface Inversion

The surface inversion promotes stability in the atmosphere’s lower layers. Then the lower strata of the atmosphere are filled with smoke and dust. This smoke and dust get collected under the inversion layer and spread horizontally.

During the Winter, the dense fogs in the morning are common. It lasts for a few hours until the sun warms the earth.

Air Drainage

The Dense fog also occurs in mountains and hills because of the Air Drainage. Then the cold air from the mountains and hills, which are produced at the night flows under the effect of gravity.

The cold air is heavy and dense. It acts like water and flows down the slope to pile up deeply in valley bottoms with warm air above. This phenomenon is called Air drainage and it protects plants from frost damage.

The harmful effect of temperature inversions

May result in deadly smog concentrations. When it lasts for several days, it may cause a build-up of pollution. When this pollution is prolonged, it severely affects the health of livings beings.

Conclusion

This article is written on the topic ‘temperature inversion upsc‘. This post is referred to the Ncert Geography book.

FAQ

What is DALR?

It is the rate at which the temperature of unsaturated air, becomes saturated and behaves like dry air. DALR is almost 3°C/1000 feet

Distribution of Temperature

The global distribution of temperature can well be understood by studying the temperature distribution in January and July. The temperature distribution is generally shown on the map with the help of isotherms.

Isotherms geography

The Isotherms are lines joining places having an equal temperature. In general, the effect of the latitude on temperature is well pronounced on the map, as the isotherms are generally parallel to the latitude.

The deviation from this general trend is more pronounced in January than in July, especially in the northern hemisphere. In the northern hemisphere, the land surface area is much larger than in the southern hemisphere.

Hence, the effects of landmass and the ocean currents are well pronounced. In January the isotherms deviate to the north over the ocean and to the south over the continent.

This can be seen in the North Atlantic Ocean. The presence of warm ocean currents, Gulf Stream, and North Atlantic drift, make the Northern Atlantic Ocean warmer, and the isotherms bend towards the north.

Over the land, the temperature decreases sharply and the isotherms bend towards the south in Europe. It is much pronounced in the Siberian plain. The mean January temperature along 60° E longitude is minus 20° C both at 80° N and 50° N latitudes.

The mean monthly temperature for January is over 27° C, in equatorial oceans over 24° C in the tropics and 2° C – 0° C in the middle latitudes and –18° C to –48° C in the Eurasian continental interior.

The effect of the ocean is well pronounced in the southern hemisphere. Here the isotherms are more or less parallel to the latitudes and the variation in temperature is more gradual than in the northern hemisphere.

The isotherm of 20° C, 10° C, and 0° C runs parallel to 35° S, 45° S and 60° S latitudes respectively. In July the isotherms generally run parallel to the latitude. The equatorial oceans record warmer temperatures, more than 27°C.

Over the land, more than 30°C is noticed in the subtropical continental region of Asia, along the 30° N latitude. Along the 40°, N runs the isotherm of 10° C and along with the 40° S, the temperature is 10° C.

The highest range of temperature is more than 60° C over the north-eastern part of the Eurasian continent. This is due to continentality. The least range of temperature, 3°C, is found between 20° S and 15° N.

Horizontal and vertical distribution of temperature

Horizontal distribution

The distribution of temperature across the latitudes of the surface of the earth is called Horizontal distribution. The most basic horizontal temperature variation is the decrease in air temperature slowly from the equator towards the pole.

Vertical distribution

This is the distribution of temperature in the different layers of the atmosphere at the different latitudes from the earth’s surface. The temperature slowly decreases with elevation (Increase in Height).

This vertical distribution of temperature, also the pressure, density, and composition of the atmosphere constitute the atmospheric structure. The decrease in temperature with an increase in height is because the air cools as it expands into lower pressure regions, but this does not happen everywhere.

This distribution is characterized by the vertical temperature gradient γ, which is expressed in degrees per 100 m. In the troposphere, the temperature decreases with height at an average rate of 0.6° per 100 m—that is, γ = 0.6°/100 m.

That is the average rate of temperature decrease upward in the troposphere is about 6 C per km, extending to the tropopause.

Factors controlling temperature distribution

Latitude, Distribution of Land and Water, Prevailing Winds, Ocean Currents, distance from the sea, altitude, etc.

Heating and cooling of atmosphere

The heating and cooling of the atmosphere happen in the atmosphere in different ways. The earth gets heated due to insolation. Then it transmits the heat using the long waveform to its nearest layer of the atmosphere.

The Air which is in contact with land gets heated slowly. Also, the upper layers of the atmosphere get heated by the lower layers. This process is called Conduction.

Conduction

The Conduction takes place when two bodies of unequal temperature get in contact with each other. There occurs a flow of energy between them, in the direction from warmer to cooler body.

This transfer of energy takes place until the temperature between two bodies becomes equal or their contact is broken. Conduction is an important process in heating the lower layers of the atmosphere.

Advection vs Convection Upsc

Convection

The Air, which is in contact with the earth, rises above vertically due to heating. In heated Air is in the form of current and further transmits the heat of the atmosphere. This process of heating the atmosphere is called convection.

Convection transfer of energy is confined only to the troposphere.

Advection

The transfer of heat through the horizontal movement of air is called Advection. The horizontal movement of air is relatively more important than the vertical movement.

In middle latitudes, most diurnal (day and night) variations in daily weather are caused by advection alone.

In tropical regions particularly in northern India during the summer season, local winds called ‘loo’ are the outcome of the advection process.

Terrestrial Radiation

The insolation received by the earth is in short waves forms and heats up its surface. The earth after being heated itself becomes a radiating body and it radiates energy to the atmosphere in the long waveform.

This energy heats up the atmosphere from below. This process is known as terrestrial radiation.

The longwave radiation is absorbed by atmospheric gases, particularly carbon dioxide and other greenhouse gases. Thus, the atmosphere is indirectly heated by the earth’s radiation.

The atmosphere in turn radiates and transmits heat to space. Finally, the amount of heat received from the sun is returned to space, thereby maintaining a constant temperature at the earth’s surface and in the atmosphere.

Heat Budget of the Planet Earth

The earth as a whole does not accumulate or lose heat. It maintains its temperature.

This can happen only if the amount of heat received in the form of insolation equals the amount lost by the earth through terrestrial radiation. Consider that the insolation received at the top of the atmosphere is 100 per cent.

While passing through the atmosphere some amount of energy is reflected, scattered, and absorbed.

Only the remaining part reaches the earth’s surface. Roughly 35 units are reflected back to space even before reaching the earth’s surface. Of these, 27 units are reflected back from the top of the clouds and 2 units from the snow and ice-covered areas of the earth.

The reflected amount of radiation is called the albedo of the earth. The remaining 65 units are absorbed, 14 units within the atmosphere and 51 units by the earth’s surface.

The earth radiates back 51 units in the form of terrestrial radiation.

Of these, 17 units are radiated to space directly and the remaining 34 units are absorbed by the atmosphere (6 units absorbed directly by the atmosphere, 9 units through convection and turbulence, and 19 units through latent heat of condensation).

48 units absorbed by the atmosphere (14 units from insolation +34 units from terrestrial radiation) are also radiated back into space.

Thus, the total radiation returning from the earth and the atmosphere respectively is 17+48=65 units which balances the total of 65 units received from the sun.

This is termed the heat budget or heat balance of the earth. This explains, why the earth neither warms up nor cools down despite the huge transfer of heat that takes place.

Variation in the Net Heat Budget at the Earth’s Surface

As explained earlier, there are variations in the amount of radiation received at the earth’s surface.

Some part of the earth has a surplus radiation balance while the other part has a deficit.

The figure shows that there is a surplus of net radiation balance between 40 degrees north and south and the regions near the poles have a deficit.

The surplus heat energy from the tropics is redistributed polewards and as a result, the tropics do not get progressively heated up due to the accumulation of excess heat, or the high latitudes get permanently frozen due to excess deficit.

FAQ

Conduction in geography?

The earth is heated by insolation and then the earth transmits the heat to the atmosphere layers in form of the long waves. The air in contact with land gets heated gradually and the upper layers in contact with the lower layers get heated too. This over process is known as Conduction.

References

• https://ncert.nic.in/ncerts/l/kegy209.pdf