Weather & Climate ABM 07013

8/8/2019 Weather & Climate ABM 07013

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WEATHER AND CLIMATE

SUBMITTED TO:

Prof M K Awasthi

DATE OF SUBMISSION: August 30, 2010

SUBMITTED BY:

Anurag Singh (ABM 07013)


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WEATHER AND CLIMATE

Weather is the state of the atmosphere as measured on a scale of hot or cold, wet or dry,

calm or storm, clear or cloudy. Most weather phenomena occur in the troposphere, just below

the stratosphere. Weather refers, generally, to day-to-day temperature and precipitation

activity, whereas climate is the term for the average atmospheric conditions over longer

periods of time. When used without qualification, "weather" is understood to be the weather

of Earth.

Weather occurs due to density (temperature and moisture) differences between one place and

another. These differences can occur due to the sun angle at any particular spot, which varies

by latitude from the tropics

Climate in a narrow sense is usually defined as the "average weather," or more rigorously, as

the statistical description in terms of the mean and variability of relevant quantities over a

period of time ranging from months to thousands or millions of years. The classical period is

30 years, as defined by the World Meteorological Organization . These quantities are most

often surface variables such as temperature, precipitation, and wind. Climate in a wider sense

is the state, including a statistical description, of the climate system.

The difference between Climate and Weather is usefully summarized by the popular

phrase "Climate is what you expect, weather is what you get."

Climate models use quantitative methods to simulate the interactions of

the atmosphere, oceans, land surface and ice. They are used for a variety of purposes from

study of the dynamics of the weather and climate system to projections of future climate. All

climate models balance, or very nearly balance, incoming energy as short wave (including

visible) electromagnetic radiation to the earth with outgoing energy as long wave (infrared)

electromagnetic radiation from the earth. Any imbalance results in a change in the average

temperature of the earth.

The most talked-about models of recent years have been those used to infer the consequences

of increasing greenhouse gases in the atmosphere, primarily carbon dioxide (see greenhouse

gas). These models predict an upward trend in the global mean surface temperature, with the

most rapid increase in temperature being projected for the higher latitudes of the Northern

Hemisphere.


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Models can range from relatively simple to quite complex:

Simple radiant heat transfer model that treats the earth as a single point and averagesoutgoing energy

This can be expanded vertically (radiative-convective models), or horizontally Finally, (coupled) atmosphereoceansea ice global climate models discretise and

solve the full equations for mass and energy transfer and radiant exchange.


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India Weather and Climate

The weather is hot most of the year with variations from region to region. The coolest

weather lasts from around December to February, with fresh mornings and evenings and

mostly sunny days. The really hot weather, when it is dry, dusty and unpleasant, is between

March and June. Monsoon rains occur in most regions in summer anywhere between June

and early October. Climatic condition at various parts in India are discussed below:

Western Himalayas: Srinagar is best from March to October; July to August can be

unpleasant; cold and damp in winter. Shimla is higher and therefore colder in winter. Places

like Gulmarg, Manali and Pahalgam are usually under several feet of snow from December to

March and temperatures in Ladakh can be extremely cold. The mountain passes of Ladakh

are accessible from July to October.

Required clothing: Light- to mediumweights are advised from March to October, with

warmer wear for winter. Weather can change rapidly in the mountains and therefore it is

important to be suitably equipped. Waterproofing is advisable.

Northern Plains: This extreme climate is typically warm inland from April to mid-June,falling to almost freezing at night in winter between November and February. Summers are

hot with monsoons between June and September.

Required clothing: Lightweights in summer with warmer clothes in winter and on cooler

evenings. Waterproofing is essential during monsoons.

Central India: Madhya Pradesh state escapes the very worst of the hot season, but monsoons

are heavy between July and September. Temperatures fall at night in winter.

Required clothing: Lightweights are worn most of the year with warmer clothes during

evenings, particularly in winter. Waterproofed clothing is advised during monsoon rains.

Western India: November to February is most comfortable, although evenings can be fairly

cold. Summers can be extremely hot with monsoon rainfall between mid June and mid

September.


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Required clothing: Lightweights are worn most of the year with warmer clothes for cooler

winters, and waterproofing is essential during the monsoon.

Southwest: The most pleasant weather is from November to March. Monsoon rains fall

anywhere between late April and July. Summer temperatures not as high as Northern India

although humidity is extreme. The coast benefits from some cooling breezes. Inland, Mysore

and Bijapur have pleasant climates with relatively low rainfall.

Required clothing: Lightweights. Waterproofing is necessary during the monsoon. Warmer

clothes are worn in the winter, particularly in the hills.

Southeast: Tamil Nadu experiences a northeast monsoon between October and December

and temperatures and humidity are high all year. The hills can be cold in winter.

Required clothing: Lightweights. Waterproofing is necessary during the monsoon. Warmer

clothes are worn in the winter, particularly in the hills.

Northeast: March to June and September to November are the driest and most pleasant

periods. The rest of the year has extremely heavy monsoon rainfall.

Required clothing: Lightweights. Waterproofing is advisable throughout the year and

essential in monsoons, usually from mid June to mid October. Warmer clothes are useful for

cooler evenings.


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Graphs Representing climatic condition at various region in India


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Seasons in India

Indian weather and climate conditions are very diverse and can reach extremes. The climate

of India is essentially a temperate one. India lies to the north of Equator, so the southern partof India is usually much warmer than the rest of India. Also, water bodies flank India on three

sides thus giving the peninsular region a maritime climate. The weather of India changes

every now and then thus giving the people the much-needed relief from the extreme weather

conditions.

Summer Season

The duration of summer in India is from March to June. It is mildly pleasant in March, a bituncomfortable in April, hot in May and scorching in June. The temperature in the plains of

northern India can go up to 45 Celsius. The southern region is equally hot. This is the time

when people pack their bags and head off to the hills and valleys where it is relatively cooler.

Monsoons

The Monsoon season in India usually lasts from the month of June to that of September.

During this time, most of the areas in the country get their share of rainfall, which leaves a

hue of greenery in its wake. The South West Monsoon enters India through the coast of

Kerala and Andaman & Nicobar Islands and passing through Mumbai, central India and

eastern India, reaches other parts of North and N West India. During the months of October

to November, some parts of South India experience rains in the form of the northeast

monsoon.

Winter Season

The winters in India can get really chilly. It becomes bone chilling during the months of

November to February. The northern part of India experiences harsh weather conditions with

cold wave sweeping almost entire northern regions and central parts of India. The hilly areas

experience sub-zero temperature conditions.


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India Agro-ecological zones

Crop yield is the function of many factors like weather, soil type and its nutrient status,

management practices and other inputs available. Of these, weather plays an important role,

probably more so in India where aberrant weather such as drought, flood, etc., is a rule rather

than an exception. Efficient crop planning, therefore, requires proper understanding of agro-

climatic conditions. This calls for collection, collation, analysis and interpretation of long-

term weather parameters available for each region to identify the length of the possible

cropping period taking into consideration the availability of water.

The agro-climatic zone planning aims at scientific management of regional resources to meet

the food, fibre, fodder and fuel wood without adversely affecting the status of natural

resources and environment. While assessing the resource base required is the holistic

perspective, development will have to be achieved through an appropriate mix of crop

production and allied activities including horticulture, forestry, animal husbandry and agro-

processing etc. improved farming systems technologies will replace traditional crop

production approach to minimize regional variations in rural incomes.

With the 329 million hectares of the geographical area the country presents a large number of

complex agro-climatic situations. However, for the purpose of this exercise, Planning

Commission has delineated 15 agro-climatic regions which were proposed to form basis for

agricultural planning for the Eighth Plan. The 15 regions are:

1. Western Himalayan Region: J&K, HP, UP, Uttaranchal

2. Eastern Himalayan Region: Assam Sikkim, West Bengal & all North-Eastern states

3. Lower Gangetic Plains Region: West Bengal

4. Middle Gangetic Plains Region: UP, Bihar

5. Upper Gangetic Plains Region: UP

6. Trans-Gangetic Plains Region: Punjab, Haryana, Delhi & Rajasthan


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7. Eastern Plateau and Hills Region: Maharashtra, UP, Orissa & West Bengal

8. Central Plateau and Hills Region: MP, Rajasthan, UP

9. Western Plateau and Hills Region: Maharashtra, MP & Rajasthan

10. Southern Plateau and Hills Region: AP, Karnataka, Tamil Nadu

11. East Coast Plains and Hills Region: Orissa, AP, TN,& Pondicherry

12. West Coast Plains and Ghats Region: TN, Kerala, Goa, Karnataka, Maharashtra

13. Gujarat Plains and Hills Region: Gujarat

14. Western Dry Region: Rajasthan

15. The Islands Region: Andaman & Nicobar, Lakshya Deep


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PHYSICAL FEATURES AND CLIMATE OF INDIA

India is the name given to the vast peninsula which the continent of Asia throws out to the

south of the magnificent mountain ranges that stretch in a sword like curve across the

southern border of Tibet. Shaped like an irregular quadrilateral, this large expanse of territory

deserves the name of a subcontinent. The name Himvat in the above passage refers not only

to the snow capped ranges of the Himalayas but also to their less elevated offshoots -the

Patkai, Lushai and Chittagong Hills in the east, and the Sulaiman and Kirthar ranges in the

west. These go down to the Sea and separate India from the wooded valley of Irrawady, on

the one hand, and the hilly tableland of Iran, on the other. The Himalayas standing tall in

breathtaking splendour are radiant in myth and mystery. These, the youngest and tallest

mountain ranges, feed the Ganga with never-ending streams of snow. The Himalayas are

home to the people of Kashmir Himachal Pradesh Uttaranchal Sikkim Arunachal Pradesh.

Mount Everest is the highest peak in the Himalayan ranges. And even as all Indian through

the ages have considered the whole of the Himalayas as their property, with Shiva himself

residing in those ranges, Mount Everest falls in Nepal's territory.

The Vindhya Mountains cut right across the country, from West to East, and form the

boundary between North and South India is also fortunate in possessing one of the worlds

most extensive and fertile lands, made up of the alluvial Soil brought down in the form of

fine silt by the mighty rivers. Lying south of the Himalayas, these Great North Indian Plains

consist of the Indus basin, Ganga-Brahmaputra basin, and the tributaries of these mighty river

systems.

To the south of the Great Plains of northern India lie the Great Plateau of Peninsular India,

which is divided into two parts, viz., the Malwa Plateau and the Deccan Plateau. The Malwa

plateau - bounded by the Aravalli hills in the northwest and the Vindhyas in the Vindhyasform the northern half of this peninsula. Chhota Nagpur region forms the northeastern part of

this plateau and is the richest minerals producing region of India. The valley of the Narmada

River forms the southern boundary of this plateau. The Deccan plateau extends from the

Satpura hills in the north to Kanniyakumari, the southernmost point in India, finally ending in

the Indian Ocean.

Towards the west of this plateau lie the Western Ghats that comprise of the Sahyadri, the

Nilgiri, the Annamalai and the Cardamom Hills. On the eastern side, this plateau merges into


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a layer of discontinuous low hills known as the Mahendra Giri hills, which comprise of the

Eastern Ghats.

Narrow coastal plains along the Arabian Sea and the Bay of Bengal flank the Deccan Plateau,

on its eastern and western sides, respectively. The Western coastal plains lie between the

Western Ghats and the Arabian Sea, further split into the northern Konkan Coast and the

southern Malabar Coast. The eastern coastal plains, on the other hand lie between the Eastern

Ghats and the Bay of Bengal and like the western plains are divided into two parts - the

Coromandel Coast as the southern part and the Northern Sircaras as the northern.

Towards the western half of India lies a vast stretch of land that is divided, by the Aravalli

mountains, into two separate units. The area west of the Aravalli comprises of the Thar

Desert - made up of sand and interrupted by rocky hills and waterless valleys, this arid land,

extend deep into Pakistan. The state of Gujarat lies to the east of this range and is one of the

most prosperous regions in India.

These mainland areas apart, India has two groups of islands - the Andaman and Nicobar in

the Bay of Bengal and the Lakshadweep in the Arabian Sea.

River System of India The Greeks applied the name 'India' to the country. It corresponds to

the "Hindu" of the old Persian epigraphs. Like "Sapta sindhavah" and "Hapta Hindu"- the

appellations of the Aryan country in the Veda and the Vedinand - it is derived from Sindhu

(Indus), the great river that constitutes the most imposing feature of that part of the sub-

continent, which seems to have been the cradle of its earliest known civilizations. Rising in

southwestern Tibet, at an altitude of 16,000 feet, Indus enters the Indian Territory near Leh in

Ladakh. The river has a total drainage area of about 4,50,000 square miles, of which 1,75,000

square miles lie in the Himalayan Mountains and foothills.

After flowing eleven miles beyond Leh, in the north Indian state of Jammu and Kashmir, the

basin is joined on the left by its first tributary, the Zanskar, which helps green the Zanskar

Valley. Many interesting mountain trails beckon the mountaineering enthusiasts to the

Zanskar Valley. The Indus then flows past Batalik. When it enters the plains, its famous five

tributaries-Jhelum, Chenab, Ravi, Beas, and Sutlej-that give Punjab (the food bowl of India)

its name as the "land of five rivers," join it.


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However, much of the myth and sentiment attached to India is related with the Ganges. The

gushing waters of the Ganges are at once peaceful, and at once tumultuous. Nature's glory

and man's aspirations have long met along the Ganges. As her civilization spread out further,

a pilgrimage had to be undertaken to reach her watery shores. Fairs and festivals began to be

celebrated on her banks. The history of Ganga is as long as the history of Indian civilization.

Barring the period of Harappan civilization, Ganga basin has been the spectator to all the

actions that shaped mythology, history, and people of India. It was in this plain that the great

kingdoms of India, viz., Magadh, Gupta, and Mughals found their home. It was in this region

that one of the most homogenous cultures of all times was born. Furthermore, it was in this

place that the essence of Hinduism, Buddhism, Jainism, and Sikhism was established in

India. Ever since then, the river has been the lifeline of India, economically, spiritually and

even culturally.

The mighty Ganga (also Ganges) emerges from beneath the Gangotri glacier at a height of

3,959 m above sea level, in the Garhwal region of North India. Here she is known as the

Bhagirathi, after the legendary prince Bhagirath who is accredited with bringing her down

from heaven to earth. Bursting forth at Gaumukh, out of a huge cavern shaped like the mouth

of a cow, snow laden and hung with giant icicles, the Bhagirathi goes rushing, sparkling,

foaming around chunks of ice that are constantly breaking off from the glacier above.

Eighteen kilometers downstream, stands Gangotri, which was the source of the river until the

glacier melted and retreated to its present position above Gaumukh. From here, onwards the

river passes through the plains of North India, covering the states of Uttar Pradesh, Bihar,

West Bengal, and Bangladesh. From Haridwar to Allahabad, the Ganga flows parallel to the

Yamuna, another important river flowing through North India and also a major tributary of

the Ganges, each describing a huge arc. Along the route that Ganga and her tributaries took,

they set up different settlements, each of which was distinct and developed its own

indigenous culture. Like the Ganges, the vast networks of rivers flowing throughout India are

sacred to its people. The region south of the Gangetic Plains in north India is a highland zone

rising to the chain of the Vindhya Mountains - forming the land of the river Cauvery. Long

revered by the people of India, for the bounties of fertility bestowed by the gentle waters, this

river flows from the azure mountains of the Nilgiris. Today, this region covering the four

south Indian states of Tamil Nadu, Kanataka, Kerala and Andhra Pradesh offers visible

continuity with traditions in time. Above the land of Cauvery lies Orissa, another culturally

rich state in India that is fed by the river Mahanadi.


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Through the east of India, flows the very cascading Brahamputra. The waters of the

Brahmaputra travel all the way from China to the plains of the Indian state of Assam. Further

northeast are seven other states of Tripura, Meghalaya, Manipur, Arunachal Pradesh,

Nagaland , Mizoram,and Sikkim - together known as the seven sisters. The two rivers of

Narmada and Tapti in central and western India have a unique distinction of flowing in the

east to west direction, unlike other major rivers in India. Out of the two, Narmada has more

mythological significance as being the mother and giver of peace. Legends in India have it

that the mere sight of this river is enough to cleanse one's soul, as against a dip in the Ganga

or seven in the Yamuna.

Climate, soil and flora and fauna

The Himalayan range in the north acts as the perfect meteorological barrier for the whole

country. Despite the country's size and its varied relief, the seasonal rhythm of the monsoon

is apparent throughout. Although much of northern India lies beyond the tropical zone, the

entire country has a tropical climate marked by relatively high temperatures and dry winters.

Yet India is blessed with a wide variety of climates due to the varied topography and many

soil types, which permit the growing of many unique earthy roots, precious woods, aromatic

spices, exotic flowers, balsamic resins and scented grasses. Practitioners of Ayurveda (the

traditional Indian system of medicine dating to at least 1000 BC) were well acquainted with

the uses to which these plants could be put and prescribed them to treat the emotional, mental

and physical ailments of the people. Sandalwood, agarwood, spikenard, vetiver, saffron,

cinnamon, jasmine, rose, coriander and ginger were but a few of the aromatic plants

recognized by them as being plants possessing pleasing fragrant charm as well as being plants

therapeutic value. These plants and many others were used in food preparations, medicinal

formulas, massage oils, cosmetics, natural sandalwood-based perfumes called attars, incense,

floral wreaths and unguents, each of which served some special function in promoting the

well-being of the people.


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Cropping Seasons

India has three cropping seasons in India: RABI, KHARIF and ZAID.

Rabi: Rabi crops are grown in sown in winter from October to December and harvested in

summers from April to June. Some of the important Rabi crops in India are wheat, barley

gram, mustard and peas. Though these crops are grown in large parts of India, states from the

north and North West like Punjab, Haryana, Himachal Pradesh, Jammu & Kashmir,

Uttaranchal, & UP are important for the production of wheat and Rabi crops. Avaliability of

precipitation during winter months due to western temperate cyclones help in the success of

these crops.

Kharif : Kharif crops are grown on the onset of monsoon in different parts of country and

harvested in SeptemberOctober. Important crops grown during this season are paddy,

maize, jowar, bajra, tur(arhar), moong, urad, cotton, jute groundnut and soyabean. Some of

the important rice growing regions are Assam, West Bengal, coastal region of Orissa, Andhra

Pradesh, Tamil Naidu, Kerala and Maharashtra.

Zaid: In between Rabi & Kharif season, there is a short season during the summer months

known as the Zaid Season. Some of the crops during Zaid are watermelon, muskmelon,

cucumber, vegetables and fodder crops, Sugar cane takes almost a year to grow.

Cropping Patterns

Cropping activities go on all the year-round in India, provided water is available for crops. In north

India, there are two distinct seasons, kharif(July to October), and rabi (October to March). Crops

grown between March and June are known aszaid. In some parts of the country, there are no such

distinct seasons, but there they have their own classification of seasons. The village revenue officials

keep plot-wise record of crops grown in each season. These are annually compiled district-wise,

statewise and on all-India basis. From these records one could calculate the relative abundance of a

crop or a group of crops in a region. These crops are grown sole or mixed (mixed-cropping), or in a

definite sequence (rotational cropping). The land may be occupied by one crop during one season

(mono-cropping), or by two crops (double-cropping) which may be grown in a year in sequence.

Of late the trend is even more than two crops (multiple-cropping) in a year.These intensive croppin

may be done either in sequence or even there may be relay-cropping-one crop under sown in a


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standing crop. With wide-rowed slow growing cropping patterns, companion crops may be grown.

There are various ways of utilising the land intensively. It is proposed to give a synoptic view of

cropping patterns prevalent in the country. Before dealing with the cropping patterns, a brief

description of the factors that determine the cropping systems of an individual locality or region arebriefly presented here.

In any locality, the prevalent cropping systems are the cumulative results of past and present decision

by individuals, communities or governments and their agencies. These decisions are usually based on

experience, tradition, expected profit, personal preferences and resources,social and political pressure

and so on. Essentially, they are answers to some of the following questions:

What with the present pest-and-disease control methods are ecologically practicable? What interactions occur among the ecologically practicable crop, and the chosen crops and

must be combined in a special way (rotations) in the farming systems?

Are any of the ecologically feasible crops ruled out by infrastructural factors? Which of the crops, now remaining on the list, are most profitable (or yield most food in a

subsistence agriculture)?. In what combinations and at what level of input application would

they make the best use of local land, climate and input resources in short-term and long-term

situations bearing in mind the degree of food and income security required by the individualfarmer and the community?

What operational factors rule out or amend the size and the method of any of theeconomically preferable crop combinations thereof?

Finally, are the crop combinations, the farming systems and the input levels suggested by thisprocess of the individual farmers compatible with his own skills, enterprise preferences,

health, age and capital?

The climatic and socio-economic diversity of the Indian crop-production scene is dotted with many

cropping patterns. With a geographic area of 328.048 million hectares, stretching between 8oN and

36oN latitude and between 68

oE and 98

oE longitude, its altitude varying from the mean sea-level to

the highest mountain ranges of the world, India presents a range and diversity of climate, flora and

fauna, with a few parallels in the world. The country presents a paradox of containing in it the station

with the highest mean annual rainfall in the world (Cherrapunji in Assam) and also dry, semi-desert

area in Rajasthan. The variability of rainfall is most important in all the states, but especially where

rainfall is low. In parts of Rajasthan and the Deccan, the variability is more than 100 per cent of the


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mean. Years of drought account for only too frequent a history of crop failures, whereas the years of

flood also cause very considerable loss of agricultural production. Temperatures also vary greatly,

both geographically and seasonally. Northern and central parts of India in January have temperature

comparable with those in Europe in July, though with a greater daily range, but in these places in thepre-monsoon months the maximum temperatures of over 40

oC are reached over a large area. Frost

may occur in winter in the plains, as far south as a line drawn through Madhya Pradesh and may be

heavy in Kashmir and areas north of Punjab.

Socio-economically, the peasantry ranges from the relatively affluent Punjabi farmers who operate

with a high input intensity in agriculture to the subsistent farmers of eastern and central India. They

even today, sometimes practice shifting cultivation. Between these two extremes, various intensities

cultivation are practised. The outstanding fact on the socio-economic is the smallness of holdings,

the average farm-size in most areas being lower than that is in most tropical countries.

Crops production, therefore, presents such an enormous diversity owing to differences in latitude,

altitude and variability of rainfall and edaphic diversity which have presented in detail in the book.

Thus it may not be possible to enumerate and describe here every type of cropping pattern prevalent

the country. Some broad contours of farming, however, emerge. The most important element of

farming in India is the production of grains and the dominant food-chain is grain-man. On this basis,the country may be divided broadly into five agricultural regions.

The rice region extending from the eastern part to include a very large part of the north-easterand the south-eastern India, with another strip along the western coast.

The wheat region, occupying most of the northern, western and central India. The millet-sorghum region, comprising Rajasthan, Madhya Pradesh and the Deccan Plateau

the centre of the Indian Peninsula.

The temperate Himalayan region of Kashmir, Himachal Pradesh and Uttar Pradesh and someadjoining areas. Here potatoes are as important as cereal crops (which are mainly maize and

rice), and the tree-fruits form a large part of agricultural production.

The plantation crops region of Assam and the hills of southern India where good quality tea iproduced. There is an important production of high-quality coffee in the hills of the western

peninsular India. Rubber is mostly grown in Kerala and parts of Karnataka and Tamil Nadu.

There are some large estates, but most of the growers would come under the category of smal

holders. Sugarcane, which in many countries is a plantation crop, is almost entirely grown by


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small holders in India.

There had been substantial investments in major irrigation works in the colonial days. The post-

Independence era saw many multi-purpose irrigation works. Lately, interest in the medium and mino

irrigation works has increased, especially after the drought of 1966. Thus, at present, an all-India

irrigation potential of 38.5m ha has been created and is expected to increase up 110 m ha by 2025.

Irrigation, especially the minor works, has provided a base for multiple-cropping. The All-India Co-

ordinated Crops-Improvement Projects run co-operatively by the Indian Council of Agricultural

Research and the agricultural universities have generated short-season, photo-period-insensitive high

yielding varieties of various crops suitable for a high intensity of cropping. The adaptability of these

varieties on the farmer's fields has been demonstrated in the National Demonstration Programme

spread all over the country. The various developmental and the educative programmes, especially the

High Yielding Varieties Programme, have also resulted in newer cropping patterns involving

intensive cropping. The area of rice has increased in Punjab and Haryana. Similarly wheat is now

grown in West Bengal and to some extent in the southern states of the country.

All these factors have led to the present cropping patterns, which are getting more and more intensive

both in respect of the number of crops grown per year and in respect of the intensity of inputs utilized

in the production of these crops.


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The annual distribution of rainfall in India is uneven. The highest annual rainfall, that is

around 1141.9 cm in the world, has been recorded at. On the other hand, the western part of

Rajasthan is one of the driest parts of the country recording around 9 cm of rainfall in a year.

Thus, it is evident that there is a wide contrast in the amount of rainfall received by different

parts of India. Total rainfall increases generally eastwards and with height. Increase in

precipitation is high at an elevation of around 1,500 metres in the. The monsoon depressions

cause widespread rainfall in the north-eastern part of the Indian Peninsular Plateau and the

Ganga Plain. It is due to these depressions that rainfall is evenly distributed in the north-

eastern part of the country.

In India, the temperature is high enough to promote the growth of crops at most of the places

throughout the year. However, it is the availability of water that determines to a great extent

the success of crops, zones of vegetation and crop patterns. In this country, around 75 per

cent of the total area sown is with rainfall. Thus, the total yearly rainfall as well the number

of rainy months of an area is very significant in the country. A rainy month is the one that

receives more than one-twelfth of the mean annual rainfall. On the basis of total annual

rainfall in the country, it is divided into five major regions. These five regions of the country

are as follows :

Areas of Inadequate Rainfall (it implies rainfall less than 50 cm a year) - there are basically

two belts that receive inadequate rainfall. These belts are of small extent and some parts of

these belts receive exceptionally very low rainfall. Like for instance, the Karakoram

Mountains and area lying to the north of the . This region is situated in the north of the

Himalayas. It, therefore, receives little rainfall during the summer monsoon rainy season.

Further, a little rainfall is also caused in the months of January, February and March by the

westerly depressions. Thus, it is evident that there are two maxima of rainfall in this region.

Rainfall in late spring increases westward and August receives maximum rainfall. The rainy

months are July and August and exceptionally January, February and March. This region is

however very dry and nothing grows without irrigation.

The other region of India that receives extremely low rainfall is the western part of

Rajasthan. These portions are lying to the west of a line starting from Kutch Coast and

running northwards through the delta of the Haryana near Hissar. Moreover, it also comprisessmall patch of Punjab, Andhra Pradesh, Maharashtra, Karnataka and Ladakh.


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Besides, the narrow belt of mountainous country running in northwest-southeast direction. It

comprises mainly the Zanskar range. Basically there are two maxima of rainfall, one in

August and the other one in either March or April and the six rainy months are July and

August and January to April. November is the driest month and it receives around 2.5 cm of

rainfall.

Secondly, crescent shaped belt of around 150 to 300 km of width running through north-

south direction. It comprises Punjab-Haryana plain west of a line starting roughly from

Amritsar, central belt of Rajasthan and the western Gujarat excluding the more arid western

Kutch. This belt mainly has four rainy months (June to September) and other months are

basically dry.

The third distinctive zone is a narrow belt of around 100 km width, running in the north-south

direction. It is lying east of the Western Ghats. It also runs through the western part of the

Maharashtra Plateau, extending further southward in Karnataka and south-east Andhra

Pradesh. The belt runs southwards from the Satpura Range. The southern limit of the belt has

five rainy months (June to October). July is the rainiest month in the northern belt and

September is the rainiest month in the southern belt. Further, south the number of rainy

months increases from five to six (May and June and August to November).

Areas of Low Rainfall (it implies rainfall around 50 to100 cm a year) - it is a long belt

running from towards southward. It is interrupted by a narrow belt of low rainfall of the

Western Ghats and also by a few patches of low rainfall in the interior of Tamil Nadu. In this

long belt almost crossing the country from north to south, the time of the onset of the rainy

season and the number of the rainy months vary from one part of the region to another.

Medium Rainfall Zone (it implies rainfall in between 100 to 200 cm a year) - the different

areas of high rainfall in India and these are widely separated from one another. Firstly, a

narrow belt in the Western Ghats running throughout their length in the north-south direction.

The number of rainy months increases towards the south. Like there are four rainy months

(June to September) in the north and five rainy months (June to October) in its middle part.

Himachal Pradesh, Uttar Pradesh, West Bengal, Orissa and few districts of Maharashtra form

the largest single block of high rainfall in India. Tripura is also an area of high rainfall.

High Rainfall Zone (it implies rainfall above 200 cm a year) - there are mainly two areas of

very high rainfall. Firstly, a long belt running southwards. In the northern part of this belt,


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there are four rainy months (June to September). July is the rainiest month. Darjeeling

District of West Bengal and some states of north eastern India form the other belt of the very

high rainfall zone. In this zone, there are some areas of exceptionally high rainfall. Arunachal

Pradesh is also an area of very high rainfall. January and December are dry months receiving

less than 3 cm rainfall. Thus, it can be said that in India the distribution of annual rainfall is

uneven with several rainfall zones.

Rainfall variability

The Indian summer monsoon rainfall is known to have considerable spatial variability, which

imposes some limitations on the all-India mean widely used at present. To prepare a spatially

coherent monsoon rainfall series for the largest possible area, fourteen subdivisions covering

the north western and central parts of India (about 55% of the total area of the country),

having similar rainfall characteristics and associations with regional/global circulation

parameters are merged and their area-weighted means computed, to form monthly and

seasonal Homogeneous Indian Monsoon (HIM) rainfall series for the period 18711990. This

paper includes a listing of monthly and seasonal rainfall of HIM region. HIM rainfall series

has been statistically analysed to understand its characteristics, variability and tele-

connections for long-range prediction.

Weather Forecasting

Weather forecasting is the application of science and technology to predict the state of

the atmosphere for a future time and a given location. Human beings have attempted to

predict the weather informally for millennia, and formally since at least the nineteenth

century. Weather forecasts are made by collecting quantitative data about the current state of

the atmosphere and using scientific understanding of atmospheric processes to project how

the atmosphere will evolve.

Once an all-human endeavour based mainly upon changes in barometric pressure, current

weather conditions, and sky condition, forecast models are now used to determine future

conditions. Human input is still required to pick the best possible forecast model to base the

forecast upon, which involves pattern recognition skills, teleconnections, knowledge of

model performance, and knowledge of model biases. The chaotic nature of the atmosphere,

the massive computational power required to solve the equations that describe the

atmosphere, error involved in measuring the initial conditions, and an incomplete


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understanding of atmospheric processes mean that forecasts become less accurate as the

difference in current time and the time for which the forecast is being made (the range of the

forecast) increases. The use of ensembles and model consensus help narrow the error and

pick the most likely outcome.

There are a variety of end users to weather forecasts. Weather warnings are important

forecasts because they are used to protect life and property. Forecasts based

on temperature and precipitation are important to agriculture, and therefore to traders within

commodity markets. Temperature forecasts are used by utility companies to estimate demand

over coming days. On an everyday basis, people use weather forecasts to determine what to

wear on a given day. Since outdoor activities are severely curtailed by heavy rain, snow and

the wind chill, forecasts can be used to plan activities around these events, and to plan ahead

and survive them.

How Models create forecast

Data collection

Surface weather observations of atmospheric pressure, temperature, wind speed and

direction, humidity, precipitation are made near the Earth's surface by trained

observers, automatic weather stations or buoys. The World Meteorological Organization acts

to standardize the instrumentation, observing practices and timing of these observations

worldwide. Stations either report hourly in METAR reports, or every six hours in SYNOP

reports.

Measurements of temperature, humidity and wind above the surface are found by

launching radiosondes on weather balloons. Data are usually obtained from near the surface

to the middle of the stratosphere, about 21 km (13 mi).In recent years, data transmitted from

commercial airplanes through the Aircraft Meteorological Data Relay (AMDAR) system has

also been incorporated into upper air observation, primarily in numerical models.

Increasingly, data from weather satellites are being used because of their almost global

coverage. Although their visible light images are very useful for forecasters to see

development of clouds, little of this information can be used by numerical weather prediction

models. The infrared (IR) data however can be used as it gives information on the

temperature at the surface and cloud tops. Individual clouds can also be tracked from onetime to the next to provide information on wind direction and strength at the clouds steering


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level. Both polar orbiting and geostationary satellites provide soundings of temperature and

moisture throughout the depth of the atmosphere. Compared with similar data from

radiosondes, the satellite data has the advantage of global coverage, however at a lower

accuracy and resolution.

Meteorological radar provide information on precipitation location and intensity, which can

be used to estimate precipitation accumulations over time. Additionally, if a Pulse

Doppler weather radar is used then wind speed and direction can be determined.

Modern weather predictions aid in timely evacuations and potentially save lives and property

damage

Data assimilation and analysis

During the data assimilation process, information gained from the observations is used in

conjunction with a numerical model's most recent forecast for the time that observations were

made, since this contains information from previous observations. This is used to produce a

three-dimensional representation of the temperature, moisture and wind called a

meteorological analysis. This is the model's estimate of the current state of the atmosphere.

Numerical weather prediction

Numerical weather prediction models are computer simulations of the atmosphere. They take

the analysis as the starting point and evolve the state of the atmosphere forward in time

using physics and fluid dynamics. The complicated equations which govern how the state of

a fluid changes with time require supercomputers to solve them. The output from the model

provides the basis of the weather forecast.

Model output post processing

The raw output is often modified before being presented as the forecast. This can be in the

form of statistical techniques to remove known biases in the model, or of adjustment to take

into account consensus among other numerical weather forecasts.MOS or model output

statistics is a technique used to interpret numerical model output and produce site-specific

guidance. This guidance is presented in coded numerical form, and can be obtained for nearly

all National Weather Service reporting stations in the United States.


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Climatic Changes in India

Climate is the average pattern of weather for a particular region over a long period of time.

Climate Change refers to a significant variation in either the mean state of the climate or in its

variability, persisting for an extended period, typically, decades or longer. Burning of coal,

oil, and natural gas , deforestation, various agricultural and industrial practices are altering

the composition of the atmosphere and contributing to it. These human activities have led to

increased atmospheric concentration of a number of greenhouse gases, including carbon

dioxide, methane, nitrous oxide, chlorofluorocarbons, and troposphere ozone in the lower

part of the atmosphere. India is highly vulnerable to climate change as its economy depends

mainly on the climate-sensitive sectors like agriculture and forestry. Its low-lying densely

populated coastal areas are threatened by a potential rise in sea level.

In developing countries like India, climate change could spell an additional stress on

ecological and socio-economic systems which are already facing tremendous pressures due to

rapid urbanization, industrialization and economic development.

A recent study done by me and my group members of Einstein Club, Rewari on various

climate change and bio-diversity issues shows concern of the local population.

82% of population think that climate change, less rainfall, long dry spell are a bigthreat.

They opine that Government should bring out some legislation or measures tocurb the excessive use of natural resources and materials responsible for adverse

effect on climate.

People and Organizations helping in protecting environment should be properlyrewarded.

Changes in India's annual monsoon are expected to result in severe droughts and intense

flooding in many parts. Alterations in water resources may affect human health, agriculture,

forests and wildlife.

62% population believes that industries, SEZ, malls, housing societies etc. aredisturbing natural habitat and eco-system.


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71% population believes that Govt. and NGOs should take initiative to protectclimate of the region.

Save Bio-Diversity and climate change project in the area is not heard by anyone sofar.

71% of population believes in life style and attitude of consuming more and moreof natural resources .

Climate change studies undertaken reveal that everyone in community should be informed

about climate change and action should be taken to prevent long term damage to India's water

cycle. This is essential since livelihood of a vast population in India depends on agriculture,

forestry, wetlands and fisheries and land use in these areas is strongly influenced by water-

based ecosystems that depend on monsoon rains. Changes to the water cycle may also cause

an increase in water borne diseases. Agriculture and allied activities constitute the single

largest component of Indias economy, contributing nearly 27% of the GDP. However, given

that 62% of the cropped area is still dependent on rainfall; climatic changes that affect rainfall

pattern could have a profound impact on production and fertility.

Forests make a considerable contribution to the Indian economy. Forests contribute 1.7% tothe GDP of the country and non-timber forest products provide about 40% of total forest

revenues and 55% of forest-based employment. Nearly 55 million people living in and

around forests in India depend upon non-timber forest products as a critical component for

their sustenance. Hence common man should be communicated about how to protect and

sustain environment to check climate change.

The best ways to communicate about climate change to masses at local and global level is by

giving-:

High priority and high interest by media High focus and long term vision of government agencies in protecting and promoting

green technologies

Improving common man and science community communication Strong political will to support clean environment issues


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Translation and communication of these issues through multimedia in all regionallanguages in India.

Highlighting good practices, glorifying achievements of people/ institutions inpreserving climate on earth.

We should take immediate steps to slow down climate change for fast Socio- Economic

development of the people on sustainable basis

We must ensure that whatever we do, as populations expand and lifestyles change, theworld must be kept in good condition in order to make available the same natural

resources that we have to the coming generations. Natural resources that include:

fresh air, clean water, farmland, wildlife, forests, unpolluted seas and a stable climate.

Roads, factories and housing should not destroy habitats of animals and plants.Bio-fuel development supported by new technologies need to be accelerated, aided by

policies that provide direct incentives to invest in the most efficient bio-fuels. If we dont act

now, we will leave a much larger problem to future generations. The good news is that, if we

all join in to stop climate change, we can reduce its impact on our planet earth.

CLIMATE CHANGE & AGRICULTURE IN INDIA

India is a large country with 15 agro-climatic zones, with diverse seasons, crops and farming

systems. For a majority of people in India, to this day, agriculture is the main source of

livelihood. Agriculture is the most vulnerable sector to CC as it is inherently sensitive to

climate variability and CC will leave its impacts on Indian agriculture in various direct and

indirect ways. This obviously means an impact on the lives and livelihoods of millions of

Indians.

For instance, it is reported that about two-thirds of the sown area in the country is drought-

prone and around 40 million hectares is flood-prone. The poorest people are likely to be

hardest hit by the impacts of climate variability and change because they rely heavily on

climate-sensitive sectors such as rain fed agriculture and fisheries. They also tend to be

located geographically in more exposed or marginal areas, such as flood plains or nutrient-

poor soils. The poor also are less able to respond due to limited human, institutional and

financial capacity and have very limited ability to cope with climate impacts and to adapt to achanging hazard burden.


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Impacts of Climate Change on agriculture: Climate change is manifesting itself in many

ways across the country. Among the indicators, while long term rainfall data analysis shows

no clear trend of change, regional variations as well as increased rainfall during summer and

reduced number of rainy days can be noticed. In the case of temperature, there is a 0.6oC rise

in the last 100 years and it is projected to rise by 3.5-5o

C by 2100. The carbon dioxide

concentration is increasing by 1.9 ppm each year and is expected to reach 550 ppm by 2050

and 700 ppm by 2100. Extreme events like frequency of heat and cold waves, droughts and

floods have been observed in the last decade. The sea level has risen by 2.5mm every year

since 1950 while the Himalayan glaciers are retreating. These are all symptomatic of climate

change.

Available research indicates that climate change-induced rise in temperature is going to affect

rainfall patternsfarming in India depends on monsoons and there is a close link between

climate and water resources.

The organic carbon levels and moisture in the soil will go down while the incidence of runoff

erosion will increase. The quality of the crop will also undergo change with lower levels of

nitrogen and protein and an increased level of amylase content. In paddy, zinc and iron

content will go down which will impact reproductive health of animals. Insect lifecycles will

increase which in turn will raise the incidence of pest attacks and virulence. Other likely

impacts are change in farm ecology viz. bird-insect relations, and an increase in the sea levels

which will cause salinity ingression and submergence.

It is projected that due to climate change, kharif rainfall is going to increase and this might be

positive for kharif crops. Further, for kharifcrops, a one-degree rise in temperature may not

have big implications for productivity. However, temperature rise in rabi season will impact

production of wheat, a critical food-grain crop.

The surface air temperatures will increase by 2 to 4C by 2070-2100. As mentioned earlier,

the rabi crop will be impacted seriously and every 1oC increase in temperature reduces wheat

production by 4-5 million tons, as per a study by IARI. This loss can be reduced to 1-2

million tons only if farmers change to timely planting. Increased climatic extremes like

droughts and floods are likely to increase production variability. Productivity of most cereals

would decrease due to increase in temperature and decrease in water availability, especially

in Indo-Gangetic plains. The loss in crop production is projected at 10-40% by 2100,depending upon the modeling technique applied.


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The impacts of climate change are already visible. A network of 15 centers of ICAR working

on studying climate change has reported that apple production is declining in Himachal

Pradesh due to inadequate chilling. This is also causing a shift in the growing zone to higher

elevations. Similarly, in the case of marine fisheries, it has been observed that Sardines are

shifting from the Arabian Sea to the Bay of Bengal, which is not their normal habitat. In fact,

fisheries are the most vulnerable sector to climate change. Crops have the ability to adapt to

extreme climate variability even up to, say, 40C while fishes and animals do not. It has also

been recorded that the pest ecology of certain crops is changing due to climate change.

Extreme weather conditions resulting in disasters will obviously have their own socio-

economic impacts, especially on the poor. Further, changes in crop productivity will have

implications on farmers incomes.

Impacts of agriculture on Climate Change: While climate change affects Indian farming

and farmers livelihoods adversely, the converse is also true Indian agriculture, even if not

in the same degree as the developed worlds agriculture, does contribute to Climate Change.

Capital depletion and massive additions of external inputs in a linear model (as opposed to

cyclical systems in ecological farming models) are characteristic features of intensive,

industrialized models of agriculture. In this model, a farm is treated like a factory with inputs

and outputs calculated in a mono cropped situation with grain yield given the highest

importance compared to any other parameter and often, the externalized costs are ignored.

Amongst various GHGs that contribute to global warming, carbon dioxide is released through

agriculture by way of burning of fossil fuel; methane is emitted through agricultural practices

like inundated paddy fields, for example; nitrous oxide through fertilizers, combustion of

fossil fuels etc. Nitrous oxide has a global warming potential 296 times greater than CO2. In

India, it is estimated that 28% of the GHG emissions are from agriculture; about 78% of

methane and nitrous oxide emissions are also estimated to be from agriculture.

As per the Intergovernmental Panel on Climate Change (IPCC), every quintal of nitrogen

applied in farming emits 1.25 kg of nitrous oxide and globally half of the nitrogen applied to

crops is lost to the environment. The greenhouse gas (GHG) emissions from fertilizer

manufacture and use in India reached nearly 50 million tones of CO2-equivalent in 2006/07,which represents about 3 percent of total Indian greenhouse gas emissions.


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Another major contributor of GHGs is the burning of crop residues. In Punjab, wheat crop

residue from 5,500 square kilometers and paddy crop residues from 12,685 square kilometers

are burnt each year. Every 4 tons of rice or wheat grain produces about 6 tons of straw.

Emission Factors for wheat residue burning are estimated as: CO- 34.66g/Kg, NOx

2.63g/Kg, CH40.41g/Km , PM103.99g/Kg, PM2.53.76g/Kg.

Burning of crop residues also impacts the soil (fertility). Heat from burning straw penetrates

into the soil up to 1 cm, elevating the temperature as high as 33.842.2C. Bacterial and

fungal populations are decreased immediately and substantially in the top 2.5 cm of the soil

upon burning. Repeated burning in the field permanently diminishes the bacterial population

by more than 50%. The economic loss due to the burning of crop residues is colossal. Each

year 19.6 million tonnes of straw of rice and wheat, worth crores of rupees are burnt. Used as

recycled biomass, this potentially translates into 38.5 lakh tonnes of organic carbon, 59,000

tonnes of nitrogen, 2,000 tonnes of phosphorous and 34,000 tonnes of potassium every year.

Another potent GHG is methane which is emitted in copious amounts through inundated

paddy cultivation. In India, of a total area of 99.5 Mha under cereal cultivation, 42.3 Mha (or

42.5%) is under rice cultivation. It is grown under flooded conditions and the seedbed

preparation involves plowing when the soil is wet to destroy aggregates and reduce the

infiltration rate of water. Such anaerobic conditions lead to emission of methane and possibly

nitrous oxide through inefficient fertilizer use. Emission of methane from rice paddies in

India is estimated at 2.4 to 6 Teragram (Tg) out of the world total emission of 25.4 to 54 Tg

from all sources and 16 to 34 Tg from rice cultivation. The average methane flux from rice

paddies ranges from 9 to 46 g/m2 over a 120- to 150-day growing season.

Another indirect contribution of agriculture to GHG emissions comes in the form of large

dams. Large dams contribute 18.7% of emissions in India as per an estimate. Total methane

emissions from India's large dams could be 33.5 million tonnes (MT) per annum, including

emissions from reservoirs (1.1 MT), spillways (13.2 MT) and turbines of hydropower dams

(19.2 MT).

The livestock sector is another major contributor to production of GHGs. For the year 1997,

livestock contributed 9.0 Tg methane and 1 Gg nitrous oxide which in terms of CO

equivalent it is around 190 Tg. Shift to stall-fed systems of livestock rearing creates problems

with the dung while shift from fodder to feed, concentrates etc. carries higher ecological foot


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prints. There is also the issue of more energy use in intensive farming models in the form of

fossil fuels for machinery like tractors, harvesters and so on, pumps for irrigation etc.

INDIAS NATIONAL ACTION PLAN ON CLIMATE CHANGE (NAPCC)

India has announced a National Action Plan on Climate Change in August 2008. The

NAPCCs formulation processes were found to be very top-down and non-participatory by

many analysts.

The NAPCC proposes to address climate change-related issues in India through the setting up

of eight inter-connected Missions: National Solar Mission; National Mission for Enhanced

Energy Efficiency; National Mission on Sustainable Habitat; National Water Mission;

National Mission for Sustaining the Himalayan Ecosystem; National Mission for a Green

India; National Mission for Sustainable Agriculture and National Mission on Strategic

Knowledge for Climate Change.

Documents

Weather & Climate ABM 07013