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The Sun is the primary source of heat to the Earth and its atmosphere. The heat received from other celestial bodies as well as the interior of the Earth is rather too significant. The distance that separates the Earth from the Sun is about 149.0 million km. The diameter of the Sun measures roughly about 1.3824 million km. The surface temperature of the Sun is estimated between 5500^o C and 6100^o C. (or 5762^o K).

The weight of the sun is about 1.9 X 10 30kg. The radius is 6.97 X 10 8 m or the diameter of the sun is 14 X 10 5 km. The mass of the earth is 6 X 10 24 kg, the radius is 6.4 X 10 6 m. The gravitational force of the earth is 9.81m/s². Whereas the sun‘s attractive force is 274m/s². This is 25 times higher than earth’s gravitational force.

The process through which heat energy is transferred from a body at higher temperature to a body at lower temperature without any material medium between the two bodies is x called radiation. The outer surface of the the Sun is at higher temperature compared to the surface of the earth. Solar radiation is the electromagnetic energy emitted by the Sun. It is the primary source of energy for the Earth’s climate system, driving atmospheric and oceanic circulation, influencing weather patterns, and sustaining life through photosynthesis.2 This energy  travelsthrough space as electromagnetic waves, encompassing a broad spectrum of wavelengths, from high-energy gamma rays and X-rays to ultraviolet, visible, infrared, and radio waves. The portion of this spectrum that reaches the Earth’s surface is crucial for a multitude of processes, making the study of solar radiation fundamental to understanding our planet’s environment. This introduction will lay the groundwork for exploring the characteristics, distribution, and interaction of solar radiation with the Earth’s atmosphere and surface.
4.1. Wave Length of Radiation
The wavelength of radiation refers to the distance between two consecutive peaks or troughs of a wave. It’s a measure of the length of one complete cycle of the wave (Fig. 4.1).

Sun is the prime source of energy injected into the earth’s atmosphere. The sun is the nearest star to the earth. It is a hot ball of glowing gases at the heart of the solar system. Its radiant energy is practically the only energy source to the earth. Very small and insignificant quantities of energy are available from other sources such as the interior of the earth, the moon, and other stars. Without the sun’s intense energy and heat, there would be no life on earth.

NATURE AND PROPERTIES OF SOLAR RADIATION

The mean distance of the sun from the earth, also known as one astronomical unit (1 AU), is approximately 1.496 × 10⁸ km, though the distance varies as the earth revolves round the sun in an elliptical orbit. At this average distance, light travels from the sun to earth in about 8 minutes and 19 seconds. The energy of the sunlight supports almost all life on earth by photosynthesis, and drives earth’s climate and weather. The minimum sun-earth distance is about 0.983 AU and the maximum is approximately 1.017 AU. The earth is at its closest point to the sun (perihelion) on around January 3 and at its farthest point (aphelion) on around July 4.

Sun is the prime source of energy injected into the earth’s atmosphere. The sun is the nearest star to the earth. It is a hot ball of glowing gases at the heart of the solar system. Its radiant energy is practically the only energy source to the earth. Very small and insignificant quantities of energy are available from other sources such as the interior of the earth, the moon, and other stars. Without the sun’s intense energy and heat, there would be no life on earth.

The mean distance of the sun from the earth, also known as one astronomical unit (1 AU), is approximately 1.496 × 10⁸ km, though the distance varies as the earth revolves round the sun in an elliptical orbit. At this average distance, light travels from the sun to earth in about 8 minutes and 19 seconds. The energy of the sunlight supports almost all life on earth by photosynthesis, and drives earth’s climate and weather. The minimum sun-earth distance is about 0.983 AU and the maximum is approximately 1.017 AU. The earth is at its closest point to the sun (perihelion) on around January 3 and at its farthest point (aphelion) on around July 4.

The sun makes up about 99.86% of the mass of the entire solar system. The visible disk or photosphere has a radius of 6.599 × 10⁵ km, and the solar mass is 1.989 × 10³⁰ kg. The sun is a completely gaseous body. The chemical composition (by mass) of the outer layers of sun is 71 per cent hydrogen, 26.5 per cent helium, and 2.5 per cent heavier elements like oxygen, carbon, neon, and iron among others. Since the sun is not a solid body, different parts of the sun rotate at different rates. At the equator, the sun spins once about every 25 earth days, but at its poles the sun rotates once on its axis every 36 days.

The process through which heat energy is transferred from a body at higher temperature to a body at lower temperature without any material medium between the two bodies is x called radiation. The outer surface of the the Sun is at higher temperature compared to the surface of the earth. Solar radiation is the electromagnetic energy emitted by the Sun. It is the primary source of energy for the Earth’s climate system, driving atmospheric and oceanic circulation, influencing weather patterns, and sustaining life through photosynthesis.2 This energy travels through space as electromagnetic waves, encompassing a broad spectrum of wavelengths, from high-energy gamma rays and X-rays to ultraviolet, visible, infrared, and radio waves. The portion of this spectrum that reaches the Earth’s surface is crucial for a multitude of processes, making thestudy of solar radiation fundamental to understanding our planet’s environment.  This introduction will lay the groundwork for exploring the characteristics, distribution, and interaction of solar radiation with the Earth’s atmosphere and surface.
5.1. Wave length of Radiation
The wavelength of radiation refers to the distance between two consecutive peaks or troughs of a wave. It’s a measure of the length of one complete cycle of the wave

3.1 The Sun

The Sun is a star. It is a huge, spinning, glowing sphere of hot gas. It appears so much larger and brighter than the other stars because we are so close to it. The Sun is the center of our Solar System and contains most of the mass in the Solar System. All of the planets in our Solar System, including Earth, orbit around the Sun. In sun the energy generation is a multi-step process of thermo-nuclear fusion reactions. In the thermo nuclear fusion hydrogen (four protons) combines to form helium (one helium nucleus). The mass of the helium nucleus is less than that of four hydrogen protons and mass having been lost in the reaction is converted to energy. The reaction is represented as

5.1 Introduction

Energy in the form of heat is one of the main energy requirements in domestic, agricultural, industrial and commercial sector of our economy. From an enduse point of view, solar thermal energy finds its application in these areas. Solar thermal energy devices convert radiant energy of the sun into thermal energy for different productive works. In fact, solar energy consists of infrared radiation, it is characteristics of infrared radiation that whenever it falls on any object, it converts into thermal heat energy.

The conversion of sun light into thermal energy is easily or conveniently achieved by means of a metallic or plastic cover, painted black with ordinary black board paint or having selected coating over it and covered with one- or double-glazing cover for transmitting solar radiation inside it. This metallic cover is known as absorber, below it either channels or pipes or passages for allowing entry of water or air are provided, through which heat energy is transferred to working medium either air or water. The absorber plate is covered with suitable thickness of insulating material on its back or sides for preventing loss of heat from the absorber plate. This complete system is enclosed in an airtight box. When exposed to solar radiations, the blackened metallic surface absorbs solar energy and converts into heat. This heat could be used for cooking of food, heating of water and air, evaporation of moisture form the grains etc. In fact, absorber works on the principle of black body, which absorbs maximum and a good absorber, is a good emitter. Hence generated heat could be utilized for different applications.

Introduction 
In a time when the world is in dire need of sustainable energy solutions, investigating biofuels becomes an essential path to supplying the always expanding supply[1]. This book chapter explores the dynamic world of solid and liquid biofuels, providing a thorough analysis of their properties, methods of production, uses, and wider ramifications in relation to renewable energy sources. Setting the scene, the introduction clarifies the role of biofuels in the larger context of renewable energy. Exploring solid and liquid biofuels becomes critical as the globe struggles with issues like climate change, depleting fossil fuel reserves, and the need to switch to cleaner energy sources[2]. These biofuels, which are defined as energy carriers made from biomass, offer a viable substitute and have the capacity to both reduce environmental impact and promote energy security. As the chapter progresses, biofuels are divided into two main categories: liquid and solid. Biofuels that are solid, such as wood, agricultural leftovers, pellets, and briquettes, serve as a starting point for investigating alternative energy sources. This section walks readers through the complexities involved in producing solid biofuel, including harvesting, pre-treatment, and creative pelletization methods. By doing this, it highlights the renewable nature of solid biofuels and their ability to lower greenhouse gas emissions, highlighting their benefits for the environment. Simultaneously, difficulties associated with its application, ranging from administrative worries to land use issues, are examined closely. Turning its attention to liquid biofuels, the chapter tells the story of ethanol, biodiesel, and advanced biofuels. By examining the choice of feedstock, manufacturing procedures, and real-world uses, it highlights the adaptability of liquid biofuels in the energy system. Although they are not without difficulties related to land use, food production, and water use, their ability to function with current infrastructure and their critical role in improving energy security stand out as distinguishing characteristics[3].

Introduction

One of the major problems being faced by cities and towns relate to management of municipal solid waste (MSW). Waste quantities are increasing day by day due to the increasing population and the municipal authorities are not able to upgrade or scale up the facilities required for proper management of such wastes. In many cities and towns, garbage is littered on roads and foot-paths. Citizens are also not accustomed to use the available storage facilities (dust bins) set up by the authorities. At large, lack of organized system of house- to-house collection of waste has created the littering habits. By and large, hardly we can see any city/town complying with the Municipal Solid Wastes (Management and Handling) Rules, 2000 in ‘totality”. As per information provided by Central Pollution Control Board (CPCB), 1,27,486 TPD (Tons per day) municipal solid waste was generated in the country during 2011-12. Out of which, 89,334 TPD (70%) of MSW is collected and 15,881 TPD (12.45%) is processed or treated.

In spite of various measures taken towards the proper waste collection, segregation and disposal, proper waste processing units were established as per the following details as per CPCB. The waste processing technologies reported in the country are; composting, vermi composting, biogas plant, RDF- pelletisation and others. Some of the sepelletization plants are associated with power plants for generation of electricity. However, mechanical composting and vermi composting are more popular in the country.

3.1. SOLID WASTE MANAGEMENT

Solid waste management includes the transportation, processing, recycling and disposal of our waste materials. We live in a disposable world in many ways with the modernization and convenience of our world we have cluttered it with our refuse.

Overview
Humanity has produced trash since the beginning of time, whether it is from the bones and other parts of the animals they kill for food or the wood they harvest to build their carts. As civilization developed, garbage was produced that was increasingly sophisticated in character. The world of consumers emerged around the close of the 19thcentury as a result of the industrial revolution. The production of non-biodegradable solid waste led to an increase in pollution not just in the air but also on Earth itself. The rise in solid waste was also primarily caused by urbanization and population growth.
Definition of Solid Waste
Glass crockery containers, plastic containers, sludge, vehicle parts, and mounds of crop wastes are among the solid waste materials. These gather in public areas and hinder people’s regular activities.
Every family produces waste or rubbish on a daily basis. We usually toss away items that we no longer need or have any use for, which puts them in the garbage category. Depending on where it comes from, solid waste can take several forms. Understanding the proper ways to handle the trash produced has become crucial in today’s dirty world. One crucial technique for managing municipal solid waste is segregation. Representation provides a good understanding of segregation at source. Composting is a crucial waste management and treatment technique.

Solid wastes are all the wastes arising from human and animal activities, that are normally solid and that are discarded as useless or unwanted materials. It consists of the highly heterogeneous mass of discarded materials from the urban community as well as the more homogenous accumulation of agricultural, industrial and mining waste.

Urbanization, industrialization, and economic growth in India have all led to an increase in the generation of municipal solid waste (MSW) by a number of urban local bodies (ULBs). In cities with high population densities, SWM is a significant difficulty. Being a diverse country with a wide range of religious communities, customs, and traditions like India makes it more challenging to accomplish sustainable development in a country that is rapidly industrialising and improving its standard of living. Although there have been substantial changes in the social, economic, and environmental spheres, India’s SWM systems have mostly remained the same. Currently, 90% of residual waste is thrown in the informal sector rather than properly disposed of. To make SWM more sustainable, new management practises and disposal sites are needed. The inefficiency of the current waste management systems has a detrimental effect on the economy, the environment, and public health. The Ministry of Environment and Forests of India introduced regulations for garbage treatment, although there is irregular and insufficient compliance.

Solid wastes, the unavoidable consequences of civilization, are the useless and unwanted heterogeneous solid materials discarded by human being. Human greed is the major factor in creation of unwanted solid wastes. With increase in human population and its demands, there is an increase in production of various types of wastes. When human being did not come to the earth there was very little wastes like tree leaves, animal excreta or dead parts which nature used to digest and produces something beautiful every time. Still there are certain remote areas free from wastes where human being could not reach due to inaccessible condition of terrain, forests and islands. Now–a-days wastes are found even in the top of Mt. Everest or in the interior of Antarctica.

India has witnessed a phenomenal increase in foodgrains production since Independence and from a food deficit state producing about 51 million tons in 195051 it become food surplus country with a record harvest of more than 250 million tons in 201112. This particular year also saw a remarkable record production of pulses at about 18.1 million tons. However, to meet the increasing demand of the continuously rising population about 23 million tons of pulses have to be imported every year costing the country about Rs.3000 crores in foreign exchange. Despite the changes in the dietary habits in which the large middle class has moved away from traditional cereals towards high value dairy, meat, fruits and vegetable products, pulses in India are still considered an important source of proteins, particularly for the poor. Pulses are not only an excellent source of protein (2040%), carbohydrates (5060%) and minerals (24%) but also provide calories almost equal to that of cereals energy to the tune of 300 to 540 Kcal/ 100g (Ofuya and Akhidue, 2005). Thus, pulses play an important role in achieving food and nutritional security for small and marginal farmers. However, the per capita availability of pulses has been declining over the time – it has declined from 60.7 gm/ day in 1951 to about 32 gm/day in 2010 – mainly due to stagnant production (except in recent years), rising demand for consumption and other uses. Pulses not only are used for consumption, but also play an even greater role in maintaining and enhancing soil fertility through nitrogen (N₂) fixation. Though the estimates of Nfixed by pulses depends on crop species, soil type, agroclimatic zone and crop management practices, it was reported that early, medium and long duration pigeonpea varieties fix 7, 55 and 69 kg/ ha¹, respectively, in Vertisols of Patancheru (Kumar Rao and Dart, 1987). Pulses ^N2 are grown not only as sole crops but also as intercrops and the biological nitrogen fixation (BNF) of pulses substantially benefits the associated or succeeding crops in terms of nitrogen contribution (1668 kg/ N₂ ha¹ for succeeding cereals). Thus on a conservative estimate, the BNF (@46 kg/N₂ ha¹) by pulses, excluding the intercrop area, alone amounts to 1.06 million tons annually.

North Eastern Himalayan Region comprises mostly of seven states viz. Arunachal Pradesh, Assam, Manipur, Meghalaya, Mizoram, Nagaland and Tripura (Gill, 2005). This Himalayan Region stands entirely different from the rest of the country not only in language, dress, food habits and festivals but also differs in agricultural practices. Among agricultural practices shifting cultivation locally known as ìJhumî or ìBunî is the most important. According to Ministry of Agriculture, Arunachal Pradesh stands first in the ìJhumî cultivation followed by Assam, Manipur, Meghalaya (Agnihotri, 2003). In Meghalaya, the problem has assumed an epidemic proportion in Gargo hills where tracts of forests are burnt. The farmers of Khasi and Jainta Hills usually practise the ìBunî cultivation.

Crop growth rate (g m^_-2 day^_-1)

Crop Growth Rate is referred to a whole crop, so you need to consider the area of the ground where crop is present. It is measured as mass increase in crop biomass per unit ground area per unit time.
Equation for that is, CGR= W₂-W₁ / t₁-t₂

In nature, microbes are found as a mixed population. The types that encounter the most favourable environmental and other growth conditions emerge in abundance while others that find the environment less favourable are fewer in number. However, for any kind of study on them or for their use as a pure species, they have to be separated from other species. The nutritional media or culture media are different for different species. As the medium is specific for certain species, it checks or restricts the growth of other microbes for which it may not be suitable. However, some growth of and contamination by unwanted species may occur.

Receiving student award from Dr IP Singh Dean Veterinary Sciences
Receiving student award from Mrs (Dr) Shinade Acting Vice-Chancellor
Dr Rajendra Prasad award of ICAR-2002 (Union Agriculture Minister Shri Ajit Singh is giving award to Prof RS Chauhan in the presence of Shri Hukum Dev Narayan Yadav Minister of state and Secretary agriculture)
Receiving “Gopal Gaurav award” from Shankaracharya Shri Raghvendra Saraswati ji maharaj of Shri Ramchandrapuram muth, Shimoga Karnataka ^^xksiky xkSjo** lEeku izkIr djrs gq,
Dr Jeff G Vos Congratulating Prof RS Chauhan on becoming advisor WHO at NIPHE Bilthoven, The Netherlands.
 Dr RS Chauhan is with the Union Agriculture minister Shri Sompal Shashtri ji in a function of Prakrati Bharti at Kota (Rajasthan)
Dr RS Chauhan is with the Union Science & Technology minister Shri Bachi Singh Rawat ji in a function of SIIP at CIMAP Lal kuan (Uttarakhand)

In meteorology, we often use some of the physical parameters to explain the physical processes taking place in the atmosphere. These parameters must have already appeared in the earlier chapters. However, these are given in this chapter to enable the readers to get acquainted once again.

16.1 Momentum

Momentum is defined as the product of mass and its velocity. In S.I. system units mass is expressed in kilograms and velocity in meters per second.

Momentum = Mass x Velocity

Units for momentum (S.I. system) = kg. m/sec

In C.G.S. System, mass is expressed in grams and velocity in cm/sec.

Units for momentum (C.G.S System) = gm.cm/sec