The agriculture sector is the backbone of all countries’ economies and is responsible for about one fourth of the gross domestic product. Weather plays a significant role in agriculture, shaping the growth and productivity of crops. As our atmosphere changes, severe weather that has the potential to destroy crops has become more and more frequent. Accurate weather information’s provides valuable insights into weather patterns, enabling farmers to make knowledgeable decisions and optimize their agricultural practices. This book provides a comprehensive understanding of weather and climate and their impact on crop production. This book attempts to present current, up-to-date information on agricultural meteorology with appropriate illustrations. The book covers essential topics, such as Earth’s Atmosphere, Earth Sun Relationship, Earth’s Coordinate System and Time Zones, Weather and Climate, Solar Radiation, Visible Light, Heat and Temperature, Atmospheric Pressure, Wind, Air Masses and Atmospheric Fronts, Evapotranspiration, Atmospheric Humidity, Clouds, Precipitation, Monsoon, Meteorological Aberrations, Smart Weather Stations, Remote Sensing, Crop simulation models for preparation of Agro advisory, Agro-climatic Normal for Crop and Livestock Production, Weather modification, Climate Classifications & Agro-climatic Zones, Weather Forecasting and Global warming and Climate Change in relation to agriculture. Technological advancements to improve the accuracy of agricultural weather data are important to support modern agriculture. This book also includes practical observational methods for each weather element using weather-measuring instruments. It has been helping to meet the requirements of undergraduate and post-graduate students and doctoral scholars of agriculture and allied sciences. Updated with recent research and practical examples, it aligns with the syllabus prescribed by ICAR for agriculture and allied sciences. An additional objective is to provide updated and relevant knowledge for aspirants of various competitive examinations. I trust that this book will serve as a valuable resource for agronomists, soil scientists, crop scientists, extension specialists, farmers, and all others with an interest in agricultural meteorology.
R. Rex Immanuel, M.Sc. (Ag)., Ph.D. Assistant Professor Department of Agronomy Agricultural College & Research Institute Tamil Nadu Agricultural University Vazhavachanur - 606 753 Tamil Nadu, India.
1 INTRODUCTION .........................................................................................................................................1
Branches of Meteorology ...............................................................................................................................3
Meteorologists.................................................................................................................................................4
Modern Meteorological Science and Technology......................................................................................5
History of Meteorological Services in India ...............................................................................................7
Significance of Agrometeorology .................................................................................................................8
Scope of Agricultural Meteorology .............................................................................................................9
2 PLANET EARTH .........................................................................................................................................13
3 EARTH’S ATMOSPHERE .........................................................................................................................19
Layers (Stratification) of Earth’s Atmosphere ..........................................................................................19
4 EARTH-SUN RELATIONSHIP ................................................................................................................25
Earth’s Rotation ...........................................................................................................................................25
Earth’s Revolution .......................................................................................................................................26
Solstices .........................................................................................................................................................27
Equinox .........................................................................................................................................................28
Latitude ..........................................................................................................................................................29
Astronomical Seasons .................................................................................................................................30
Traditional Indian Seasons ........................................................................................................................33
5 EARTH’S COORDINATE SYSTEM AND TIME ZONES .................................................................35
Cartesian Coordinates .................................................................................................................................35
The Geodetic (Latitude/Longitude) Coordinate System .......................................................................38
Identifying a Location on Earth .................................................................................................................40
Longitude and Time .....................................................................................................................................41
Coordinated Universal Time (UTC) ..........................................................................................................41
India Time Zones ..........................................................................................................................................44
6 WEATHER AND CLIMATE .....................................................................................................................51
Factors Influencing the Weather ................................................................................................................51
Factors Affecting Climate ............................................................................................................................53
Climate Classification ..................................................................................................................................55
Scales of Meteorology ..................................................................................................................................59
Meteorological Observatory .......................................................................................................................62
7 SOLAR RADIATION .................................................................................................................................67
Characteristics of Electromagnetic Waves ................................................................................................67
Radiation Laws .............................................................................................................................................69
Factors Affecting Insolation .......................................................................................................................72
Solar Constant ...............................................................................................................................................73
Solar Spectrum and Its Distribution ..........................................................................................................74
Albedo ............................................................................................................................................................78
Radiation Influence on Atmosphere and Plant Life ................................................................................83
Spectral Composition of Radiation in a Plant Canopy ...........................................................................92
8 VISIBLE LIGHT ..........................................................................................................................................85
Functions of Light ........................................................................................................................................86
Solar Radiation and Photosynthesis ..........................................................................................................91
Light Compensation Point ..........................................................................................................................93
Light Saturation Point ..................................................................................................................................93
Factors Influencing the Distribution of Solar Radiation within the Plant Canopy ............................94
Measurement of Solar radiation ................................................................................................................95
Actinometers .................................................................................................................................................95
Pyrheliometer ...............................................................................................................................................96
Pyranometers ................................................................................................................................................97
Pyrgeometers ..............................................................................................................................................101
Net Radiometer ...........................................................................................................................................101
Albedometers ..............................................................................................................................................102
Campbell-Stokes Sunshine Recorder ......................................................................................................103
Measurement of Photosynthetically Active Radiation .........................................................................107
9 HEAT AND TEMPERATURE ...............................................................................................................109
Heat Transfer Processes.............................................................................................................................110
Temperature Variations ............................................................................................................................111
Isotherms .....................................................................................................................................................114
Factors Contribute to Horizontal Temperature Variations ..................................................................115
Temperature Inversion or Thermal Inversion .......................................................................................116
Factors Affecting Temperature Inversion ...............................................................................................118
Adiabatic Processes ....................................................................................................................................119
Factors Affecting Atmospheric Temperature .........................................................................................121
Role of Temperature on Crop Production ..............................................................................................122
Thermoperiodism .......................................................................................................................................125
Cardinal Temperature ...............................................................................................................................125
Thermal Death Point ..................................................................................................................................127
Van’t Hoff’s Law or Temperature Coefficient (Q10) ............................................................................127
Thermal Time/Growing Degree Days ....................................................................................................128
Soil Temperature ........................................................................................................................................131
Factors Affecting Soil Temperature .........................................................................................................132
Effect of Soil Temperature on Crop Production ....................................................................................133
Weather Instrument Shelter ......................................................................................................................135
Maximum Thermometer ...........................................................................................................................137
Minimum Thermometer ............................................................................................................................138
Temperature Sensors .................................................................................................................................140
Thermograph ..............................................................................................................................................140
Soil Thermometer .......................................................................................................................................141
Soil Temperature Probe .............................................................................................................................142
Grass Minimum Thermometer .................................................................................................................143
Grass Minimum Temperature Sensor .....................................................................................................144
Canopy Temperature Measurement and Stress Degree Days (SDD) .................................................145
10 ATMOSPHERIC PRESSURE ..................................................................................................................147
Variation in Atmospheric Pressure .........................................................................................................149
Global Atmospheric Pressure Systems ..................................................................................................152
Seasonal Atmospheric Pressure Variation ..............................................................................................156
Isobars ..........................................................................................................................................................150
Isallobars ......................................................................................................................................................152
Factors Responsible for Variation in the Distribution of Atmospheric Pressure ..............................158
Effect of Atmospheric Pressure on Crop Production ............................................................................159
Measurement of Atmospheric Pressure ..................................................................................................159
Torricelli Barometer ...................................................................................................................................159
Fortin Barometer .........................................................................................................................................160
Aneroid Barometer .....................................................................................................................................161
Aneroid Barograph ....................................................................................................................................162
Barometric Pressure Sensors .....................................................................................................................163
11 WIND ...........................................................................................................................................................165
General Circulation of Air .........................................................................................................................165
Types of Winds ...........................................................................................................................................166
Calm Wind Zones .......................................................................................................................................168
Cyclonic Winds ...........................................................................................................................................173
Nomenclature of Tropical Cyclones ........................................................................................................181
Extratropical Cyclones ...............................................................................................................................183
Isotach .........................................................................................................................................................185
Factors Affecting Wind ..............................................................................................................................186
Effect of Wind on Plants ............................................................................................................................187
The Beaufort Scale ......................................................................................................................................188
The Saffir-Simpson Hurricane Wind Scale .............................................................................................189
RSMC-NIO Cyclone Classification Scale ................................................................................................190
Dvorak Technique ......................................................................................................................................191
Colour-coded Cyclone Warning System.................................................................................................195
Visual Cyclone Warning Signals .............................................................................................................195
Tornado Intensity Scales ...........................................................................................................................197
Measurement of Wind Direction and Speed ..........................................................................................198
Wind Vane ...................................................................................................................................................199
Anemometer ...............................................................................................................................................200
Anemograph ...............................................................................................................................................201
Ultrasonic Wind Speed and Direction Sensor ........................................................................................203
Wind rose ....................................................................................................................................................206
12 AIR MASSES AND ATMOSPHERIC FRONTS .................................................................................209
Source Regions of the World’s Principal Air Masses ............................................................................209
Classification of Air Masses ......................................................................................................................210
Atmospheric Fronts ...................................................................................................................................213
13 EVAPOTRANSPIRATION .....................................................................................................................221
Evaporation .................................................................................................................................................223
Factors Affecting Evaporation ..................................................................................................................223
Transpiration ..............................................................................................................................................224
Factors Affecting Transpiration ...............................................................................................................224
Types of Evapotranspiration ....................................................................................................................226
USWB Class A Open Pan Evaporimeter .................................................................................................230
Volumetric lysimeter .................................................................................................................................234
Gravimetric lysimeters ..............................................................................................................................235
14 ATMOSPHERIC HUMIDITY ................................................................................................................239
Types of Humidity .....................................................................................................................................239
Effects of Humidity on Plant and Animals Life .....................................................................................242
Hair Hygrometer .......................................................................................................................................243
Simple or Stationary Psychrometer (Wet and Dry Bulb Thermometer) ............................................244
Hair Hygrograph ........................................................................................................................................245
Assmann Psychrometer .............................................................................................................................246
Relative Humidity Sensors .......................................................................................................................247
15 CLOUDS ....................................................................................................................................................251
Significance of Clouds ...............................................................................................................................251
Cloud Development Mechanisms............................................................................................................252
Cloud Classification and Its Latin Nomenclature ................................................................................255
Measurement of Cloud ..............................................................................................................................260
16 PRECIPITATION ......................................................................................................................................263
Forms of Precipitation ...............................................................................................................................264
Types of Precipitation ...............................................................................................................................265
Thunderstorm .............................................................................................................................................268
Isohyet ..........................................................................................................................................................271
Isobront ........................................................................................................................................................271
Hailstorm ....................................................................................................................................................271
Hailstorm Intensity Scale ..........................................................................................................................272
Effect of Precipitation on Agriculture .....................................................................................................276
Ordinary Rain Gauge or Symon’s Rain Gauge ......................................................................................278
Self-recording Rain Gauge (Siphon Rain Gauge) ..................................................................................279
Tipping Bucket Rain Gauge ......................................................................................................................281
Pluvio-Universal Precipitation Gauge ....................................................................................................281
Disdrometer ................................................................................................................................................282
Hail Sensor ..................................................................................................................................................285
Presentation of Rainfall Data ....................................................................................................................288
Rainfall Probability Analysis ....................................................................................................................288
Standard Deviation and Co-efficient of Variation .................................................................................289
Trend Analysis ............................................................................................................................................291
Hyetograph ................................................................................................................................................293
Rainfall Criteria Suitability for Rainfed Crops .......................................................................................294
Growing Period Analysis ..........................................................................................................................297
Probability Analysis of Rainfall for Rainfed Crop Planning ................................................................304
17 MONSOON ................................................................................................................................................307
Factors Responsible for the Formation and Progression of the Indian Summer Monsoon ............309
Onset of the South-West Monsoon ..........................................................................................................314
Low Pressure Systems ..............................................................................................................................319
Monsoon Trough ........................................................................................................................................321
Weak / Break Monsoon Conditions ........................................................................................................323
North-East Monsoon .................................................................................................................................326
Withdrawal of North East Monsoon .......................................................................................................336
Western Disturbances ................................................................................................................................336
Characteristics of Seasonal Rainfall ........................................................................................................339
Monsoon Rainfall Variability ...................................................................................................................341
Effective Rainfall .........................................................................................................................................342
Global-atmospheric Phenomena and its Relationship with Indian Monsoon ..................................345
18 METEOROLOGICAL ABERRATIONS ...............................................................................................353
Impacted Extreme Weather Events .........................................................................................................353
Lightning and Thunderstorms ................................................................................................................355
Microbursts .................................................................................................................................................358
Extremely Heavy Rainfall, Floods and Landslides ...............................................................................358
Cloud Burst .................................................................................................................................................358
Tropical Cyclones ......................................................................................................................................359
Hailstorm .....................................................................................................................................................366
Tornado ........................................................................................................................................................368
Flood .............................................................................................................................................................369
Landslide .....................................................................................................................................................370
Drought .......................................................................................................................................................370
Dust Storms .................................................................................................................................................377
Heat Waves .................................................................................................................................................378
Cold Waves .................................................................................................................................................380
Blizzard .......................................................................................................................................................381
19 SMART WEATHER STATIONS ...........................................................................................................383
Types of AWS ............................................................................................................................................384
Components of an AWS ............................................................................................................................384
Third-generation AWSs (Smart Weather Stations) ...............................................................................389
Multi-parameter Compact Smart Weather Station ...............................................................................390
IoT (Internet of Things) in AWS ...............................................................................................................391
20 REMOTE SENSING .................................................................................................................................393
Principal Stages in Remote Sensing System ...........................................................................................393
Atmospheric Windows ..............................................................................................................................394
Bands used in Remote Sensing/Weather Satellites ..............................................................................395
Fundamental Techniques used in Remote Sensing ...............................................................................400
Spectral Signature.......................................................................................................................................401
Approaches in Remote Sensing Techniques ..........................................................................................403
Remote Sensing Platforms and Sensors ..................................................................................................405
Doppler Radar Networks in India ...........................................................................................................419
Drones .........................................................................................................................................................421
Drone Sensors .............................................................................................................................................422
Factors Influencing the Quality of Remote Sensed Images ..................................................................423
21 CROP SIMULATION MODELS FOR PREPARATION OF AGRO-ADVISORY .......................435
Crop-weather Model ..................................................................................................................................437
Model Approaches .....................................................................................................................................439
22 AGRO-CLIMATIC NORMAL FOR CROP AND LIVESTOCK PRODUCTION ........................453
23 WEATHER MODIFICATION ................................................................................................................459
Artificial Rain Making (Cloud Seeding) .................................................................................................459
Seeding Techniques for Cold Clouds ......................................................................................................462
Seeding Techniques for Warm Clouds ....................................................................................................462
Fog Dispersal ..............................................................................................................................................464
Hail Suppression ........................................................................................................................................464
Lightning Suppression ..............................................................................................................................465
Microclimate Modification ........................................................................................................................465
24 CLIMATE CLASSIFICATIONS & AGRO-CLIMATIC ZONES .....................................................469
Koppen Climate Classification .................................................................................................................469
Climate Classification by Alisov ..............................................................................................................474
Thronthwaite and Mather ........................................................................................................................477
Modified Troll’s ..........................................................................................................................................478
Hargreaves Method (1971) ........................................................................................................................478
Classification of Climate based on Aridity Index ..................................................................................479
Agro-climatic Regions by the Planning Commission of India ............................................................481
Agro-climatic Zones under National Agricultural Research Project (NARP) ..................................483
25 WEATHER FORECASTING ...................................................................................................................489
Significance of Weather Forecasting ........................................................................................................491
Indigenous Technical Knowledge (ITK) for Weather Forecasting .....................................................494
Modern Weather Forecasting ...................................................................................................................496
Classification of Weather Forecasting Models .......................................................................................499
Nowcasting and Its Application ..............................................................................................................499
Nowcasting Tools .......................................................................................................................................500
System for Thunderstorm Observation, Prediction and Monitoring (STORM) ...............................503
Nowcast Warnings in Terms of Colour Codes ......................................................................................504
Nowcast Models used over Indian Region ............................................................................................505
Very Short-Range Forecast (VSRF) ..........................................................................................................507
Short-Range Weather Forecasting ...........................................................................................................508
Medium-Range Weather Forecasting ......................................................................................................508
Extended-Range Weather Forecasting ....................................................................................................508
Long-Range Weather Forecasting ............................................................................................................509
Classification of Weather Forecasting Models based on the Methodology Employed ...................510
Dynamical Models (Numerical Weather Prediction) ...........................................................................511
Ensemble Prediction Systems ...................................................................................................................514
Artificial Intelligence (AI) and Machine Learning (ML) on Weather Forecasting ............................517
Hybrid Models ............................................................................................................................................519
Global Weather Models .............................................................................................................................520
Weather Models used in India .................................................................................................................523
Synoptic Observations ...............................................................................................................................528
Standard Hours of Observations .............................................................................................................536
Value Addition ..........................................................................................................................................537
Forecast Verification ..................................................................................................................................538
Weather Charts ..........................................................................................................................................543
Weather Symbols .......................................................................................................................................545
Surface Weather Station Plots/ Models ..................................................................................................545
Smartphone Weather Applications .........................................................................................................552
IMD and Its Role in Weather Forecasting ...............................................................................................557
All India Coordinated Research Project on Agrometeorology (AICRPAM) .....................................559
Monsoon Mission .......................................................................................................................................559
Mahalanobis National Crop Forecast Centre .........................................................................................561
Forecasting Agricultural Output using Space, Agrometeorology and Land (FASAL) ...................561
NADAMS (National Agricultural Drought Assessment and Monitoring System) .........................563
Agromet Forecasting and Research Center ............................................................................................564
Impact Based Forecast (IBF) - Heavy Rainfall ........................................................................................564
WINDS Initiative for Hyperlocal Weather Forecasting ........................................................................565
RAPID ..........................................................................................................................................................566
National Centre for Medium Range Weather Forecasting (NCMRWF) ...........................................567
Monsoon Forecast in India ........................................................................................................................569
Agrometeorological Advisory Services (AAS) in India .......................................................................570
Gramin Krishi Mausam Sewa (GKMS) ...................................................................................................571
District Agro-Met Units (DAMU) ............................................................................................................571
Agromet - Decision Support System .......................................................................................................571
Agro-met Advisory Bulletins ...................................................................................................................572
Dissemination of Weather Forecasting ...................................................................................................577
Crop weather calendar ..............................................................................................................................578
Indian Institute of Tropical Meteorology (IITM) ...................................................................................583
26 GLOBAL WARMING AND CLIMATE CHANGE ............................................................................585
Glossary ......................................................................................................................................................627
References ..................................................................................................................................................641
