Important Single-Line Facts in Agricultural Meteorology

Basic Concepts

1. Father of Agricultural Meteorology – M.S. Swaminathan (India).
2. Father of Meteorology – Aristotle.
3. Father of Climatology – Vladimir Köppen.
4. Study of weather – Meteorology.
5. Study of climate – Climatology.
6. Study of agricultural weather relationships – Agricultural Meteorology.
7. Weather deals with – Short-term atmospheric conditions.
8. Climate deals with – Long-term average weather conditions (≥30 years).
9. Meteorology is derived from Greek words – “Meteoron” (things above the earth) and “logos” (study).
10. World Meteorological Day – 23rd March.

Atmosphere and Composition

1. Height of the atmosphere – ~10,000 km.
2. Troposphere height at equator – ~16 km; at poles – ~8 km.
3. Tropopause height – ~10–18 km.
4. Ozone layer is found in – Stratosphere.
5. Weather phenomena occur in – Troposphere.
6. Ozone absorbs – Ultraviolet (UV) radiation.
7. Major gases in atmosphere:
   • Nitrogen – 78%
   • Oxygen – 21%
   • Argon – 0.93%
   • CO₂ – 0.04%

8. Water vapor content – 0–4% by volume.
9. CO₂ concentration (2024) – Around 420 ppm.
10. Ozone (O₃) protects life from harmful solar radiation.

Solar Radiation

1. Solar constant – 1.94 cal cm⁻² min⁻¹ or 1367 W/m².
2. Albedo of Earth – About 30%.
3. Insolation – Incoming solar radiation.
4. Net radiation = Incoming – Outgoing radiation.
5. Shortwave radiation – From the Sun; Longwave radiation – From Earth.
6. Photosynthetically Active Radiation (PAR) – 400–700 nm.
7. Maximum solar radiation reaches Earth at – Noon.
8. Clouds reduce incoming solar radiation.
9. Reflection of solar energy by clouds and surface is called – Albedo effect.
10. Highest temperature of the day – Around 2–3 PM.

Temperature

1. Temperature lapse rate – 6.5°C per km in the troposphere.
2. Inversion of temperature – Temperature increases with height.
3. Isotherms – Lines joining equal temperature points.
4. Diurnal temperature range – Difference between day and night temperature.
5. Mean temperature = (Max + Min)/2.
6. Growing Degree Days (GDD) = (Tmax + Tmin)/2 – Base temperature.
7. Base temperature for wheat – 5°C; for rice – 10°C.
8. Thermal time concept – Used for crop growth prediction.
9. Soil temperature affects – Germination, root growth, microbial activity.
10. Temperature measurement instruments – Thermometer, Thermograph.

Wind

1. Wind is caused by – Pressure differences.
2. Measured using – Anemometer (speed), Wind vane (direction).
3. Unit of wind speed – m/s or km/h.
4. Coriolis force – Deflects wind direction due to Earth’s rotation.
5. Geostrophic wind – Balance between Coriolis force and pressure gradient.
6. Trade winds – Blow from subtropical highs to equatorial lows.
7. Monsoon winds – Seasonal reversal of wind direction.
8. Jet streams – Fast-moving air currents in the upper troposphere.
9. Anemometer – Invented by Leon Battista Alberti (1450).
10. Beaufort scale – Measures wind strength (0–12 scale).

Humidity and Evaporation

1. Humidity – Amount of water vapor in air.
2. Relative humidity (RH) = (Actual vapor pressure / Saturation vapor pressure) × 100.
3. Instrument to measure humidity – Hygrometer, Psychrometer.
4. Evaporation measured by – Class A Pan evaporimeter.
5. Transpiration – Loss of water vapor from plant surfaces.
6. Evapotranspiration (ET) = Evaporation + Transpiration.
7. Potential Evapotranspiration (PET) – Maximum ET under adequate moisture.
8. ET depends on – Temperature, wind, radiation, humidity.
9. Instrument to measure ET – Lysimeter.
10. Dew point – Temperature at which air becomes saturated.

Precipitation

1. Rainfall measured by – Rain gauge.
2. Unit of rainfall – Millimeter (mm).
3. 1 mm rainfall = 10,000 liters per hectare.
4. Types of rainfall: Cyclonic, Orographic, and Convective.
5. Monsoon rainfall in India – June to September.
6. Average annual rainfall in India – ~118 cm.
7. Drought – Deficiency of rainfall compared to normal.
8. Rain shadow area – Leeward side of mountains with low rainfall.
9. Rainfall distribution is more important than total rainfall.
10. India’s heaviest rainfall area – Mawsynram (Meghalaya).

Weather Phenomena

1. Cyclone – Low-pressure system with spiraling winds.
2. Anticyclone – High-pressure system with outward winds.
3. Tornado – Violent vortex of air from cumulonimbus cloud.
4. Fog – Suspension of water droplets reducing visibility.
5. Dew forms when – Temperature drops below dew point.
6. Frost forms when – Temperature falls below freezing point.
7. Hail – Frozen precipitation from cumulonimbus clouds.
8. Smog – Combination of smoke and fog.
9. Thunder and lightning – Associated with cumulonimbus clouds.
10. Cloud types – Cirrus, Cumulus, Stratus, Nimbus.

Agricultural Applications

1. Agrometeorology integrates – Weather, soil, and crop management.
2. IMD (India Meteorological Department) – Established in 1875.
3. Headquarters of IMD – New Delhi.
4. IMD issues Agromet Advisory Services (AAS) – For farmers.
5. Gramin Krishi Mausam Sewa (GKMS) – Provides weather-based agro advisories.
6. Crop weather calendar – Indicates critical crop stages and weather needs.
7. Forecast types: Short-range (1–2 days), Medium-range (3–10 days), Long-range (>10 days).
8. Weather forecasting models: Statistical and Numerical.
9. Satellite used for weather observation in India – INSAT, METSAT, Kalpana-1.
10. Remote sensing and GIS – Useful for drought and flood monitoring.

Climate Change and Agriculture

1. Greenhouse gases: CO₂, CH₄, N₂O, CFCs.
2. Major cause of global warming – CO₂ increase.
3. Kyoto Protocol signed in – 1997.
4. Paris Climate Agreement – 2015.
5. IPCC (Intergovernmental Panel on Climate Change) – Established in 1988.
6. Effect of global warming – Rise in temperature, erratic rainfall.
7. El Niño – Warming of Pacific Ocean leading to weak monsoon in India.
8. La Niña – Cooling of Pacific Ocean; leads to heavy monsoon.
9. Climate Smart Agriculture – Promotes adaptation and mitigation.
10. Agro-climatic zones in India – 15 (Planning Commission) / 20 (ICAR).