Meterology

Communication Series
Agricultural Meteorology
By Shiv singh yadav
THE STUDY sapnacsauat@gmail.com
BY SHIV SINGH YADAV MOB; 8381912586

❏ Meteorology is the science of Atmosphere and its attendant activities
❏ The word “metrology” is from Greek meteoros , “ high in the sky” and logia
“ Study”.
❏ It is defined as the physics of the weather phenomena.
METEOROLOGY

AGROMETEOROLOGY
❏ It is a branch of meteorology , which investigates the relationship of plants and animals to
the physical environment.
❏ The meeting of agroclimatologists in Moscow during 1951 defined agrometerology.
The study sapnacsauat@gmail.com
By - shiv singh yadav Mo 8381912586

CLIMATOLOGY
❏ The word “climatology” comes from Greek words klima , “ slope of the earth “
and logia “ study “.
❏ Climatology is the science dealing with the factors which determine and
control distribution of climate over the earth’s .

AGROCLIMATOLOGY
❏ Agroclimatology can be defined as the science that deals with the aspects of
climatology having direct relative to agriculture. It seeks to relate climatic
regimes to Agricultural production.

WEATHER
❏ Weather is a state or condition of atmosphere at a given place and at a given
time.
❏ Weather is expressed by numerical values of meteorological parameters.
❏ Examples of weather are hot day, rainy day, cloudy weather, dry weather etc.

CLIMATE
❏ Climate is generalized weather or summation of weather conditions over a
given region during a comparatively longer period.
❏ Climate is weather conditions related to larger areas like zone, state, country,
part of continent or whole of continent, longer duration of time like month,
season or year.
❏ Climate is expressed by normals and averages e.g., cold season, tropical
climate etc

ATMOSPHERE
❖ It is a colorless , tasteless and odorless mixture of gases that suround the
earth.
❖
● Atmosphere extends up to a height of about 1600 km.
● 99 per cent of total atmospheric mass is within 40 km from the earth surface.
● Volume of Nitrogen in atmosphere is 78%.
● Weight of Nitrogen in atmosphere is 75.5%.
● Volume of Oxygen in atmosphere is 21%.
● Weight of Oxygen in atmosphere is 23.1%.

● Volume of Argon in atmosphere is 0.93%.
●
● Weight of Argon in atmosphere is 1.28%.
●
● Volume of Carbon dioxide in atmosphere is 0.03%.
●
● Weight of Carbon dioxide in atmosphere is 0.045%.
●
● Volume of water vapour in lower layer of atmosphere is 0 to 4%.
the study sapnacsauat@gmail.com

ATMOSPHERE
❖ . troposphere,
❖ Stratosphere,
❖ mesosphere
❖ Thermosphere.
➔
➔ Based on vertical temperature differences atmosphere is divided into 4 layers

1. TROPOSPHERE
● Troposphere is the lower layer of atmosphere.
● Troposphere extends up to a height of 8 to 18km from earth surface depending on latitude.
● 8 km from polar and 18 km from equator.
● Troposphere is thicker at equator than poles.

● Troposphere contains 85% of atmospheric mass.
● Weather phenomenon like clouds, fog, dew, mist, rain etc. occur in
troposphere.(IARI)
● Temperature decreases with increase in altitude at the rate of 6 c*/km
● Tropopause is a thin layer between troposphere and stratosphere.

2.STRATOSPHERE
● Stratosphere layer lies above tropopause
.
● Stratosphere lies beyond 8 to 18 km extending up to 50km depending on
latitude.
● Stratosphere is dustless, cloudless and warmest layer.
● Temperature increases with height in stratosphere.

● Stratosphere contains 15% of atmospheric mass.
● Stratosphere has low density of gases.
● Mass of air up to 40 km is more than 99% of total atmospheric mass.
● Due to presence of Ozone layer UV rays are absorbed , hence it is also
called Ozonosphere.
● Most of concentration of ozone is present about a height of 25 km from the
earth surface.

3. MESOSPHERE
● Stratopause separates stratosphere and mesosphere.
● Mesosphere is the layer that lies above stratosphere.
● In mesosphere temperature decreases with increase in altitude up to 80km.
● Cold region .
● Mesopause separates mesosphere from thermosphere.

4. THERMOSPHERE
● Thermosphere is the outer layer of atmosphere.
● From earth surface it is extending a height of 80 km up to 1600 km .
● The lower layer of atmosphere is called ionosphere
● It is outermost layer is called exosphere
● Temperature increase with altitude.
● Long distance radio communication is made possible through this ionized
layer.

Solar constant
❖ Solar constant is defined as the energy falling in one minute on a surface area
of one square centimeter at the outer boundary of atmosphere held normal to
the sunlight at the mean distance of the earth from the sun.
❖ Value of solar constant is 1.94 cal /cm2/min. Or SI Unit is : 1353 Watts /m2
❖ The solar radiation is received in the form of electromagnetic waves particles
are called quanta or photons.

➔ Direct solar radiation is the radiation received directly from sun by a surface
normal to the incident radiation.
➔ Diffused radiation or sky radiation is the radiation scattered by suspended
particles in the atmosphere.
➔ • Quantity of diffused radiation depends on latitude, season and cloudines.

➔ In high latitudes diffused radiation is important source of solar radiation
and forms substantial part of solar radiation during winter months.
➔ Cloudiness increases ratio of diffused to direct radiation
➔ Before sunrise and after sunset all the solar radiation received is diffused or
sky radiation.

➔ In plant canopies diffused radiation penetrates effectively than direct
radiation.
➔ Diffused radiation contains 65% photosynthetically active radiation
(PAR).
➔ Direct radiation contains 42% photosynthetically active radiation (PAR

PHOTOSYNTHETIC ACTIVE RADIATION
❏ Photosynthesis in green leaves use solar energy in wavelengths from 0.4 to
0.7 um or the radiation 400-700 nm is most active in photosynthesis is known
as (PAR).
❏ PAR or photons are measured by Quantum sensor.
❏ Lux is oldest unit of solar radiation .

➔ Photosynthetic active radiation (PAR) is measured in Einstein units.
➔ 1 Einstein unit = 1 mole of photons
➔ Total incoming radiation measured by pyranometer.
➔ Diffused radiation measured by shading pyranometer

LAPSE RATE
● The vertical temperature decrease or gradient is expressed as lapse rate.
● Normally lapse rate is 6.5 *c /km.
● Normal lapse rate is 6.5oC per km or 3.5oF per 1000 feet.

ADIABATIC LAPSE RATE
● The rate at which the temperature changes as air rises or falls is called
Adiabatic lapse rate ‘.
● Dry adiabatic lapse rate ;; 10 *c/km.
●

ALBEDO
❖ It is ratio between incoming and outgoing solar radiation on the earth surface.
❖ It is the percentage of the incidence solar radiation reflected by a surface is
known as albedo.
❖ It is expressed in percentage.

● The albedo of crop surface is ranging between 23-30 %
.
● The albedo for fresh snow is ranging from 75-95 .
● Reflected radiation is measured by albedometer.
● Albedo or reflected solar radiation is the solar radiation that is reflected
without any change in its quality.

➔ • Clouds are effective reflectors of solar radiation.
➔ • Snow is a very effective reflector, particularly when it is fresh.
➔ • Water surfaces and sea are poor reflectors.
➔ • Rocks, sand, soil and vegetation reflect from 10 to 30 percent of the
incident solar radiation.
➔ • Reflected solar radiation is important in remote sensing.

➔ Earth absorbs solar radiation in short waves and emits back in the form of
long waves.
➔ Terrestrial radiation heats the atmosphere.
➔ Net radiation is the radiation balance between global and reflected solar
radiation.

➔ Net radiation is measured by net radiometer.
➔ Direct solar radiation is measured by pyrheliometers.
➔ Pyrgeometer is used to measure terrestrial radiation.
➔ Sunshine hours recorded by sunshine recorder.

➔ Height of sunshine recorder from ground surface is 3.08 .
➔ Height of Stevenson screen from ground surface is 1.22 m.
➔ Day and night are equal all over the world, with the sun right over the
equator.

➔ • Solar radiation in narrow wave bands is measured by Spectroradiometer.
➔ Infrared thermometer measures temperature of canopy without contact.
➔ Infrared thermometer is used to estimate water status of plants and also to
schedule irrigation.

➔ Temperature is the degree of hotness or coldness of a substance determined
by its molecular activity.
➔ Temperature is measured by thermometer.
➔ Depth of water table is measured by Piezometer.
➔ • Conduction is transfer of heat by molecular activity.

➔ Convection is process of heat transfer within liquids and gases resulting
from the motion of fluid.
➔ • Convection is faster than conduction.
➔ • Radiation is transfer of energy by electromagnetic waves moving at the
speed of light.

➔ X-rays are short.
➔ Radio waves are long
.
➔ • On an average cloudy day 43% solar radiation absorbed by earth, 22%
by atmosphere and 35% reflected into space from earth.

➔ Reflected solar radiation is unchanged in character.
➔ Solar radiation absorbed by earth or atmosphere is converted into thermal
energy.
➔ Solar radiation is more at 12 noon, whereas highest temperature is noticed
2 P.M.

➔ At equator seasonal temperature variation is less.
➔ Seasonal variation in temperature is more at higher latitudes.
➔ Isotherms are the lines that connect points of equal temperature

➔ Thermal conductivity decreases with increase in porosity.
➔ When soil is ploughed, it increases soil porosity and reduces thermal
conductivity.
➔ Thermal conductivity increases with increase in moisture content.
➔ Soil organic matter lowers thermal conductivity.

➔ Thermal conductivity higher in sandy soils than clay soils due to less
porosity in sandy soils compared to clay soils.
➔ Temperature is measured in Celsius, Fahrenheit or Kelvin scales.
➔ In Fahrenheit scale melting point of water is 32oF.

➔ In Fahrenheit scale boiling point of water is 210oF.
➔ In Celsius scale melting point of water is 0oC.
➔ In Celsius scale boiling point of water is 100oC.
➔ Absolute temperature is measured by Kelvin scale.

➔ Melting point of water in Kelvin scale is 273oK.
➔ Maximum thermometer is used to measure highest temperature of a day.
➔ Maximum thermometer is set in the morning time.

➔ Minimum thermometer is used to measure lowest temperature of a day.
➔ Minimum thermometer is set in the evening time.
➔ Thermocouple is used to measure soil temperature.
➔ Thermograph is used to record air temperature continuously.

➔ barograph are used for measuring atmospheric pressure.
➔ Standard international unit of pressure is Pascal.
➔ One Pascal is equal to force of one Newton m-2.

➔ Wind velocity is measured by anemometer.
➔ Density of gases is measured by aerometer.
➔ Specific gravity of liquids is measured by hydrometer
.
➔ Pycnometer is used to measure specific gravity of liquids.

➔ Direction from which wind blows is called windward side.
➔ Direction towards which wind blows is called leeward side.
➔ Wind direction is measured by windvane.

THANKS
AGRICULTURAL METEOROLOGY PART - 1
❖ Those people who are not longer in this world also
helped in preparing this pdf.
❖
the study sapnacsauat@gmail.com
Thanks for Dr. Dinesh sir
Your suggestions are cordially invited

Meterology

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