Climatology is the science of studying the average atmospheric conditions of a region in long-term perspective. The primary goal of Climatology is to study the unique characteristics of atmosphere in controlling the global climate, origin, types of climates, causes and processes influencing the climatic variations, elements of weather and the impact of climate on humans or vice-versa.

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SCOPE AND AIM OF STUDYING
CLIMATOLOGY
By Prof. A. Balasubramanian
Centre for Advanced Studies in Earth Science,
University of Mysore,
Mysore
Introduction:
The planet Earth is different from the other Planets of
the solar system. The presence of an atmosphere is a
unique feature supporting several things on earth.

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The air, sea and land constitute the major portions of
the three global spheres as Atmosphere, Hydrosphere
and Lithosphere. Climatology is one of the branches
of Earth and Atmospheric Sciences.
Climatology is the science of studying the average
atmospheric conditions of a region in long-term
perspective. The primary goal of Climatology is to
study the unique characteristics of atmosphere in
controlling the global climate, origin, types of
climates, causes and processes influencing the
climatic variations, elements of weather and the
impact of climate on humans or vice-versa.

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There are several branches involved in climatology as
Physical Climatology, Regional Climatology and
Applied Climatology.
Agricultural climate aviation climate, bio climate,
medical climate, macro climate, micro climate, meso
climate, Palaeo climate, Arctic climate.
The Physical Climatology is mainly concerned with
atmospheric phenomena and climates. Regional
Climatology deals with regional variations of climatic
conditions which include Micro climate, Local
climate, Meso Climate and Macro Climate.

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Applied Climatology deals with climatic controls of
human activities and the application of climatic
knowledge in solving unique problems faced by
human population. The root for climatology lies in
meteorology.
1. Elements of Weather and Climate: The term
weather refers to the sum total of short term variations
in atmospheric conditions in terms of temperature,
pressure, wind, water vapour, clouds, precipitation
and visibility. The term climate refers to the long-
term aggregate of weather conditions of a region (or)
the globe.

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The following are the elements of weather and
climate: Temperature, Air Pressure, Wind ,Humidity,
Precipitation, Cloudiness. These elements are
controlled by various factors like latitude, altitudes,
unequal distribution of land and water, air-sea
interface, ocean water circulation and
geomorphological conditions.
2. Structure and Composition of the Atmosphere:
The multilayered gaseous envelope attached to the
planet earth is the atmosphere. It is a unique sphere
of air, gases and water vapour.

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Under the umbrella of Climatology, the structure and
composition of the atmosphere are studied first. An
understanding of the thickness and disposition of
different layers like troposphere, stratosphere and
mesosphere are needed. The vertical variation in
temperature and concentration of gases have a
significant impact on global scales. The layer
concerning with weather and climate, is trophosphere.
Atmosphere is composed of three major constituents
as gases, water vapor and aerosols.

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Some are permanent (or) constant gases and some are
variable gases. They obey Boyle’s gas Law, Lussac’s
Law, Charle’s Law and combined gas law.
3. Insolation and Energy Balance : The Energy
system of the Earth involves, Solar Radiation, gravity
and geothermal sources. The Solar energy plays a
very significant role in heating the earth’s surface, and
the atmosphere. Because of these, it is responsible for
the movement of air and oceanic currents. The
radiant energy is the driving force for the global water
cycle, rock and the biogeochemical cycles.

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Without Sunlight, there is no photosynthesis in plants,
and there may not be any food for the other life.
Climatology involves the study of Insolation, Flow of
Energy, Absorption of radiation Emission of
Radiation , Distribution of Radiation, Heat Budget
(or) Energy balance, and Human influence on
radiation balance.
4. Atmospheric Temperature: Sun is the major
source of temperature in the atmosphere and also in
the oceans. Heating and Cooling of the atmosphere is
controlled by direct Sunlight.

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There is also a transfer of energy from the earth
through convection, conduction and re-radiation.
The processes of heating of the atmosphere are:
Convection -upward movement of air;
Conduction-High Temperature-Low temperature;
Radiation -a body emits radiant energy in the form of
heat. Re-radiation also heats the air.
Climatology involves the study of Transfer of heat
energy, Heating and Cooling of the atmosphere,
Mean Temperatures, Distribution of Temperature,

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Inversion of Temperature and Role of temperature in
other environmental segments like Hydrosphere and
biosphere.
5. Atmospheric Pressure and Motion: Air is
mixture of gases and hence has its own weight. Air
exerts pressure. Atmospheric pressure is maximum at
sea level. It decreases with increasing altitudes. Air
pressure varies vertically and horizontally. The
distribution of atmospheric pressure is controlled by
altitude, temperature, air circulation, earth’s rotation,
water vapour and other factors.

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Climatology studies the Pressure Gradient, Pressure
Types, Variations in atmospheric pressure.
Horizontal distribution of air pressure, Pressure belts
and shifting of Pressure belts, Atmospheric motion
and air circulation , Geotropic wind and Gradient
Wind , Wind direction and speed and Classification of
Wind.
6. Atmospheric circulation: The movement of air in
the atmosphere is known as atmosphere circulation.
Atmospheric circulation denotes the motion of air due
to pressure gradient from local to global scales.

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It has spatial and temporal patterns of circulation
components. Atmospheric circulation, speed and
direction of winds are controlled by Gravitational
force, Pressure gravitational force, Coriolis force,and
Friction force.
7. Local and Seasonal Winds: Wind is the
circulation of air relative to the surface of the earth.
Climatology analyses the local and seasonal winds in
detail. The periodic local winds include the breezes
between land and sea and the breezes from mountains
and valleys.

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The non-periodic local winds include the hot local
winds and Cold Local winds.Monsoon refers to the
annual cycle of dryness and wetness, with seasonally
shifting winds produced by changing atmosphere,
pressure systems. The study of Seasonal Winds
provides detailed large-scale information on
Monsoons. Seasonal characteristics of Monsoons
need to be analysed.
8. Atmospheric Humidity and Condensation: The
term Humidity refers to the amount of water vapour
present in a parcel of air having a unit volume and
temperature.

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Water Vapour is released during the process of
evaporation from water bodies of land and oceans.
Since water vapour is very important constituent of
the atmosphere, it plays a significant role in
controlling the climate.
It is present upto a height of 5 Km from the earth’s
surface.
Condensation is the process of converting Water
Vapour into liquid and solid forms.Atmospheric water
under goes phase changes through the exchange (or)
transfer of heat energy.

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9. Fogs, their origin and Types: Fogs are special
types of clouds consisting minute water droplets
existing in suspension in the air near the ground
surface. Fogs generally reduce the horizontal
visibility. Fog is formed when the moist air becomes
saturated and reaches its due point. Further cooling of
this mass make the water vapour to condense around
the dust particles and create the dense smoky Fog.
There are a dozen bases of classification available in
climatology to study the types of Fogs. The major
types of Fogs are also studied. Fogs are distributed in
different parts of the world.

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Climatology also analyses the effects of Fogs, and the
natural (or) Man induced dispersal of Fogs.
10. Clouds their origin and Types: Clouds are the
aggregates of innumerable tiny water droplets in the
atmosphere above the ground surface. Clouds are
formed due to condensation of water vapour. Global
patterns of precipitation depend on the clouds.
Clouds play a significant role in controlling the heat
budget of the earth’s surface.

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The study of clouds involved the Classification of
clouds and the Characteristic features of clouds. The
structure, altitude, occurrence and appearance of the
various types of clouds are studied in climatology.
11. Precipitation & its Distribution: The term
precipitation refers to the fall of atmospheric moisture
either in the form of liquids or solids. Climatology
includes the study of precipitation, its measurement
over space and time.

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The forms of precipitation includes rain, drizzle,
snow, ice pellets, hail, and sleet. Among these, rain is
the most wide spread form of precipitation.
12. Air Masses: The term Air Mass is used to
denote a large body of air whose dominant Physical
properties are more or less uniform horizontally and
vertically for hundreds of Km. Temperature and
moisture are the two major properties. Air mass
controls the weather conditions of an area. It plays a
major role in the transfer of energy in the atmosphere
through its movement.

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Air Masses are subjected to Thermodynamic and
Mechanical Modification. Due to these, air masses
are divided into cold air and warm air masses.
Climatology attempts to classify the air masses, based
on thermodynamic and geographical factors.
13. Atmospheric Disturbances: The term Air
Front is used to denote the sloping boundary between
two opposing air masses having contrasting physical
properties. These properties are temperature,
humidity, pressure and wind direction. Air fronts
differ from each other in terms of their location and
spread.

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The term Frontgenesis is used to describe the
processes of formation of new fronts, and decaying
old fronts. The conditions responsible for
frontgenesis are:
Temperature difference and Opposite directions of air
masses.
Air fronts are classified based on their characteristics
as Warm Front, Cold Front, Occluded Front and
Stationary Front.
Weather associated with warm and cold fronts are
also studied in Climatology.

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14. Extreme Events in Atmosphere: Extreme
events are those which are originated by natural or
human factors causing severe impact on the
environment like a hazard. These events exceed the
tolerable magnitude in the atmosphere causing
irreparable loss to life and properties. Atmospheric
extreme events include. Severe Storms, lighting,
hailstorm and thunderstorms. Cyclones are the
centres of low atmospheric pressure in which air
blows inwards in anticlockwise direction in the
northern hemisphere and clockwise direction in the
Southern hemisphere.

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Cycles are considered to be the major atmospheric
disturbances. Anticyclones are opposite in character
to those of cyclones. Tropical cyclones are low
pressure systems having a diameter of 650 Km
moving with an energy equivalent to 10000 atomic
bombs.
They are called as hurricanes in the North Atlantic
Ocean and as Typhoons in the North Pacific Ocean.
Climatology also includes the impacts of hazards and
their side effects like floods.
15. Classification of Climates: The world is rich
in holding many endless variety of climatic type.

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The factors that produce the climate in any given
place are called as climatic controls.
They are: Intensity of sunshine and its variation with
latitude, Distribution of land and water. Ocean
currents, Prevailing winds, Positions of high and low
pressure areas , Mountain barriers and Altitude. Both
Vertical and horizontal variation of climate are
analysed in Climatology.
World climates depend on the nature of parameters
like temperature and precipitation and their influence
over fauna and flora of ecosystems. Several climatic
zones have been identified so far.

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They are also classified based on empirical, numerical
and genetic approaches.
The important schemes are: Koppen’s multitiered
classification system, Thornthwaite’s Classification,
Genetic Classification and Composite Classification.
16. Climatic Types and Biomes: In the past,
climates were determined based on travel, regional
knowledge and latitude. An early attempt to classify
Earth’s climates was Aristotle’s temperature, torrid
and Frigid Zones. Today, climate classifications are
based on the causes and effects of climate.

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The World’s climate belongs to 3 major groups as
Tropical Climates, Middle Latitude Climates and
Polar and Highland Climates. There are several sub
climates identified based on location, temperature, air
pressure, winds, precipitation and effects of climate
on vegetation.
A biome is a large natural identical ecosystem having
unique assemblage of plant and animal communities
having a definite distributional patterns in terms of
climatic and soil conditions.

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17. Climatic Change: The climate is always
changing. Evidence shows that climate has changed
in the past And there is also evidences that It will also
change in future. Variation in Earth’s climatic
conditions are seen in both space and time. The
reason behind this variation is the dynamic nature of
atmosphere. Global climate may change due to
natural caused and man-made activities. The
changes may be cyclic and rhythmic.

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Climate change can adversely affect the lives of
millions.
The climatic controls interact to produce a wide
variety of different climates.
The indicators of climatic changes are Biological
Indicators (Floral, Faunal remain in fossils),
Geological Indicators (Sedimentary deposits),
Cryogenic Indicators (ice ages, glaciers, ice sheets),
Tectonic Indicators (Sea floor spreading and sea level
changes), Geomorphological Indicators , Historical
records of droughts and floods and migration of man
and animals.

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Dendrochronology is one aspect coming under these
analyses.
There are several theories and causes of climatic
changes. In Climatology all of them are studied to
understand the past and predict the future.
18. Global Warming and Atmospheric
Chemistry: The Global Warming refers to increase
in global surface and atmospheric temperature
affecting the global radiation balance. It comes due to
many anthropogenic activities leading to climatic
changes at local, regional and global levels.

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The increase in air-temperature and melting of ice
sheets and Glaciers are inter-related global
phenomena.
Ozone depletion due to various environmental factors
including the release of green house gases is the
causative mechanisms of Global Warming.
Emissions of carbon-di-oxide due to burning of fire
woods and fossil fuels increase in nitrous oxides and
methane due to various landuse changes and
agricultural practices affected the climatic parameters
of the atmosphere.

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The Global mean surface air temperature has
increased up to 0.60
C since the last century.
Global sea level has risen by 25 cm over the past 100
years. All of these have modified some portions of
atmospheric chemistry, which have shown several
environmental effects as a consequence.
19. Weather Forecasting: Weather Forecasting is
a major field of predicting the weather conditions
comprising the temperature of atmospheric air,
movement of wind, humidity, sunshine hours,
cloudiness, precipitation and atmospheric

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disturbances over a place or region, well in advance.
Different sources of weather and climatological data
are collected on daily, weekly, monthly and annual
bases from global network of observatories and used
to forecast.
Global life is fully dependent on the knowledge of
weather for carrying out various domestic and
industrial activities.
Weather watch is a forecast indicating that
atmospheric conditions are favourable for hazardous
weather to occur over a particular region during a
specified time period.

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20. Climatologists evaluate
1) long-term weather conditions of a vast region over
a long period of time.
2) Climate and its distribution on the earth’s surface,
horizontally and vertically
3) The effects of human activities on different
components of the atmospheric conditions including
weather and climate, and
4) The role of climate and weather on the biosphere
and hydrosphere.