Climatology

470 Pages·2006·31.597 MB·English

by  Savindra Singh

■ r •
CHAPTER 1 : CLIMATOLOGY : BASIC CONCEPTS I'M
Climatology : a part of physical geography ; t
climatology : an atmospheric science (aerology, meteorology, climatology); t
climatology : types and subdivisions (dynamic climatology, regional
climatology, applied climatology and satellite climatology); 3
aims and scope of climatology ; 6
climatology : a historical perspective; 7
elements of weather and climatej, 13
controls of weather and climate. 13
1
CLIMATOLOGY : BASIC CONCEPTS
1.1 CLIMATOLOGY : A PART OF PHYSICAL changes of environmental components and causes
GEOGRAPHY thereof (Savindra Singh, 2003).
It may be mentioned that on an average
Physical geography is one of the two major
physical geography includes the consideration of
branches of geography, namely physical geog­
various aspects of four components of the earth
raphy and human geography. Physical geography
e.g. (i) lithosphere (geomorphology), hydrosphere
was previously considered as the agglomeration
(oceanography), atmosphere (meteorology and
of different branches of earth sciences or natural
climatology), and biosphere (biogeography—
sciences such as the science of atmosphere
environmental geography). It is significant to note
(meteorology and climatology); the science of seas
that the atmosphere is very important and critical
and oceans (oceanography); the science of solid
component of the living earth system because it,
earth (geology); the science of soils (pedology);
together with the lithospheric and hydrospheric
the science of landforms (geomorphology); the
science of plants and animals (life sciences— components, makes the earth a suitable habitat/
biogeography) etc. but presently physical geog­ place for numerous species of flora and fauna.
raphy is not only the agglomeration and unifi­ Needless to say that climatology is the study of
cation of earth sciences as referred to above but various elements and aspects of atmosphere.
it also studies the patterns of interactions between
1.2. CLIMATOLOGY : AN ATMOSPHERIC
technologically advanced man and physical en­
SCIENCE
vironment including land, air, water, plants and
animals. As a distinct branch' of geography The atmosphere is a complex thick gaseous
physical geography studies the spatial patterns envelope which surrounds the earth from ail sides
and spatial relationships of environmental com­ and is attached to the earth's surface by the
ponents of the globe in regional context, it also gravitational force and it is a significant com-,
studies the causes of regional patterns of such ponent of the biospheric ecosystem because the
spatial relationships, and simultaneously it incor­ life on the earth is due to the existence of this
porates the explanation of spatial and temporal atmosphere otherwise the earth would have become
CLIMATOLOGY
2
2003). In simple words it may be defined as that
barren like moon. Besides providing all necessary
branch of atmospheric sciences which studies the
gases for the existence and survival of life forms
characteristics and behaviour of the atmospheric
in the biosphere, it also filters the incoming solar
conditions based on the study of individual
electromagnetic radiation waves and thus prevents
phenomenon and motions of the atmosphere
the ultraviolet radiation waves reaching the earth's
involving principles of physics.
surface and protects the earth from becoming too
hot. Besides providing energy to earth's biospheric
(3) Climatology
ecosystems, it also plays a key role in the
Climate is defined as the study of aggregate
distribution and redistribution of solar energy both
weather (atmospheric) conditions of any region in
horizontally and vertically on the earth's surface.
long-term perspective. Thus, climatology in­
Itis thus obvious that the detailed study of different
components of the atmosphere has gained cur­ cludes the systematic and regional studies of the
rency. The comprehensive study of the atmosphere atmospheric conditions i.e. weather and climate.
is called atmospheric science which has been Weather refers to the sum total of the atmospheric
conveniently divided into a few significant branches conditions in terms of temperature, pressure,
e.g. aerology, meteorology and climatology. It wind, moisture, cloudiness, precipitation and
has now become imperative to distinguish between visibility of a particular place at any given time.
these three branches, though inseparable, of the Infact, weather denotes short-term variations of
atmospheric sciences. atmospheric conditions and it is highly variable.
Thus, climatology is the study of average
(1) Aerology
atmospheric conditions of a place or region over
Aerology, also called as aeronomy, is in long period of time. According to Trewartha
fact a part of meteorology, as a dictionary meaning ‘climate represents a composite of day to day
reveals that it is considered as a branch of
weather conditions and of atmospheric elements,
meteorology which involves the study of the
within a specified area over a long period of time.’
characteristics of the composition of the atmos­
According to Critchfield ‘climate is more than
phere based on the observations by means of
statistical average; it is the aggregate of the
baloons and aeroplanes whereas aeronomy in­
atmospheric conditions involving heat, moisture,
volves the study of chemical and physical com­
and air movement. Extremes must always be
position of the atmosphere. It may be pointed
considered in any climatic description in addition
out that presently aerology/aeronomy is consid­
to means, trends, and probabilities.’ According to
ered as a part of meteorology wherein we include
Koeppen and De Long, ‘climate is a summary, a
the consideration of the chemistry of different
composite of weather conditions over a long
layers of the atmosphere and physical reactions
period of time, truly portrayed, it includes details
occurring in these vertical layers.
of variations, extremes, frequencies, sequences of
weather elements which occur from year to year,
(2) Meteorology
particularly in temperature and precipitation.
As per dictionary meaning (Webster) Climate is (thus) aggregate of the weather’. G. F.
meteorology is a science which deals with the Taylor has maintained that ‘climate is the integra­
atmosphere and its phenomena, including weather tion of weather, and weather is differentiation of
and climate i.e. the atmospheric conditions and climate. The distinction between weather and
weather of an area. ‘Meteorology is the science climate is, therefore, mainly one of time.’
that deals with motions and phenomena of the Climatology is, thus, defined as ‘that science
atmosphere, with a view to both forecasting which studies the nature of climate, the causes and
weather and explaining the processes involved. interpretation of its spatial variations and its
It deals largely with the status of the atmosphere association with the elements of natural environ­
over a short period and uses the principles of ment and human activities’ (Critchfield). It is now
physics to reach its goals’ (J.E. Oliver and J. J. Hidore, apparent that climatology is that atmospheric
CLIMATOLOGY: BASIC CONCEPTS
science which includes the consideration of
nents of the atmosphere leading to weather and
weather conditions (atmospheric conditions) of a
climatic changes and effects of weather and
place or an area of different spatial scalcs over
climate on man and his activities in particular and
long period of time, of frequent and infrequent
other flora and fauna in general.
weather phenomena as well as average weather
conditions. Climatology becomes both meteoro­ 1.3. CLIMATOLOGY: TYPES AND SUBDIVISIONS
logical (because it studies atmospheric condi­
The science of climatology is divided into
tions) and geographical (because it includes the
various branches on different bases depending on
consideration of weather conditions of a place
the nature of requirement and objectives of the
having certain location on the earth's surfaces e.g.
study of climatic conditions of a definite location
climate of a city like Allahabad, Delhi, London,
e.g. spatio-temporal variations of weather and
New York, etc., of an area e.g. the Ganga plain,
climatic elements, range of spatial units of study
Malabar coast-India, England, Great Plains-USA, i.e. scale consideration, climatic variations and
Red basin-China, of a continent etc.). Following differences etc. H.J. Critchfield identified three
E.T. Stringer it may be forwarded that ‘climatol­ distinct branches of climatology e.g. 1. physical
ogy does not belong entirely within the fields of climatology, 2. regional climatology, and
meteorology or geography. It is a science-really 3. applied climatology.
an applied science-whose methods are strictly
1. Physical Climatology
meteorological but whose aims and results are
geographical’ (quoted in Climatology by Oliver Physical climatology also known as dy­
and Hidore, 2003). namic climatology deals with the interpretation of
Since the emergence of man as an important factors responsible for the spatial and temporal
factor and agent of climate after Industrial variations of exchange of air circulation, heat and
humidity. It studies various elements of weather,
Revolution, which started in 1860 world over, the
namely insolation, temperature, air pressure,
aims and scope of physical geography have
wind, evaporation and humidity, precipitation,
undergone sea change. The technological man and
fogs, visibility etc. Different climates are formed
his economic activities have changed and are
due to combinations of these weather elements.
changing the natural atmospheric conditions
The occurrences of different combinations of
through weather modification schemes (like cloud
these weather elements are accomplished through
seeding and induced artificial precipitation, hail
different processes and mechanisms say dynamic
storm suppression, dissemination and clearance of
processes. Thus, dynamic climatology studies
fogs etc.), urbanization, industrialization, land
these processes of exchange of heat, humidity and
use changes (clearance of forest cover), building
interactions between the atmosphere and the
activities etc. Thus, it has become necessary to
earth's surface. It is, thus, evident that physical
include human interferences in atmospheric con­
climatology studies the factors and processes of
ditions and processes in any meaningful definition
regional variations of climatic conditions. Physi­
of climatology. Simultaneously, the impacts of
cal climatology is, infact, related to meteorology
climate on human health and wealth should also be
wherein atmospheric physics and chemistry and
included in the definition of climatology.
atmospheric dynamics provide basis for general
Thus, climatology may be defined by the
principles of climatology. It may^ be concluded
author as that branch of atmospheric science that physical and dynamic climatology studies the
which includes the study of long-term weather systematic description and analysis of energy
conditions of a place or an area of varying spatial balance of the atmosphere and the earth (i.e.
scales over long period of time, of frequent and global radiation balance or heat budget), atmos­
infrequent weather phenomena, systematic study pheric temperature, humidity and precipitation,
of climate and its distribution on the earth's atmospheric motions and air circulation, air
surface both horizontally and vertically, effects of masses and atmospheric extreme events (atmos­
human economic activities on different compo­ pheric disturbances, droughts, floods etc.).
4 climatoloqv
esses operating over varying ground surfaces
2. Regional Climatology
their impacts on human being, and micro*
Climatic conditions significantly vary from
organisms. This is the reason that a few climatolo*
one region to the other region. In other words,
gists consider microclimate as part of applie<j
there are spatial variations in the combinations of
climatology.
elements of weather and climate (insolation,
(2) Local Climate : The local climate
temperature, air pressure, humidity etc.) and
comprises a few microclimatic areas and hence its
hence different climate types are originated. The
dimension in terms of areal coverage is larger than
regional climatology studies different types of
microclimate. The areal unit of local climate has
climates determined by almost similar climatic
the horizontal extent from 100 meters to 1000
conditions having a set of combination of ele­
meters and vertically, the area extends from
ments of weather and climate in an areal (spatial)
ground surface upto 1000 meters. It may be
unit the size of which varies according to the
mentioned that in the study of local climate of an
spatial scales e.g. from a vegetable garden to crop
area (having different characteristics, namely a
fields, villages, cities, forest cover, desert, moun­
forest cover, an orchard, a village, an urban area
tains, plains, countries and even the continents. It
etc.) the horizontal differences in climatic condi­
is, thus, apparent that the size of areal unit for the
tions are given roore importance than the vertical
study of regional climatology varies from a micro
differences. Local climate varies even in forest
area (e.g. crop field) to macro area (e.g. a
covers depending upon the nature of forest
continent). Thus, the primary goal of regional
canopy, density of trees, ground cover, vertical
climatology is to study the differences in the
climatic conditions of the areal units having structure, seasonality etc.
different spatial scales. Based on spatial scale (3) Mesoclimate : The mesoclimate incor­
M.M. Yoshino identified the following four porates several local climatic areas which has
groups of climates to be included in regional horizontal extent from 100 meters to 20 km and
climatology : 1. microclimate, 2. local climate, 3. vertical extent from the ground surface to 6 km in
mesoclimate, and 4. macroclimate. the atmosphere. It may be mentioned that
(1) Microclimate : The climatic condititoonp ographically the mesoclimatic area is homoge­
of the smallest areal unit having a horizontal neous which is characterized by similar physical
extent from less than one meter to 100 meters and controls of climate e.g. the Ganga Delta, Konkan
vertical extent from the ground surface to 100 coastal plain, middle Ganga plain, Sundarban,
meters (e.g. single crop field or a single household Rewa plateau, Tarai region of Uttar Pradesh,
or the area around a single tree) is termed as Godavari Delta, Sardar Sarovar area etc. may be
microclimate. It may be mentioned that data of cited as examples of typical mesoclimatic areas. It
climatic variables (e.g. temperature, air pressure, may be pointed out that in the beginning spatial
humidity, evaporation, precipitation, air circula­ scales (i.e. scales of area) were used to determine
tion etc.) are not available in published climatological the areas for mesoclimatic studies but recently the
data records and hence such data are always scales of atmospheric motions are given more
obtained through fieldwork (measurement of importance and the study of mesoscale meteoro­
these data by suitable instruments) by the indi­ logical phenomena involving atmospheric mo­
vidual (investigator). It is evident that the microclimate tions like severe atmospheric storms (supercyclones,
is related to weather conditions at ground surface severe tornadoes and hurricanes), pattern of
level and hence the findings of microclimatic precipitation in a physical unit, heat areas,
w a v e
study of different ground surface covers (ranging cold wave areas etc. has gained currency with the
from bare surface to grass covers, crop covers, tree advancement in obtaining meteorological data
covers, human structure covers etc.) may reveal through advanced satellite and radar techniques'
different microclimatic environments which may (4) Macroclimate : Macroclimate ^
enable the investigators to present a generalized known as geoclimate or geographical clim
picture of variation of microclimatological proc- covers largest area of all the other three types
CUMATOWGY : BASIC CONCEPTS 5
regional climate as refred to above. The horizontal that in the beginning the emergence of the concept
distance is more than 20 km, it may be severul
of environmental determinism in the late 19th
hundred kilometers and vertical extent from century gave rise to climatic determinism because
ground surface may be more than 6 km, Thus, the climate being major environmental component of
macroclimatic area may cover even the whole
physical environment was demonstrated as the
continent or a large country like the USA, China, most dominant factor in guiding and controlling
Russia, Brazil, India etc. It may be mentioned that human activities. E. Huntington's ‘Civilization
during the climatic study of microclimatic area and Climate’ (1915) and ‘Season of Birth’ (1938)
which comprises several mesoclimatic areas clearly demonstrate the strong control of climate
averages of atmospheric circulation patterns over on humans. Now the study of relationships
longer period of time are considered to determine between climate and human activities has become
the general characteristics of the study area while more logical and rational because this is based on
smaller scale (in terms of time and space both) careful analysis and interpretation of available
patterns of atmospheric motions (circulation) are data say it is based on quantitative methods.
filtered out (omitted) e.g. for the study of climate
Consequently, now the applied climatology
of India, circulation of heat waves (loo) will be
studies the interactions between climate and
isnored. Similarly, mesoscale motions such as
biosphere i.e. how does climate influence and
mountain and valley winds, land and sea breezes,
control plants, animals including man and in turn
local cold or warm winds would not be considered
how does man modify climate by introducing
in the study of general characteristics of macroclimatic
advertent and inadvertent changes in the physical
area. environment and by making certain weather
Based on the approach of analysis of macro­ modifications e.g. cloud seeding and induced
climates, climatology is divided into (i) descrip­ precipitation. Further, applied climatology in­
tive climatology, and (ii) synoptic climatology. cludes the study of variability of climate, climatic
Descriptive climatology of macroclimatic area changes, air pollution, climate and comfort,
includes the study of the climatic characteristics of climate and heath, climate and society, climate
the ground surface, namely temperature, air pres­ and recreation, climate and archietecture, extreme
sure, humidity, precipitation etc. Synopic climatol­ weather events (e.g. supercyclones, tornadoes and
ogy includes the analysis of dominant patterns of hurricanes, floods and droughts) and their im­
atmospheric circulation. pacts, climate and agriculture, climate and manu­
facturing industries, climate and urban planning,
‘This approach (synoptic approach) obtains
weather forecasting, climate and transport and
a synopsis, or condensed view, of the atmosphere
communication, weather modification etc.
at a given time and is referred to as the synoptic
climatology’ (Oliver and Hidore, 2003). Human biometeorology, which studies the
reactions of human bodies to changes in the
It may be mentioned that the descriptive
atmospheric environment, has gained currency
approach of macroclimatic studies involves the
recently. It lays emphasis on to ‘establish how
classification of world climates into certain types
much of the overall biological variability is the
on the basis of surface climatic characteristics and
result of changes in weather, climate and season’
the principles of synoptic climatology e.g. equato­
(J.E. Hobbs, 1980).
rial climate, monsoon climate, Mediterranean
climate etc. The study of applied climatology is also
divided into three categories based on influences
3. Applied Climatology of climatic environment on human health and
behaviouron different spatial scalese.g. microclimate,
Applied climatology studies the climatic
ecoclimate, and geoclimate. According to M.
controls of human activities and the application of
Bates (1966) three levels of climatic environment
climatic principles and knowledge to solve vari­
affect human behaviour: (1) microclimate, which
ous problems faced by human society e.g. global
represents weather conditions surrounding an
warming and climate change. It may be mentioned
6
CLIMATOLOGY
individual organism; (2) ecological climate or
(atmospheric energy balance), temperature, air
ecoclimate, which represents weather elements of
pressure, atmospheric circulation, humidity and
the habitats of the organisms, in the case of man precipitation and characteristic features of differ­
the habitat may be his house and working places ent climate types but should also be widened so as
like factory, office, mine, agricultural farms, to include its applied aspect (e.g. applied climatol­
pasture etc.; and (3) geographical climate or ogy) including the explanation of relationships
geodimate, which represents weather conditions between climate and human activities and proc­
of larger areal unit and longer temporal span. esses and causes of such relationships at varying
spatial scales e.g. micro, meso and macro levels.
Satellite Climatology
The climatologists' aims should also focus to
The satellite climatology deals with climatic identify relationships between climatic regions
data obtained through satellites which view the and biomes comprising plant and animal commu­
wider areas from above and provide useful data of nities. Besides, the goal of climatology also
day to day weather conditions. The weather includes the investigation of palaeoclimates and
satellites provide images of the earth and cloud their reconstruction, causes and factors of climatic
covers. It may be mentioned that it is the orbit and changes and effective devices of weather forecast­
sensors of weather satellites which determine the ing.
types and nature of weather data. Generally, two It is pertinent to point out that the contents
types of orbits are used, namely (i) high-altitude (scope) of any discipline largely depend on its
geostationary orbit, and (ii) the low-level polar aims and objectives. The scope covering all the
orbit while sensing instruments are classified into contents of climatology may be described through
two major categories e.g. (i) imaging system, and its major branches i.e. physical and dynamic
(ii) sounding system. The satellite imageries climatology, regional climatology and applied
obtained from both polar orbiting and geosynchronous climatology. As already stated ‘physical climatol­
(geostationary) platforms provide useful informa­ ogy deals largely with energy exchanges and
tion about weather conditions mainly cloud cover. physical processes. Dynamic climatology is more
‘Satellite climatology is becoming increasingly concerned with atmospheric motion and ex­
important as digital archives are growing’ (Oliver changes that lead to and result from that motion’
and Hidore, 2003). This aspect has been further (J.E. Oliver and J.J. Hidore, 2003). Thus, the main
elaborated in the 17th Chapter (weather forecast­ contents of physical and dynamic climatology
ing) of this book. comprise global radiation and energy (heat)
balance, atmospheric temperature (distributional
1.4. AIMS AND SCOPE OF CLIMATOLOGY
patterns-horizontal and vertical, and factors influ­
The primary goal of climatology is to study encing temperature distribution), atmospheric
the identification, demarcation and distribution of moisture (hydrological cycle, absolute, specific
and relative humidity, evaporation, condensation
different types of climates, the mode of origin of
and precipitation), motions in the atmosphere
different types of climate, causes and processes
(causes and distributional patterns of pressure
that lead to climatic variations both horizontally
belts, air circulation), global atmospheric circula­
and vertically in the world, different elements of
tion (horizontal circulation and planetary winds,
weather and climate, the varying combinations ol
meridional circulation, Walker circulation and
which give birth to different climatic types, the
southern oscillation), airmasses and fronts (re­
interactions of weather and climate with human
gional patterns of airmasses, frontogenesis,
society and consequent impacts on human activi­
cyclogenesis-convergent circulation, divergent
ties and human health covering both physiological
circulation-anticyclones), atmospheric extreme
and psychological aspects. It may be pointed out
events (atmospheric disturbances-tropical cy­
that the objectives of climatology should not be
clones, hurricanes and tornadoes, floods and
confined only to the study of description of
droughts) etc.
elements of weather and climate like insolation
: BASIC CONCEPTS
As stated above regional climatology aims at 1.5 CLIMATOLOGY : A HISTORICAL
the study of different types of climates of the PERSPECTIVE
world and hence the subject matter of regional
Like other branches of knowledge the
dimatology comprises the classification of world
discipline of climatology has also its roots in the
climates of macro spatial scale, location and
philosophical ideas and postulates of ancient
distribution and systematic description involving
Greeks, Romans and Egyptians. Infact, Greece,
temperature, air pressure and winds, precipitation
Rome and Egypt, the centers of ancient cultures
and effects of climate on natural vegetation. The
anckcivilization, have been cradles of philosophi­
approaches to the classification of world climates cal and scientific ideas. The present status of
are (i) genetic approach, (ii) empirical approach, climatology is the result of gradual but successive
and (iii) objective approach and thus climatic development of climatological knowledge and
classification falls under three broad categories, concepts developed in different periods by innu­
namely (1) genetic classification, (2) empirical merable thinkers and scientists. Even the word
classification, and (3) numerical classification. The ‘climate’ has its Greek origin as the word consists
schemes of classification of world climates by of two Greek words klima, meaning thereby slope
Koeppen, Thornthwaite and Trewartha fall under or inclinitation of the axis of the earth, and logos,
empirical system of climatic classification. meaning thereby discourse or description. Klima
Genetic system of climatic classification is ‘specifies an earth region at a particular place on
based on either physical determinants or that slope-that is, the location of place in relation
airmass dominance as stated by Oliver and to parallels of latitude’ (Oliver and Hidore, 2003).
Hidore (2003). Regional climatology at macro The historical evolution of the concepts and
level also includes the study of reconstruction of theories together with the development of the
palaeoclimates (past climates) and prediction subject (contents) of climatology may be briefly
(forecast) of future climates, climatic changes outlined as follows :
over geological time and causes of climate Ancient period : A few concepts and ideas
changes. about the weather conditions were advanced by
Applied climatology includes the considera­ Greek and Roman thinkers. The Greeks> tried to
understand the nature of atmosphere and its
tion of the impacts of climate on human activities
influences on human health and culture. The first
and human society and human responses to
written documents on atmosphere appeared in 400
climates, namely physiological and psychological
B.C. when Hippocrates produced ‘Air, Water, and
response. Significant relationships between cli­
Places’ wherein he described the influence of
mate and human activities and society include
climate on health. The first compendium on
climate and health, climate and civilization,
meteorology, entitled Meteorologica was pro­
climate and architecture, climate and urban
duced by Aristotle wherein he discussed different
environment, climate and agriculture, climate and
aspects of weather science i.e. meteorology.
industry, climate and transportation and commu­
Theophrastus described different aspects of winds
nication, climate and tourism and commerce etc.
and presented critical explanation of Aristotle’s
Effects of human activities on atmospheric envi­
ideas on weather science in his book ‘De Ventis* in
ronment resulting into changes in global radiation
300 B.C. The ancient Greek thinkers divided the
balance due to global warming caused by increase
globe into three temperature zones on the basis of
ln the emission of greenhouse gases
latitudes e.g. (i) tropical zone, (ii) temperate zone,
(mainly carbon dioxide and methane) at alarming
and (iii) frigid zone.
rate and ozone depletion also become major
Dark Age : The initiatives taken by ancient
contents of investigation in applied climatology,
Greek and Roman thinkers in the field of atmos­
resently, climatic changes and weather
pheric knowledge and weather conditions could
Recasting have more focussed contents of
not be carried forward for many hundred years, say
8 CLIMATOLOGY
(i) First law :
for nearly 1400 years during which a lull prevailed
in the development of geographical as well as P V = p V = k
0 0 A 1 v I K|
climatological ideas and thoughts, though a few
where
Arab thinkers broke the monotony of academic lull
P0 and P, are pressure at two times
in the 9th and 10th centuries during which some
V0 and V, are volume of gas at two times
sporadic ideas regarding atmosphere and weather
K is constant
were put forth.
The Boyle's first law of gases states that if
Period of renewed interest : The long
pressure increases, the volume of gases decreases
continued academic silence of about 1400 years
whereas decrease in pressure causes increase in
was suddenly broken by the emergence of great
gas volume.
desire of the Europeans to undertake voyages for
(ii) The Boyle's second law of gases denotes
different purposes. The period from 15th to 16th
relationship between air pressure (P) and density
centuries is called Great Age of Discovery and
Exploration because efforts were made to discover of gas (D).
and explore new areas and their characteristic P/D = k (at constant temperature)
features including atmospheric and weather condi­ This means increase in air pressure results
tions. It may be mentioned that the explorers in increase in gas density and vice versa.
reported atmospheric and weather conditions of the
It is evident that Boyle postulated inverse
areas they reached according to their own experi­
relationship between air pressure and gas volume
ences and understandings. Such reports of weather
and direct relationship between air pressure and
and climate of different regions outside Europe
gas density.
‘were quite fanciful; they provided for the basis of
With the availability of measuring (of
misconceptions about parts of the world that
atmospheric variables) instruments France started
prevailed for centuries.’
systematic and regular measurement and observa­
Period of scientific analysis : It may be tions of weather phenomena in 1664 with its
pointed out that the knowledge about weather and weather station located at Paris. Edmund Hailey
climate upto 16th century was purely descriptive studied planetary winds and presented a map
and non-coherent because this was based on showing trade winds in 1668. Du Crest introduced
qualitively observed data and description by the centigrade scale for temperature in 1641. Hadley
non-professional individuals. The science of proposed the cell model of tropical circulation
climatology blossomed in the 17th century when a between the tropics of Cancer and Capricorn in
few instruments were invented to measure cli­ 1735 which is widely known as Hadley cell.
matic variables. The proper recording of tempera­
Period of regional description : The period
ture started with the invention of thermometer by ranging from 18th to 19th centuries was character­
Galileo in 1593 and by Santorre in 1612. The ized by the study of weather phenomena at
measurement of atmospheric air pressure became regional and global levels and efforts were made
possible with the invention of barometer by to prepare maps of the countries, continents and
Torricelli in 1643. Thus, the availability of data on the globe depicting climatic variables like, insolation,
temperature and air pressure provided basis for temperature, air pressure and winds, atmospheric
formulation of a few laws about atmospheric disturbances, precipitation etc. on the basis of
conditions, namely Francis Bacon's treatise on extensive data measured by improved and stand­
wind in 1662; Boyle’s laws about air pressure and ardized weather instruments. Recording of cli­
matic data mainly surface temperature and pre­
atmospheric gases etc. Boyle presented a series of
cipitation on regular basis in many of the
laws regarding relationships among air pressure,
European countries and the USA enabled the
volume and density of gases taking temperature as
weather men to store mass dataset for hundreds
constant. His gas laws are stated below :
years. Luke Howard, for the first time, presented *