Part I Chapter
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PART I CHAPTER - I INTRODUCTION CHAPTER I Introduction Climatology is a science that seeks to describe and explain the nature of climate, why it differs from place to place and how it is related to the other elements of natural environment. Climatology involves the collection and interpretation of observed weather data for developing generalization and also for testing theories. It necessitates instrumental and statistical techniques and hence is regarded as a study of causal system based on mathematical structure. The 'geographical climatology1, as the name suggests is the combination of climatology as physical science and geography as the field science with special reference to biotic life in relation to space and time. Climatology in its investigation of spatial relationship makes abundant use of tools of geography and mathematical models. However, these mathematical models, when applied to large area may not explain completely all the observed facts of climate. It is the function of the geographical climatology to describe and interpret the actual facts of climate (Stringer, 1972). The usual method of presenting these facts is in the form of maps or verbal 2 statements or in the form of statistical tables from which the maps or verbal statements are derived. Geographical climatology considers atmosphere as an entity with its movement and momentum as are affected by geographic factors such as latitude, altitude, topography and distribution of land and i/ater. It has been a long felt need for the geographers and the students of climatology in getting coherent information about the spatial and temporal behaviour of climatic elements for the state of Maharashtra. The geographical disposition of Maharashtra in India has a great bearing on the climatological studies of the entire sub-continent. The burst of monsoon over the Konkan coast, is of great significance to the people of Deccan plateau, Central India and over northern India as a whole; rather than the initiation of monsoon arrival, along the Kerala coast. Geographical climatology, as it primarily deals with the regional distribution of climatic elements, has been restricted in this present study to the two distinct geographical units of Maharashtra, the coast (Konkan) and the plateau (Desh). The study of geographical climatology offers a helpful approach In planning the agricultural operations, developing resort centers and for planning and executing various irrigation projects etc. Objectives of the Present study : The primary aim of the study is to map, describe and interpret the various climatic elements in relation to the climate of Maharashtra with a geographical background. Rainfall analysis has been emphasised amongst all the climatic elements. The rainfall data is analysed with an altogether different Astro-climatological approach. Astro- cliiaatology deals with the spatial and temporal distribution of primary and derived climatic element* in correlation with the occurrence of the various astronomical phenomena viz. the a. transit of the sun into the signs of zodiac, solar transits in the various fixed star constellations (Nakshatras) the conduction of the inner planets mercury and Venus with the sun and their setting durations phases of the moon etc. An investigation of the climatic appliances related t water budget, the moisture indices has been stressed in greater length;as these aspects find a very little place in the work done so far, in relation to Maharashtra, In additic some aspects of applied climatology, especially the comfort 4 zones and architectural layout for some stations in Maharashtra have been dealt with. previous work done and the present need s Most of the published work in the subject, namely the distribution of climatic elements, climatic classification based on Koppen and Thornthwaite systems, is related to India as a whole. The climatological investigations with special reference to Maharashtra are rare; mention may, however, be made to a few studies in which some attention has been paid to this theme and region. Prominent amongst these are the papers by Raghavendra and by C.R.V. Raman. Raghavendra has studied the trends and periodicities of rainfall in Maharashtra and applied various fcfcc statistical parameters to rainfall analysis; while C.V. Raman's investigations are related to the dates of commencement of sowing rains in Maharashtra. The publication in the series "State Climatological Summaries"; the "Climate of Maharashtra State" is of formative type and concerns mainly with the facts and information about the climatic elements. A detailed study, on the climatological aspects of Maharashtra with special emphasis to astro- -climatology has been a neglected topic in the existing 5 literature on climatology. Although the statistical information about precipita tion data is available on daily basis over a large number of years at various Taluka places there is comparatively paucity of data on temperature which is available for some district places, and that too for a comparative short period. This has always resulted in confining the climatologlcal studies, especially dealing with climatic classification to district places only. Constraints of similar nature have limited the scope of deliberations related to applied climatology. The computation of daily rainfall data on Naks hatr awls e basis In this study therefore has been restricted primarily at the district level. The present approach of the Nakshatrawise analysis of the,rainfall will, in future, create a new opening for the estimation and evaluation of the minor regional variations in the precipitation characteristics at Taluka level. The basic climatic data used in this work consists of the monthly and yearly rainfall figures for the various district places over a period of 70 years from 1901 to 1970 and the temperature and humidity data available for the limited G number of years during this period. This data was supplied by Indian Meterological Department, Pune; while the old issues of Gazetteer part III from 1948 to 1970,were the main source of the daily rainfall data. Proposed outline of the work : The study of geographical climatology has been organized into three sections x (i) Physical setting (ii) Spatial distribution of various cJ-imatic elements , and (ill) Climates of Maharashtra and some aspects of applied climatology. The first section describes briefly the physical setting, soil types and natural vegetation. The second part on basic climatic elements is mostly devoted to spatial and temporal variations in the distribution of climatic elements. The Chapter three in this section mainly concerns with the distribution of primary climatic elements such as temperature, pressure, relative humidity and cloud amount. These elements in the original and in derived forms are illustrated by graphs and maps. In addition to 7 Isothermal maps for different seasons the hysteresis curves of relative temperature have been dram for various places, in order to bring out the influence of continentallty on the yearly march of the seasons. The average pressure conditions for various seasons and the distribution of relative humidity at 8.30 and 17.30 hours during the four seasons of the year are discussed with the help of maps. Seasonal and diurnal variations in the wind direction influencing the local weather condition are studied \d.th the illustrations from the wind ros e maps. This is followed by the investigations of the main rainfall characteristics and the temporal variations of the dry and wet years during the last 70 ye£.rs. An attempt is also made to examine the drought and excessive rainfall years and to find out the probability of occurrence of droughts in the state. The next chapter of this section has been specially devoted to ITakshatrawise rainfall analysis, in Indian farmer is mostly habituated to plan his agricultural activities with the rainfall incidents in various Hakshutras. The division of a solar yetr into the various Nakshatra periods has a special astronomical connotation and therefore an attempt in search of 8 the Interrelationship between the rainfall amounts and various Nakshatras is made. Rainfall distribution in the fourteen Nakshatras from Kruttika to Vishakha according to the Hindu Calender forms the basis of the present study on the rainfall analysis. This analysis of rainfall data is relevant to 28 parts in all of the fourteen Nakshatras? as a Nakshatra period is further divided each into two parts I and II. Rainfall averages and variability have bean calculated Nskshatrawise and represented by means of naps. A matrix of simple eorrelatlonfl between the 28 input variables Tor each of the 26 district places has been evaluated by using the eomptttorf st 2.I.F.R. Bombay, and Regional Computer Centre, Puna. This matrix has been used to investigate the correlation between the various distinct grou^3 of variables which are significant at different levels of Ji^iiricance. This analysis further concentrates for a search of those BTakshatra groups which will be useful from the point of long range forcasting of rainfall. The third section focust&* on climates of the State and some aspects of Applied Climatology. The chapter six is mainly devoted to climatic classification and it deals with a critical account of the application of the various schemes putforth by Koppan, Lang, de-Mortonne, Miller and Thomthwaite 3 for dassifing the climates. Considering further the importance of heat and moisture factors in eco-climatic studies, an attempt is made to examplify how the Thomthwaite's scheme based on the concept of the potential evapotranspiration meets the full ecological requirements of climatic classification with reference to Maharashtra. Water balance charts for 26 district places have been used to delimit the areas of water surplus and deficit in the State. Deliberations related to 'discomfort indices' are confined to the last chapter in this section. The analysis of discomfort indices, both for morning as well as for evening is made in order to recognize suitability of climates for human comfort. In this very chapter, the architectural layout in relation to the varied climatic conditions for the four selected stations in the state has been studied.