Here Are The 4 Branches of Physical Geography You Need To Know

Geomorphology, Oceanography, Climatology and Biogeography.

The discipline of physical geography has evolved through successive stages of its development in terms of methodology and approaches to study. 

After taking its birth in the philosophical ideas and reports of ancient thinkers, philosophers and historians of the ancient seats of civilization and culture e.g., Greece, Rome and Egypt, the science of physical environment attained its present status in which different components were added from time to time. 

Previously, physical geography concerned with only three components namely; Lithosphere, Hydrosphere and Atmosphere. But Biosphere has been recently added to this discipline. 

It is desirable that the historical development of four distinct branches of physical geography e.g., Geomorphology, Oceanography, Climatology and Bio- geography should be discussed separately dealing with lithosphere, hydrosphere, atmosphere and biosphere respectively.

Geomorphology:

Geomorphology is a significant branch of physical geography. 

The term geomorphology stems from three Greek words i.e., ge (meaning earth), morphe (meaning form) and logos (meaning discourse). 

‘Geomophology may be defined as the scientific study of surface features of the earth’s surface involving interpretative description of landforms, their origin and development and nature and mechanism of geomorphological processes which evolve the landforms’.

Oceanography:

About three-fourth of the globe (70.8 per cent) is covered by hydrosphere. 

Out of the total surface area of the globe (509,950,000 km ) lithosphere and hydro sphere cover 361,060,000 km and 148,890,000 km respectively. 

The study of hydrosphere (oceans and seas) is called oceanography which includes the con sideration of description and analysis of physical and biological aspects of hydrosphere. 

According to J. Proudman, fundamental principles of dynamics and thermodynamics are also studied in relation to characteristics of ocean water and biological aspects. 

The science of oceans, i.e oceanography, includes marine geology, marine geomorphology, physical oceanography, chemistry of ocean water and bio-oceanography. 

The origin of ocean basins (continental drift and seafloor spreading), structure of crust and mantle, characteristics of ocean deposits and, characteristics and origin of marine landforms are studied in marine geology and geomorphology. 

Physical oceanography includes the consideration of physical properties of ocean water (e.g., temperature, pressure, salinity, density, compressibility, viscosity, water masses and their distributional patterns) and dynamics of ocean water (e.g. sea waves, currents, tides, tsunamis etc.). 

Recently, marine meteorology is also included in oceanography in which atmospheric conditions over ocean water are studied. 

Bio-oceanography includes the study of the characteristics, evolution, distribution and dispersal of marine organisms. 

The study of seas and oceans dates back to the ancient period of before Christ, though early descriptions were based on empirical observations of individuals.

Climatology:

The gaseous envelop surrounding the earth is called atmosphere while the science dealing with the study of the atmospheric components and characteristics is called meteorology and climatology. 

Climatology includes the systematic and regional studies of the atmospheric conditions i.e., weather and climate. 

Weather refers to the sum total of the atmospheric conditions in terms of temperature, pressure, wind, moisture, cloudiness, precipitation and visibility of a particular place at any given time. 

In fact, weather denotes short term variations of atmospheric conditions and it is highly variable. 

On the other hand, climate is defined as aggregate weather conditions of any region in long term perspective. 

According to Trewartha, "climate represents a composite of day to day weather conditions and of the atmospheric elements within a specified area over a long period of time".

According to Critchfield, "climate is more than a statistical average; it is the aggregate of the atmospheric conditions involving heat, moisture, and air movement. 

Extremes must always be considered in any climatic description in addition to means, trends, and probabilities’. 

According to Koeppen and De Long, "climate is a sum mary, a composite of weather conditions over a long period of time; truly portrayed, it includes details of variations, extremes, frequencies, sequences of the weather elements which occur from year to year, particularly in temperature and precipitation.

Climate is thus, aggregate of the weather’. 

G.F. Taylor has maintained that, "climate is the integration of weather, and weather is the differentiation of climate. 

The distinction between weather and climate is, therefore, mainly one of time.

According to Critchfield, climatology is that science which studies the nature of climate, the causes and interpretation of its spatial variations and its association with the elements of natural environment and human activities.

Biogeography:

Biosphere is a life supporting layer which sur rounds the earth and makes plants and animal life possible without any protective device. 

The organic world or biosphere is that part of the earth which contains living organisms; the biologically inhabited soil, air and water.

According to A.N. and A.H. Strahler (1977), all the living organisms of the earth and the environment to which these organisms interact make up biosphere.

Thus, the biosphere consists of all the living organisms (the biotic component), energy (the energy component) and physical environment (abiotic component) and there are continuous interactions between living organisms and physical environment, and among the living organisms themselves.

The average thickness of biosphere or life supporting layer consisting of land, air, water, soil and rock is about 30 km. 

The upper limit of biosphere is determined by the availability of oxygen, moisture, temperature and air pressure which are necessary for the existence of organisms.

Decrease in oxygen, tem perature, moisture and air pressure with increase in height in the atmosphere limits the upper boundary of the biosphere. 

Though the NASA has discovered the presence of bacteria upto the height of 15 km in the atmosphere but the lower layer of the atmosphere upto a few hundred metres accounts for most of the living organisms because favourable environmental conditions are available for the growth and development of living organisms in the lower part of the atmosphere.

The depth of the biosphere over the land is upto the depth of deepest roots of trees or the depth upto which can live the burrowing organisms or the depth at which lie the parent rocks. 

The biosphere extends upto greater depth in the oceans. 

The existence of life has been detected upto a depth of 9,000 m in the deep oceanic trenches and deep sea plains.

The study of biosphere is called biogeography, which includes the consideration of physical environment, soil, animals and plants. 

‘Biogeography as the term indicates, is both a biological and a geographical science. 

Its field of study is the biologically inhabited part of the lithosphere, atmosphere and hydrosphere- or, as it has become known the biosphere’.

Since the living organisms of the biosphere are studied in botany, zoology, biochemistry and geography with different viewpoints and focus, and hence there are variations in the meaning and scope (subject matter of study) of biogeography in the aforesaid disciplines.

If a geographer studies the distribution patterns of plants and animals of the biosphere in spatial and temporal contexts, and attempts to analyse the processes and factors which are responsible for such spatial and temporal variations. 

The biologists limit themselves to the study of physiological, morphological, behavioural and functional aspect of an individual organism.