o Geo+ Graphic- Literally sense that words means description of earth.
o Greeks are supposed to be first geographers.
o Eratosthenes invent the word Geography defined as study of earth as nature of man.
o Geography is governed by a method rather than by specific body of Knowledge and this method is spatial analysis.
o Geo-political refers to the Geographical causation of 1st National Policies.
o Special analysis provides an additional tools of answer writing.
Size of Earth
Shape of earth.
o To attempt to determine earth size and shape by surveys and mathematical calculation.
o Model: The term model means a simplified version of complex reality, a Globe is a model of earth
Earth Geode Shape: In 1687, sir Isaac Newton postulated that the Round earth alongwith other plants could not be perfectly spherical. Until this time the spherical perfection model was a basic model of Geodesy
o Newton reasoned the earth, the earth is slightly miss-shapen by its spinning making a bulged through equator and flattened at the poles. (Oblate spheroid).
o Could the earth is considered as Geode means that the shape of the earth is uniquely earth shaped.
a) Slightly flattened polar diameter approximately 12,700 Kms
b) Slightly budging equatorial diameter approximately 12,756 Kms.
For most practical purposes earth may be properly considered as a sphere. Indeed, it is a more nearly perfect sphere then most of these Sphere with which we come into frequent contact such as Football & Basketball.
Latitude & Longitude
o Fundamental to Geographic Analysis is development of a comprehensive
and logical framework to establish accurate location of any support on the Earth Surface.
o The imaginary Grid System is anchored by the Position of the pole and the equator which are determined by the earth slide variant from a perfectly spherical shape.
o Latitude:- It is the angular distance major North-South Equator we can project a Line From a Given point on the earth Surface P. To the Center of Earth C. The angle between
this line PC and the equatorial plane CA is the major of Latitude of the given point P. Latitude varies from 0o to 90 North and South. Parallel is a line connecting all place of same latitude at 0o Parallel is called Equator. Parallel is called so because All Line of latitude are parallel to each other.
o Longitude:- It is a angular distance between the meridian passing through a given point P and the Greenwich Meridian. It is measure East or West the Greenwich Meridian. Longitude varies from 0 to 1800 East or West.
o Meridian:- It is a line connecting all planes of same longitude. The meridian was used by Roman to refer to the 12 Noon moment/local time that is moment of the day when the Sun is highest in the sky.
o Insolation: – Stands for Incoming Solar Radiation.
As earth revolved around the sun i.e. 1 Year Time. The sun appears to move between the two tropics.
The two tropics represent the farthest limits of this vertical rays of the sun.
o Solstice of Sun: In Latin it refers to Sun reaching the highest position in Northern & Southern Hemisphere.
o Equinox:- Refers to the two days of the years when Sun appears to be over headed the equatorial and all place of the earth home equal day or night.
o Tropic:- The word came from Latin word Tropicane which means the ‘Turn”. It refers to the parallel from where sun appears to turn. The parallel shown in this disappear help us understanding the distribution of insolation on earth surface over the different season/month of a year.
Front:- It is a zone of transition formed in a middle latitude between two air contracted air masses. The cold dried air mass and worm moist of tropical masses. Front often leads to the formation of temperate cyclone. These temperate Cyclones are major reason for high variability of weather condition in middle latitude.
Great Circle:- Any plane i.e. passes center of sphere bisects that sphere and creates a great circle where it intersects the surface of the sphere. (A great circle is a larger)
Shortest Route: Arch of the great circle joining any two point of the earth circle is always a shortest route
between the point.
Each median make a Semi Circle.
Circle of illumination:- Sun illuminates one of the earth at any given moment. This sunlight hemisphere called the circle of illumination is a great circle, that divides the earth into light half and dark half.