General Aspects of Geography
Latitude
·
It
is the angular distance of a point on the earth’s surface, measured in degree
from the centre of the earth.
·
It
is parallel to equator which lies midway between the poles. Hence, these lines
are called parallel of latitude.
·
The
most important lines of latitude are the Equator, the tropic of cancer (23
N), the Tropic of Capricorn (23
S), the Arctic Circle (66
)
and the Antarctic Circle (66
S).
·
The
midday sun is exactly overhead at least once a year on all latitude in between
the Tropic of Cancer and the Tropic of Capricorn. This area, therefore receive
the maximum heat and is called the Torrid Zone.
·
The
areas bounded by the Tropic of cancer and the Arctic Circle in the northern
hemisphere, and the Tropic of Capricorn and the Antarctic Circle in the
southern hemisphere have moderate temperature, hence called Temperate Zones.
·
Area
bounded by the Arctic Circle and North Pole, and the Antarctic Circle and South
Pole are called Frigid Zones. These Zones are very cold as the sun does not
rise above the horizon.
Longitude
·
It
is an angular distance measured in degrees along the equator east or west of
the Prime Meridian.
·
Meridians
are a series of semicircle that run from pole to pole passing through the
equator.
·
Prime
Meridian passes through Greenwich near London, where the British Royal
Observatory is located. Its value is
.
·
Longitudes
have one very important function i.e. they determine Local Time in relation to
Greenwich Mean Time (GMT)
·
Local
time is the time reckoned by the noon- sun at a given place.
·
Standard
Time is the Local Time of the Standard Meridian of a country.
·
In
India, the longitude of 82
is treated as the Standard Meridian. The local
Time at Meridian is taken as the standardtime is treated as the Standard
Meridian. The local Time at Meridian is taken as the standard time for the
whole country. It is known as the Indian standard Time (IST)
International Date Line
·
It
is longitude where the date changes by exactly one day when it is crossed.
·
A
traveler crossing the date line from east to west losses a day and while
crossing the date line from west to east he gains day.
·
|
Do
You Know?
1. The midday sun never shines
overhead on any latitude beyond the Tropic of Cancer and the Tropic of
Capricorn.
2.
3. Russia has as many as 11 time
Zones.
4. Both USA and Canada have five
time Zones, viz. the Atlantic, Eastern, Central, Mountain and Pacific Time
Zones.
|
ROTATION OF EARTH
·
Earth
spins continuously on its axis once in about twenty four hours, which is called
rotation.
·
When
the earth rotates on its own axis, only one portion of the earth’s surface
comes into the rays of the sun and experiences darkness.
REVOLUTION OF EARTH
·
The
motion of the earth around the sun completing one revolution in about 365 days
and 6 hours is called revolution of earth.
·
The
axis of the earth is inclined to the plane of earth’s orbit at an angle of 66
giving
rise to different seasons and varying lengths of day & night.
·
The
earth’ revolution round the sun with its axis inclined at 66
to the plane of earth’s orbit changes the
apparent altitude of the midday sun.
·
The
sun is vertically overhead at the equator on 21 March and 21 September and
these two days are termed as equinoxes.
·
On
21 June, the sun is vertically overhead at the Tropic of Cancer (23
).
This is known as summer solstice, when the northern hemisphere will have its
longest day and shortest night.
·
On
22 December, the sun is vertically over head at the Tropic of Capricorn (23
).
This is known as winter solstice when the southern hemisphere will have its
longest day and shortest night.
·
Beyond
the Arctic Circle (66
)
and Antarctic Circle (66
)
darkness lasts for 6 months and daylight is continuous for the remaining half
of the year.
·
Star
nearest to sun is Proxima Centauri.
·
The
view considering the sun as the centre of the solar system was given by
Copernicus, and is also called the heliocentric view.
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