LATITUDES &
LONGITUDES
Mathematical
location of places
on the globe
The Earth’s surface is so vast that unless a
mathematical method can be used, it is
impossible to locate any place on it.
For this reason, imaginary lines have been drawn
on the globe. One set running east and west,
other set runs north and south. The intersection
of these pin-points any place on the earth’s
surface.
LATITUDES
“ANGLE”
Latitude is the angular distance of a
point on the earth’s surface, measured
in degrees from the centre of the
earth.
It is parallel to a line , the equator,
which lied midway between the poles.
These lines are therefore called
parallels of latitude, and on a globe are
actually circles, becoming smaller
polewards
Some Important Latitudes
Equator- 0 degree
North Pole and South Pole- 90 degrees N and S
Tropic Of Cancer- 23.5 degree N
Tropic of Capricorn- 23.5 degree S
Arctic Circle- 66.5 degees N
Antarctic Circle- 66.5 degrees S
*The linear distance between a degree of latitude is
taken to be 69 miles. This figure can be used to
calculate distance of places from the equator
LONGITUDE
“ANGLE”
Longitude is an angular distance
,measured in degrees along the
equator east or west of the Prime
Meridian .
On the globe longitude is shown as a
series of semi-circles that run from
pole to pole passing through the
equator. Such lines are called
meridians.
Prime Meridian
The Prime Meridian is a 0 degree longitude from
which all other meridians radiate eastwards and
westwards upto 180 degrees.
As the parallels of latitude become shorter
polewards, so the meridians of longitude , which
converge at the poles , enclose a narrower space.
The degree of longitude therefore decreases in
length.
They have a very important function, they determine
the local time in relation to GMT or Greenwich Mean
Time, which is referred to as World Time.
LONGITUDE AND TIME
Local Time
Since the earth makes one complete revolution of
360° in one day or 24 hours, it passes through 15° in
one hour or 1° in 4 minutes.
The earth rotates from west to east, so every 15° we
go eastwards, local time is advanced by 1 hour. /
Conversely, if we go westwards, local time is
retarded by 1 hour. We may thus conclude that places
east of Greenwich see the sun earlier and gain time,
whereas places west of Greenwich see the sun later
and lose time.
Example: London(0degree5minuteW) and Madras
(80degree E).
International Date Line
A traveller going eastwards gains time from
Greenwich until he reaches the meridian 180°E. when
he will be 12 hours ahead of G.M.T. Similary in
going westwards, he loses 12 hours when he reaches
180°W. There is thus a total difference of 24 hours
or a whole day between the two sides of the 180
meridian. This is the International Date Line where
the date changes by exactly one day when it is
crossed.
A traveller crossing the date line from east to west
loses a day, and while crossing the dateline from west
to east he gains a day.
Thank you and well done!
@ExplainedbyOjasvi - Ojasvi Sharma
