Page 120 - SST Class 06

short summer season some very lowly plants 120°W 150°W 180° North Pole
may grow only in the areas away from the polar 150°E
90°W
ice caps. These regions are known for blizzards, 120°E
high velocity winds carrying ice particles with
them. These regions are called the cold deserts
and they occupy areas of the Arctic margins of
90°E
North America and Eurasia and the Antarctic
continent.
60°W

60°E
30°W
0° 30°E
South Pole
Torch-light falling on a straight surface Longitudes
is bright and covers a smaller area
The antimeridian is halfway around the world, at
Fig. (a)
180 degrees. It is the basis for the International
Date Line.

Half of the world, the Eastern Hemisphere, is
Torch-light falling on a slanted surface
is less bright, but covers a bigger area measured in degrees east of the prime meridian.
Fig. (b) The other half, the Western Hemisphere, in
degrees west of the prime meridian.
Observe the given figures carefully. A torch-light is
shown falling on a straight surface Fig. (a) and on Degrees of longitude are divided into 60 minutes.
slanted surface Fig. (b). Answer the questions below: Each minute of longitude can be further divided
1. Which surface covers smaller area in the above into 60 seconds. For example, the longitude of
figures? Paris, France, is 2° 29' E (2 degrees, 29 minutes
2. Why do the above phenomena happen? east). The longitude for Brasilia, Brazil, is 47° 55'
3. Is the slanted surface less bright than the vertical W (47 degrees, 55 minutes west).
surface? Why? Grid
The Parallels and the Meridians or the lines
LONGITUDES
of latitudes and longitudes together form a grid
Longitude is the measurement east or west of the of intersecting lines on the globe or on a map.
prime meridian. Longitude is measured by Whereas the parallels help us to locate a place
imaginary lines that run around the earth verti- north or south of the Equator, the Meridians do
cally (up and down) and meet at the North and the same east or west of the Prime Meridian. The
South Poles. These lines are known as meridians. point of intersection of these lines gives the
Each meridian measure one arc degree of precise location of a place. For example, the
longitude. The distance around the earth mea- exact location of Haridwar in Uttaranchal is at
sures 360 degrees. the point of intersection of 30° N and 78° E
The meridian that runs through Greenwich, (longitude and latitude respectively).
England, is internationally accepted as the line of
0 degrees longitude or prime meridian.

Social Science-6 120