Lec 3 Rotation and Revolution of Earth(Additional Material).ppt

1. Class: ADP II Semester QAU Islamabad
Syed Abbas Hyder Shah
Lecturer in Geography
IMCG, Humak, Model Town Islamabad

2. Rotation & Revolution of Earth

3.  The earth undergoes one complete rotation along
its axis in 24 hours.
 For one complete rotation, the earth passes
through 360 degrees of longitude.
 For every one-hour time, a point on the earth
moves through 15 degrees of longitude (360/24
hours = 15o
).
 For every 4 minutes, a point on the earth passes
through 1 degree of longitude

4.  The earth rotates in an anti-clockwise direction
(From West to East).
 Places on the East side of a given point on the earth
are ahead of time while those to the West side of
the same point always lag behind in time.
 The most important result of the earth's rotation is the
daily pattern of DAYS and NIGHTS

7.  In 1878, Canadian Sir Sanford Fleming suggested a
system of worldwide time zones.
 Fleming proposed that the globe be divided into 24
time zones, each 15 degrees of longitude in width.
 Railroad companies in Canada and the United States
began using Fleming's time zones in 1883.
 In 1884, an International Prime Meridian Conference in
Washington D.C. accepted it.

8. Pakistan Time Line/Longitude
750
East, passing from
Shakargarh Sialkot

9.  Each new calendar day begins at midnight on the
International Date Line (Longitude 180o
).
 Crossing the date line causes adjustments to clocks &
dates.
 Traveling from West toward East (Hawaii to Japan)
one jumps into a new day on crossing the Date line.
 From East towards West (Japan to Hawaii), one
looses a day after crossing the line

10.  The Imposition of Day/Night rhythm
 The redirection of the flow paths of both air and
water that flows over the earth’s surface.
◦ Flows in the Northern Hemisphere – Right
◦ Flows in the Southern Hemisphere - Left
 Rise and fall in Tidal Waves over the oceans.

11.  The earth revolves around the Sun on its own
ORBIT (oval-shaped path).
 Perihelion: A point on the orbit where the earth
is closest to the sun - January 3rd
 Aphelion: A point where the sun is farthest away
from the SUN - July 4th.
 On its orbit round the sun, the earth moves
through a plane called the PLANE OF THE
ECLIPTIC.

13.  The earth's axis is inclined to the orbit at an angle of
23.50
 Inclination of the earth’s axis during the movement
round the Sun results in the following:
1. different positions of the noon Sun
2. different positions of Sun rise and sun set
3. different length of days & nights in a year
4. different shadow lengths during the seasons

14.  March 21 is Spring Equinox and…
 September 21 is Autumnal Equinox.
 On these days, the noon Sun is points directly on the
equator so…
 ALL PLACES on the earth’s surface receive
approximately 12 hours of daylight and 12 hours of
darkness.

15. 1. Summer
3. Spring
2. Fall (Autumn)
4. Winter

16.  June 21st
(Summer
Solstice)
 Places in the Arctic circle
points directly toward the
sun so the Northern
Hemisphere receive more
sunlight (hence longer days
and shorter nights)
 On this day, places in the
Southern Hemisphere
receive less sunlight (so
shorter days and longer
nights).

17.  In summer the earth’s axis lean toward the sun so the
energy we receive from the sun is more direct
 The sun also remains in the sky for longer periods and
as such the earth’s surface absorbs more solar energy
 The high temperatures produce summer conditions.

18.  December 21st
(Winter
Solstice)
 On this day, the Sun moves
into the Southern
Hemisphere and places
there receive more
sunlight and experience
longer days and shorter
nights.
 The Northern
hemisphere receive less
sunlight (so shorter days
and longer nights).

19.  Because the earth’s axis point to the same direction
toward the North Star, the Northern hemisphere
leans back on the Sun during winter
 The Sun is lower in the sky and its energy is more
widely distributed
 The Sun is also visible for a much shorter time giving
off little energy so temperature goes down producing
winter conditions

20. NORTHERN SUMMER NORTHERN WINTER