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Geography FROM 3

Chapter 3 ROTATION AND REVOLUTION OF THE EARTH

ROTATION OF THE EARTH

Rotation of the earth is the spinning of the earth on its axis from W to E. The earth moves in a clockwise direction once every 24hs. That is it takes one full day for the earth to turn from the International Date Line and back to it. The earth rotates once through 360° in 24 hours, 180° in 12 hours, 15° in 1hour and 1° in 4 minutes.

Effects of the Earth’s Rotation

Rotation of the earth causes

  1. Day and night
  2. Deflection of winds and ocean currents
  3. The rising and falling of tides
  4. Difference in time
  • Day and Night

As the earth rotates from W to E, places in the east experiences daylight before places in the west. This is because places in the east are under sunlight, while places in the west are away from the sun when rotation starts.

  • Deflection of Wind and Ocean Tides

Rotation of the earth causes winds and ocean currents to be deflected. They are deflected to the right in the Northern Hemisphere and to the left in the Southern Hemisphere.

  • The Rising and Falling of Tides

Tide is the rising and falling of sea level during the day. It is caused by the earth’s rotation. During rotation, the sun and the moon attract some parts of the earth due to gravitational force. Where the force of gravity is much, the ocean bulges along the coast causing high tides. Where the force of gravity is less low tides are produced.

  • Differences in Time

The earth takes 24 hours to complete a rotation of 360°, and 1 hour to turn 15°. Longitudes which are 15° apart will therefore take 1 hour difference in time. The time in the east is always ahead of the time in the west. This is because, places in the east experience sunlight before those in the west.

Example; during the 2014 world cup competition in Brazil football matches were been played there during the day, but they were watched at the same time, on Cameroon television in the evening.

par Claude Foumtum