WBBSE Class 6 Geography Chapter 4 Rotation of the Earth Introduction
1. Since the Earth spins in a west-to-east direction, the Sun seems to rise in the east and set in the west every day. This is known as the Sun’s apparent daily motion or movement.
2. The Earth spins on its axis tilted at an angle of 66V20 to the orbital plane in a west-to-east direction. This is known as the rotation of the Earth.
3. The circle that divides the Earth into a lit half and a dark half is called the circle of illumination or shadow circle. The lighted half of the Earth experiences day and the dark half experiences night.
4. The transitional time immediately before sunrise is called dawn and that immediately after sunset and before the evening is called dusk.
5. The Earth pulls everything towards its center. This tension is known as gravity.
Read and Learn More WBBSE Class 6 Geography Notes
6. The International Date Line is an imaginary line that follows the 180° longitude mostly, except in a few places.
7. When the Sun remains overhead on a particular meridian, it is 12 noon at all places on the same meridian. That is why lines of longitudes are known as meridians.
8. The time of a place that is calculated from 12 noon is known as the local time of that place.
9. A meridian that passes through the middle of a country is considered as the standard meridian of that country. And the local time of that meridian is considered the standard time of that country.
10. The local time of 82°30 ‘E meridian has been taken as the Indian Standard Time (1ST).
11. Ante Meridian (am) is the period of time between 12 midnight and noon.
12 Similarly, the time between 12 noon and before 12 midnight is called Post Meridian (pm)