(a) (i) With the aid of a diagram, identify the main lines of latitude. (ii) Calculate the distance between Addis Ababa in Ethiopia (latitude 10°N) and Mase...

(a) (i) Main lines of latitude

Lines of latitude are imaginary parallel circles drawn round the Earth and measured north or south of the Equator.

The main lines of latitude are:

• Arctic Circle, \(66\tfrac{1}{2}^{\circ}\text{N}\)
• Tropic of Cancer, \(23\tfrac{1}{2}^{\circ}\text{N}\)
• Equator, \(0^{\circ}\)
• Tropic of Capricorn, \(23\tfrac{1}{2}^{\circ}\text{S}\)
• Antarctic Circle, \(66\tfrac{1}{2}^{\circ}\text{S}\)

(a) (ii) Distance between Addis Ababa and Maseru

Latitude of Addis Ababa = \(10^{\circ}\text{N}\)

Latitude of Maseru = \(30^{\circ}\text{S}\)

Since the two towns are on opposite sides of the Equator:

\[\text{Difference in latitude}=10^{\circ}+30^{\circ}=40^{\circ}\]

\[1^{\circ}\text{ of latitude}=111\text{ km}\]

\[\text{Distance}=40\times111=4,440\text{ km}\]

Therefore, the distance between Addis Ababa and Maseru is \(4,440\text{ km}\).

(b) (i) Revolution of the Earth

Revolution is the movement of the Earth round the Sun in its orbit. The Earth completes one revolution in about \(365\tfrac{1}{4}\) days.

(b) (ii) Effects of revolution on the length of day and night in the Northern Hemisphere

• The Earth’s axis is tilted, and it remains inclined in the same direction as the Earth revolves round the Sun. Consequently, the length of day and night changes during the year.
• About 21 June, the Northern Hemisphere is tilted towards the Sun. It experiences summer, with longer days and shorter nights. At the Arctic Circle there is 24 hours of daylight, and areas north of it experience the midnight sun.
• About 22 December, the Northern Hemisphere is tilted away from the Sun. It experiences winter, with shorter days and longer nights. At the Arctic Circle there is 24 hours of darkness, while areas farther north may not see the Sun.
• About 21 March and 23 September, the Sun is overhead at the Equator. These are equinoxes, when day and night are approximately equal, each lasting 12 hours.