8. How Seasons Occur - Part 2

(1) The apparent movement of the sun means _________.

• (a) The sun revolves around the earth in a year
• ✔ (b) It appears that the sun moves to the north or south in a year.
• (c) The earth keeps on changing its position.

(2) If the axis of the earth were not tilted _________.

• (a) The earth would not have rotated around itself.
• (b) The earth would have revolved around the sun with greater velocity.
• ✔ (c) Different parallels on the earth would have experienced the same climate throughout the year.

(3) 21st June and 22nd December are solstice days, that is, _________.

• ✔ (a) The sun starts its southward journey from Tropic of Cancer on 21st June and northward journey from Tropic of Capricorn on 22nd December.
• (b) The Dakshinayan of the sun takes place between 21st June and 22nd December.
• (c) The Uttarayan of the earth takes place between 21st June and 22nd December.

(4) The revolution of the earth around the Sun and the tilt of the axis of the earth together are responsible for the following seasons.

• (a) Summer, rainy season, Retreat of Monsoon and winter,
• (b) Summer, winter and spring
• ✔ (c) Summer and winter.

(1) What leads to the occurrence of seasons?
The occurrence of seasons is primarily caused by two factors: the revolution of the earth around the sun, and the tilt of the earth's axis of rotation (which is tilted at an angle of 23.5 degrees).

(2) What is the duration of the day on equinox?
On an equinox day (21st March and 23rd September), the duration of daytime and nighttime is equal everywhere on the earth, which means the duration of the day is exactly 12 hours.

(3) Why is the effect of the seasons not experienced in the equatorial region?
The equatorial region does not experience any change of season because it receives almost perpendicular sunrays throughout the year. Consequently, there is hardly any change in the duration of sunlight or the prevailing temperature in this region over the course of the year.

(4) Why is the sun visible for more than 24 hours during Dakshinayan in the region between the Antarctic Circle and the South Pole?
During Dakshinayan, the southern hemisphere is tilted towards the sun. As a result, the region between the Antarctic Circle and the South Pole is continuously exposed to sunlight, meaning the sun does not set and remains visible for 24 hours or longer (up to six months exactly at the South Pole).

(5) Why are penguins not found at the North Pole?
Penguins are naturally adapted to the harsh climatic conditions of the Antarctic region in the southern hemisphere. Due to geographical isolation and their specific habitat requirements, they are exclusively found in the southern hemisphere and not at the North Pole.

(1) The earth's velocity varies according to the period of revolution.
Wrong.
Corrected statement: The earth's velocity varies according to its distance from the sun (it decreases during the aphelion position and increases during the perihelion position).

(2) If we observe from the northern hemisphere, we see the apparent movement of the sun.
Wrong.
Corrected statement: We can see the apparent movement of the sun from any place on the earth, not just the northern hemisphere.

(3) The dates of equinox change every year.
Wrong.
Corrected statement: Generally, the dates of equinox remain the same every year (around 21st March and 23rd September), though they may vary by a day or so.

(4) North Canada experiences summer from September to March.
Wrong.
Corrected statement: North Canada is located in the northern hemisphere, so it experiences winter from September to March.

(5) When it is summer in South Africa, Australia has winter.
Wrong.
Corrected statement: Both South Africa and Australia are located in the southern hemisphere, so they experience the same season (summer) at the same time.

(6) Duration of daytime is less on the vernal and autumnal equinoxes.
Wrong.
Corrected statement: The duration of daytime and nighttime is equal (12 hours each) everywhere on the earth on the vernal and autumnal equinoxes.