Question

When the northern hemisphere has summer, the southern hemisphere experiences _____.
A. Summer
B. Winter
C. Autumn
D. Spring

Answer 1

Hint:
> When the northern hemisphere has spring, the southern hemisphere experiences autumn.
> As the duration of day increases in the northern hemisphere, the duration of the day decreases in the southern hemisphere.

Complete answer:
No matter what time of the year it is, the northern and the southern hemisphere will always experience a season opposite to the other. Therefore, if the northern hemisphere has the summer season, then the southern hemisphere will experience the winter season. When we say opposite we also mean that when it is spring season in the northern hemisphere, then it is autumn season in the southern hemisphere.

The main reason for this phenomenon is the tilt of the earth on its axis. With respect to its orbital plane, the earth is tilted at an angle of 23.4 degrees. Since the earth is tilted slightly, one of the hemispheres will always receive more and direct rays from the sun. It means that when the earth is tilted towards the sun, then the northern hemisphere receives direct sun rays which are experienced by us as the summer season. During this time the southern hemisphere experiences the winter season. This phenomenon keeps alternating as the planet revolves around the sun. This summer season lasts for half a year, or rather half a revolution.

In the second half of the revolution, the earth tilts away from the sun, thus exposing the southern hemisphere to the direct sun rays. This is the time when the northern hemisphere is experiencing winter season, the southern hemisphere is enjoying the summers. It is often said, ‘If you want to celebrate Christmas in summer, then go to Australia’. Well, this is because of the phenomenon that is explained above.

Therefore, the correct answer is B

Note:
> The tilt of the earth is also the reason why days are shorter during the winters and longer during the summers.
> This difference is felt mildly at the equator and felt very drastically as we move towards higher latitudes.
> At the poles this effect is so prominent that it remains daytime for half the year and nighttime for the next half of the year.