Activity 6. 2: Exam-style practice

Suggested time: 8 minutes

1. The length of a day - as based on daylight or the period between sunrise and sunset - varies over the course of a year. While the days tend to be longer than nights in summer, they become shorter than nights in winter. The change in the length of day is gradual, starting from the longest day of the year to the shortest day. Similarly, starting from the shortest day of the year, the length of a day increases gradually until it is the longest day of the next calendar year.
2. The occurrence of the longest or shortest day of the year is attributed to the astronomical event known as ·solstice·, which occurs twice in a calendar year - first when the apparent position of the Sun is at its northernmost limit (Tropic of Cancer/23.5° North). and again, when the apparent position of the Sun is at its southernmost limit (Tropic of Capricorn/23.5° South).
3. This event of astronomy is further categorized into two parts - summer solstice, which is the longest day of the year, and winter solstice, which is the shortest day of the year. When the Sun is at its northernmost limit at 23.5° N, it is referred to as summer solstice, and when it is at its southernmost limit at 23.5°S, it is referred to as winter solstice.
4. On the other hand, when the Sun's apparent position is just above the equator, it is referred to as equinox - which occurs twice a year. This, however, only applies to the northern hemisphere of the Earth.
5. In the southern hemisphere, summer solstice occurs when the Sun is at its southernmost limit at 23.5° South and winter solstice occurs when the Sun is at its northernmost limit at 23.5° North. Owing to the differences in apparent position of the Sun, each of the two hemispheres experiences summer solstice and winter solstice at different times of the year. When the Sun is positioned at the northernmost limit, the northern hemisphere experiences more daylight as compared to the southern hemisphere. Contrary to this, when the Sun is at its southernmost extreme the southern hemisphere experiences more daylight as compared to its northern counterpart. For a resident of the northern hemisphere, the longest day is when the Sun is at the Tropic of Cancer, and the shortest is when it is at the Tropic of Capricorn.
6. If you happen to be a resident of some country in the southern hemisphere, you will experience the longest day when the Sun is at the Tropic of Capricorn and the shortest day when it is at the Tropic of Cancer. Generally, the Sun is at the Tropic of Cancer on 20 or 21 June (sometimes on 19 or 22 June) and at the Tropic of Capricorn on 21 or 22 December (sometimes on 20 or 23 December). Going by these dates, the longest day of the year has to be 20 or 21 June for the northern hemisphere, but 21 or 22 December for the southern hemisphere. Similarly, the shortest day of the year has to be 21 or 22 December for the northern hemisphere, but 20 or 21 June for the southern hemisphere.
7. Interestingly, when the Sun is positioned at the 23.5° North latitude, the region around the North Pole experiences 24 hours of daylight (day) while the region around the South Pole experiences 24 hours of darkness (night) at a stretch. Similarly, when the Sun is positioned at the 23.5° South latitude the North Pole and surrounding areas experience 24 hours darkness while the South Pole and surrounding areas receive 24 hours of daylight.

American National Sleep Foundation

Do the following based on the text above.
Write NO MORE THAN THREE WORDS to complete each sentence.

1. What two natural events mark the start and end of the daylight period of a day?

2. In which season does the longest day of the year occur in the northern hemisphere?

3. What other name is given to the shortest day of the year in the northern hemisphere?

4. How often does equinox occur?

5. Which region experiences darkness over a long period, when the Sun is positioned at 23.5° North latitude?