1. How Seasons Occur - Part 1
Complete textbook exercise solutions, activities, and shadow experiment explanations — Maharashtra State Board (Balbharati).
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Note: Chapter 1 of Geography "How Seasons Occur - Part 1" is primarily an activity-based and observation-based chapter. The textbook provides introductory questions and observation tables rather than a standard exercise section. The solutions below provide the answers and model observations required to complete the chapter activities.
Let's recall
Day and night occur on the earth because of the earth's rotation around its own axis. The part of the earth that faces the sun experiences day, while the part that faces away from the sun experiences night.
The term used to describe the earth's revolution around the sun is its orbital motion or simply revolution.
The earth takes approximately 365 days and 6 hours (one year) to complete one revolution around the sun.
Our country, India, is located entirely in the Northern Hemisphere and the Eastern Hemisphere.
The sun's rays do not fall perpendicular at all places because the earth is spherical in shape and its axis of rotation is tilted at an angle of 23.5 degrees.
Can you tell?
This is a practical observation activity dependent on your local geographical location. Students should fill the table using a local calendar. A sample worked observation for Mumbai around June 21st is given below as a reference:
| Date | Sunrise | Sunset | Duration of Day | Duration of Night | Source |
|---|---|---|---|---|---|
| 21st June | 06:02 AM | 07:19 PM | 13 Hours 17 Mins | 10 Hours 43 Mins | Internet |
Among the records in the table which is the longest day?
Generally, 21st June is the longest day in the Northern Hemisphere.
What difference do you notice in the duration of the nights day by day?
After June 21st, the duration of the daytime slowly begins to decrease, and consequently, the duration of the nights slowly starts increasing day by day.
Guess the reason behind it.
This happens because of the tilt of the earth's axis and its revolution around the sun. After June 21st (the Summer Solstice), the Northern Hemisphere begins to tilt away from the sun as the earth moves along its orbit.
How did you find out the duration of the night?
The duration of the night can be found by subtracting the total duration of the daytime from 24 hours (or by calculating the total time elapsed from sunset to the next morning's sunrise).
Which two dates had days and nights of the same duration?
In a typical calendar year, 21st March (Vernal Equinox) and 23rd September (Autumnal Equinox) have days and nights of equal duration everywhere on the earth.
Do you think such a change occurs everywhere on the earth?
Yes, changes in the duration of daytime and nighttime occur everywhere on the earth except exactly at the Equator, where days and nights remain approximately equal (about 12 hours each) throughout the entire year.
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Try this & Think about it
In the month of September, the days begin to get shorter and the nights get longer in the Northern Hemisphere. Since the sun appears to shift southward during this period, the shadow of the stick falls towards the North.
During the month of September, the duration of the day and night is the same on September 23rd, which is known as the Autumnal Equinox.
A shadow is always cast in the opposite direction of the light source. Therefore, if the position of the shadow on the wall moves towards the North, it indicates that the sun (and the location of sunrise/sunset on the horizon) appears to be shifting towards the South.