How Seasons Occur - Part 2 | Class 7 | Geography | Chapter 8 | Maharashtra State Board
Explore the celestial dance of Earth with our study channel! Uncover the mysteries of the apparent movement of the Sun, the transitions between Dakshinayan and Uttarayan, and the significance of perihelion and aphelion positions in our planet's orbit. Delve into equinox and solstice days, understanding the cyclical nature of seasons and their impact on the living world. Witness the marvel of bird migration, intricately linked to Earth's dynamic climate. Join us on a captivating journey through astronomy, meteorology, and ecology, as we unravel the interconnected web of the cosmos and its influence on life. Enrich your understanding of our planet's rhythms and their profound implications on the diverse ecosystems that thrive within it. Subscribe now for an educational voyage into the heart of Earth's wonders!
Questions & Answers
Q.1. Complete the statements using correct options:
1. The apparent movement of the sun means that ________.
(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.
Ans. (b) it appears that the sun moves to the north or south in a year.
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.
Ans. (c) different parallels on the earth would have experienced the same climate throughout the year.
3. 21sl 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 Capricon 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 22nd December and 21st June.
Ans. (a) the sun starts its southward journey from Tropic of Cancer on 21st June and Northward journey from Tropic of Capricon on 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 ______.
(a) summer, rainy season, retreat of monsoon, winter.
(b) summer, winter and spring.
(c) summer and winter.
Ans. (c) summer and winter.
2. Answer the following questions:
1. What leads to the occurrence of seasons?
Ans. (i) Seasons occur due to the revolution of the earth.
(ii) Seasons also occur due to the tilt of the earth’s axis of rotation.
2. What is the duration of the day on equinox?
Ans. (i) The circle of illumination divides all the parallels from the north pole to the south pole equally.
(ii) Everywhere on the earth, the night time and day time are of equal duration. This condition is called equinox.
(iii) Thus, the duration of the day will be twelve hours on equinox.
3. Why is the effect of the seasons not experienced in the equatorial region?
Ans. (i) Seasons have been decided on the basis of the duration of sunlight, equinoxes & solstices
(ii) The equatorial region receives perpendicular sunray almost throughout the year.(iii) Hence the climate of that region does not change at all in the year.
(iv) Hence the effect of the seasons is not experienced in the equatorial region.
4. Why is the sun visible for more than 24 hours during Dakshinayan in the region between the Antarctic Circle and the South Pole?
Ans. (i) Sunrays are never perpendicular on any of the parallels between Tropic of Cancer & the North pole or between Tropic of Capricorn & the South pole.
(ii) In the period from 23rd September to 21st March (Dakshinayan) the region between Antarctic circle and the south faces the sun. The whole of Antarctic Circle falls within the zone of illumination.
(iii) So the sun is visible in the sky for more than 24 hours.
5. Why are penguins not found at the North Pole?
Ans. (i) The living world on the earth is affected by the cycle of seasons.
(ii) Penguins are native to south pole. Penguins have adapted to the natural conditions prevailing in the Antarctic regions of the south pole.
(iii) Besides predators like polar bears roam within the Arctic Circle. Hence penguins are found at the South pole & not at the North pole.
3. Rewrite the following statements after correcting them:
1. The earth’s velocity varies according to the period of revolution.
Ans. The earth’s velocity varies due to the rotation of the earth.
2. If we observe from the northern hemisphere, we see the apparent movement of the sun.
Ans. We see the apparent movement of the sun from both the northern & southern hemispheres.
3. The dates of equinox change every year.
Ans. The dates of equinox does not change every year. They vary by a day or so.
4. North Canada experiences summer from September to March.
Ans. North Canada experience winter from September to March.
5. When it is summer in South Africa, Australia has winter.
Ans. When it is summer in South Africa, Australia has summer.
6. Duration of daytime is less on the vernal and autumnal equinoxes.
Ans. On the vernal (spring) equinox and autumnal equinox, day and night time are of the same duration.
4. Spot the error in the diagram given below:
Ans.
E X T R A
Q.1. Fill in the blanks.
1. The position of the sun at sunrise, appears to change on the horizon everyday.
2. Seasons occurs only with reference to the northern and the southern hemispheres.
3. The path of the revolution of the earth around the sun is elliptical.
4. As the earth revolves around the sun, its perpendicular rays fall on the equator twice a year.
5. In the northern hemisphere prevails from 21st March to 21st June, while spring, autumn prevails from 23rd September to 22nd December.
6. 21st June is the longest day and has the shortest night in the northern hemisphere.
7. 22nd December marks the longest day and the shortest night in the southern hemisphere.
8. On the equator duration of day and night is the same throughout the year.
9. The occurrence of seasons one after the other leads to the cycle of seasons.
10. Agricultural seasons also depend on the local climatic conditions.
11. Continuous, occurrence of rain in a specific period gives rise to additional season besides summer and winter.
12. On 21st March and 23rd September day time and night time are same all over the earth.
13. The period in which the position of the rising sun keeps moving towards the south is called Dakshinayan.
14. The period in which the position of the rising sun keeps moving towards the north is called Uttarayan.
15. In the northern hemisphere 23rd September is called Autumnal equinox.
2. Complete the following sentence:
1. The movement of the sun towards the north or south in a year is called ________.
Ans. the apparent movement of the sun.
2. Seasons occur only with reference to _______.
Ans. the northern and the southern hemisphere.
3. The diurnal apparent movement of the sun is related to _______.
Ans. the rotation of the earth.
4. The annual apparent movement of the sun is related to ______.
Ans. the revolution of the earth and the tilt of earth’s axis.
5. In the first week of July, the earth is at _______.
Ans. the farthest point from the sun.
6. The circle of illumination1 divides ______.
Ans. all the parallels from the north pole to the south pole equally.
7. In the northern hemisphere, spring prevails ______.
Ans. from 21st March to 21st June.
8. In the northern hemisphere, autumn prevails ______.
Ans. from 23rd September to 22nd December.
9. Only on 21st June and 22nd December, the sun rays become _____.
Ans. perpendicular on the Tropic of Cancer and Tropic of Capricon respectively.
10. Seasons have been decided on the basis of _________.
Ans. the duration of sunlight, equinoxes and solstices.
11. The living world on the earth is affected by ________.
Ans. the cycle of seasons.
12. Continuous occurrence of rain in a specific period gives rise to _____.
Ans. an additional season besides summer and winter.
3. Complete the statements using the correct options:
1. In the course of one year, Arctic tern has to travel in search of food.
(a) around 50,000 km.
(b) around 70,000 km.
(c) around 90,000 km.
Ans. (b) around 70,000 km.
2. Due to severe winter and lack of food, Siberian cranes from the cold northern regions visit India travelling around
(a) 8 to 10 thousand kilometers.
(b) 10 to 12 thousand kilometers.
(c) 12 to 14 thousand kilometers.
Ans. (a) 8 to 10 thousand kilometers.
3. The two Poles experience either sunrise or sunset on
(a) Solstice days.
(b) Equinox days.
(c) Dakshinayan.
Ans. (b) Equinox days.
4. The diurnal apparent movement of the sun is related to
(a) the revolution of the earth.
(b) rotation of the earth.
(c) tilt of the earth’s axis.
Ans. (b) rotation of the earth
4. Answer in one sentence:
1. What is the apparent movement of the sun?
Ans. The movement of the sun towards the north or south in a year is called the apparent movement of the sun.
2. What is Equinox?
Ans. On 21st March and 23rd September, the north pole and the south pole are at the same distance from the earth due to which the daytime & night time are of equal duration everywhere on earth. This is called Equinox.
3. How have seasons been decided?
Ans. Seasons have been decided on the basis of the duration of sunlight, equinoxes and solstices.
4. Name the four seasons of Europe and North America.
Ans. The four seasons in Europe and North America are summer, autumn, winter and spring.
5. Which living creatures are found in the Antarctic region?
Ans. Birds like penguins, fish like seal and animals like walruses are found in the Antarctic region.
6. Which animals are found in the polar region of the northern hemisphere?
Ans. In the polar region of the northern hemisphere animals like reindeer, polar bears, Arctic foxes, etc are found.
7. What are the factors that influence the seasons?
Ans. The changes in the atmosphere, vapour in the air, the wind and the precipitation influence the seasons.
8. What do you mean by Dakshinayan?
Ans. The period in which (from 21st June to 22nd December) the position of the rising sun keeps on moving towards the south is called as Dakshinayan.
9. What is Uttarayan?
Ans. The period in which (from 22nd December to 21st June) the position of the rising sun keeps on moving towards the north is called as Uttarayan.
5. Answer the following questions:
1. What is called perihelion position of the earth?
Ans. As the earth moves in an ellipse, its distance from the sun does not remain the same. It is at its minimum distance in the first week of January. This is called the perihelion position of the earth.
2. What is called aphelion position of the earth.
Ans. In the first week of July, the earth is at the farthest point from the sun. This is called the aphelion position.
3. What is called circle of illumination?
Ans. The illuminated and dark portions of all the parallels including the equator is called circle of illumination. It divides all the parallels from the north pole to the south pole equally.
4. What are Solstice days?
Ans. Solstice days are the days when the earth’s tilt towards the sun is at its maximum.
On 21st June the northern hemisphere is tilted towards the sun and the Tropic of Cancer starts receiving perpendicular rays of the sun. On 22nd December the Southern hemisphere is tilted towards the sun & the Tropic of Capricorn starts receiving perpendicular rays of the sun. These two days are called solstice days.
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