ICSE CLASS 9 GEOGRAPHY_ GEOGRAPHY OF VOYAGE SOLUTION

Rotation and Revolution 

Short Answer Questions.

Question 1.What is meant by the earth’s axis ?

Answer: The earth’s axis is the imaginary line joining the North Pole to South Pole, around which the earth rotates.

Question 2. Name the two chief motions of the earth.

Answer: Two chief motions of the earth are rotation and revolution.

Question 3.Describe two characteristics of rotation.

Answer:Two characteristics of rotation are the complete rotation of the earth from west to east in 24 hours and along its tilted axis which is always in the same direction towards the Pole Star.

Question 4. Mention two effects of the rotation of the earth.

Answer:Day and night are caused by the rotation and the creation of centrifugal force resulting in a bulge in the equatorial part and flattened top at the poles.

Question 5.Mention any two possible consequences if the axis of the earth was vertical instead of inclined.

Answer:1. Then at all places on the earth, lengths of day and night would have been equal, i.e. 12 hr of day and 12 hr of night

2. There would have been no seasons.

Question 6.State one reason why we do not feel the motions of the earth.

Answer:According to the gravitational force every thing is attached to the earth, keeping everything at rest at their original position, unless any external force compels to motivate it.

Question 7. Define ‘revolution’.

Answer: Revolution is the revolving of the earth on its orbit around the sun in 365 days and 6 hours nearly.

Question 8. State two chief characteristics of the revolution of the earth.

Answer: The earth revolves at an average speed of 100,000 km per hour. The earth revolves in an elliptical orbit with two particular positions i.e. perihelion 147.3 million km away from sun in January and aphelion 152 million km away from sun in July.

Question 9. Mention two effects of revolution.

Answer: Two main effects of revolution are the seasonal changes throughout the year and the creation of particular heat zones on temperature zones.

Question 10. What is meant by Summer Solstice ? When do we have Summer Solstice in theNorthern Hemisphere ?

Answer:Summer Solstice occurs on June 21, in the Northern Hemisphere, when the sun isoverhead at the Tropic of Cancer and the North Pole is tilted towards the sun, so thesummer season is experienced in the Northern Hemisphere.

Question 11.What is meant by Equinox ? Give the dates of the two Equinoxes.

Answer:Equinox means the time when the days and nights are equal all over the world. The particular dates of equinoxes are 21st March (Spring or Vernal Equinox) and 23rd September (Autumnal Equinox).

Question 12. What will be the duration of daylight in the Northern Hemisphere on March 21st at 23°30′ latitude ?

Answer: The duration of daylight will be of 12 hours.

Question 13. What is the relationship of seasons between the Northern and Southern Hemispheres ?

Answer: The seasonal episodes are reciprocal with each other i.e. if Northern Hemisphere  experiences summer season, then Southern Hemisphere has winter season; in the same way if . there is spring season in Northern Hemisphere, there is autumn season in Southern Hemisphere and vice-versa.

Question 14. How has the phenomenon of the ‘Midnight Sun’ come about ?

Answer:Beyond the Arctic Circle, the regions experience 24 hours daylight in summer seasondue to the North Pole facing continuously towards the pole. It is called the ‘Midnight Sun’. Norway is called land of Midnight Sun.

Question 15.What are the seasons in the Northern and the Southern Hemispheres on 23rd September ?

Answer: There are Autumn season and spring season in the Northern and Southern

Hemispheres on 23rd September, respectively.

Question 16. Mention one effect of seasons in low and high latitudes.

Answer:

The effect of seasons in low and high latitudes is distinct through various phases of

different seasons. Low latitude areas get ample temperature and rainfall while the high latitude areas are cold and receive less rainfall. Tropical regions are always warm with heavy rainfall season, while the temperate and polar regions are cold with scanty rainfall, while the polar regions are always covered with perpetual snow due to the temperature below 0°C. 

Give reasons for each of the following

Question 1. We always see the sun rising in the East.

Answer: As the earth moves from West to East, the eastern part gets lighted first and we see the sunrise in the East.

Question 2. Norway is called the Land of the Midnight Sun.

Answer: Northern part of Norway is beyond the Arctic Circle where the sunlight remains for she months from March to September, so it is called the Land of Midnight sun due to the sunlight seen at night, too.

Question 3. The speed of the rotation of the earth is greater at the Equator than at the Arctic Circle.

Answer: As every part of the earth takes a frill round within 24 hours, the equator being the largest circle of latitude 0°, the speed is greatest at the equator due to crossing the maximum distance per hour. i.e. it is 1660 km per hour, while it decreases to 0° at poles.

Question 4. 25 th of December in New Zealand may be one of the hottest days of the year.

Answer: The sun’s rays are vertical over the Tropic of Capricorn, so . 25th December may be one of hottest days in NewZealand, being situated in the Southern Hemisphere.

Question 5. The length of day and night is not equal at all places on the earth.

Answer: Due to the tilted axis of the’earth and the migration belt of the sun between Tropics of Cancer and. Capricorn, the length of day and night differ from place to place and region to region.

Question 6. The period of twilight and dawn increases polewards.

Answer: On account of the oblique path of the sun towards poles than the vertical path along the equator, the length of dawn and twilight is greater, as it is nearly one hour near equator and 50 days at the poles.

Question 7. Noon is hotter than morning.

Answer: Due to the vertical rays of the sun at noon and the slanting rays in the morning, Noon is hotter than morning.

Question 8. Days and nights are equal at all places on earth on March 21.

Answer: The rays of the sun fall vertical on the equator or the middle part of the earth, on March 21, So the distribution of light is equal all over the world resulting the duration of the day and night equal from pole to pole. It is called the Vernal Equinox

Question 9. Vertical rays are hotter than slanting rays.

Answer: Vertical rays are hotter, because these cross shorter distance from the sun to the earth. Consequently the tropical belt is hotter than temperate and polar areas.

Question 10. Though the earth is nearest to sun in winter yet the winter is cool.

Answer: During the Winter Solstice the earth’s Southern pole is facing towards the sun and the Northern Hemisphere experiences winter season and cold inspite of the earth’s nearest position to the sun.

III. Long Answer Questions

Question 1. What is meant by rotation of the earth ? Discuss the effect of the rotation of the earth.

Answer:

(a) Rotation of the earth takes place around the axis of the earth within 24 hours making one complete round.

(b) The rotation causes day and night alternately; the part of the earth facing the sun

experiences day and on the opposite side the dark part experiences night. One night

and one day together make a complete solar day.

Question 2. Describe the two interesting phenomena made by the circle of illumination viz., Solstice  and Equinox.

Answer:

Circle of illumination is the lighted part of the earth by the sun. On June 21, Northern

Hemisphere enjoys the longest day due to the sun’s position overhead at the Tropic of

Cancer. It is called Summer Solstice. On the other hand when the sun is overhead on

the Tropic of Capricorn, the Southern Hemisphere gets the longest day on December

22, which is known as Winter Solstice. The dates of Equinox are 21st March and 23rd

September, when the days and nights are equal all over the world and there are spring

and autumn seasons in Northern Hemisphere and autumn and spring in Southern

Hemisphere respectively.

Question 3. What is the effect of the inclined axis of the earth on day and night ?

Answer:The difference in the duration of days and nights all over the earth is on account of the inclined axis of the earth. There is six months day in North Pole in summer season (from April to September) and six months day in South Pole in winter season (from October to March).

Question 4.

1. On which two days are the days and nights equal all over the world and why ?

What name do you give to these days ?

2. Which is the largest and which is the shortest day in the Northern Hemisphere and

why ?

3. On which dates does the sun shine vertically overhead at

(a) Equator,

(b) Tropic of Cancer.

(c) Tropic of Capricorn ?

Answer:

1. On 21st March and 23rd September the days and flights are equal all over and

world due to the sun’s rays vertical on the equator. The name is Equinox of this

position.

2. The largest day is 21st June and the shortest day is 22nd December in the

Northern Hemisphere.

3. The sun is overhead on :

(a) Equator on 21st March and 23rd September.

(b) Tropic of Cancer on 21st June.

(c) Tropic of Capricorn oh 22nd December.

Question 5. Describe how the duration of sunlight changes from the Equator to the Poles with respect to the angle of incidence.

Answer: As the angle of incidence changes from 0° to 90° from Poles towards the Equator; So the duration of sunlight also changes. Duration of daylight is 12 hours on equator and 24 hours on the North Pole in summer and 24 hours on the South Pole in winter. So the duration of sunlight increases from the Equator to the North Pole and decrease in the winter season and vice-versa in between Equator and South Pole.

Question 6.

With the help of a diagram describe the heat zones.

Answer:

Question 7. Explain with the help of diagram how the tilt of the earth’s axis and the revolution cause

1. seasons.

2. variation in the length of day and night; and

3. changes in the altitude of the midday sun at different times of the year.

Answer:

1. On account of the different positions of the earth with respect to the sun, in its

orbit, various types of seasons are caused. The sun remains vertical on Tropic of

Cancer on 21st June and on Tropic of Capricorn on 22nd December and on

equator on 21st March and 23rd September. Besides this, the Arctic and the

Antarctic Circles, there is the sunlight for six months from March to September

and from September to March respectively. The winter season from December to

March, spring season from March to June, summer from June to September and

Autumn from September to December in the Northern Hemisphere and vice-versa in the Southern Hemisphere. 

2. The length of day decreases from the equator to the Poles. Apart from this the

polar areas experience six month days and six months nights respectively.

3. The belt of sun’s migration lies between the Tropic of Cancer and Capricorn,

consequently the sun remains overhead in this belt, while beyond this belt the sun

never remains vertical at noon and the sun’s track remains slanting with shorter

curved path in other regions. 

Question 8.Describe how seasons are made and reversed between the Northern and Southern Hemispheres.

Answer: Due to the tilted axis of the earth, the Northern Hemisphere gets maximum sunlight from March to September and Southern Hemisphere from September to March. So, the seasons are also reversed e.g. the summer season in Northern Hemisphere correspond by winter in Southern Hemisphere and the spring is exchanged with Autumn season. 

Question 9.

Distinguish between :

1. Rotation and Revolution 

2. Vertical and Slanting Rays.

3. Equinox and Solstice.

4. Twilight and Dawn. 

Answer:

(i) Rotation :

(a) It is the motion of the earth along its axis.

(b) The time taken for rotation is 24 hours.

(c) It causes days and nights. 

Revolution :

(a) It is the motion of the earth on its orbit around the sun.

(b) The time taken for revolution is 365 days. It causes the different types of seasons.

(ii) Vertical Rays :

(a) Vertical Rays of the sun fall within its migration belt.

(b) Migration belts is between Tropics of Cancer and Capricorn.

Slanting Rays. :

(a) Slanting Rays of the sun fall in temperate and Polar regions.

(b) Slanting Rays of the sun fall in 23 1/21° N – 90°N and 23 1/21° s – 90°S regions

(iii) Equinox :

(a) It means the duration of days and nights equal.

(b) 21st March and 23rd September are the dates of Equinox all over the world.

(c) The sun is vertical on the equator.

Solstice :

(a) It is the particular position of the earth during the year.

(b) The dates of summer and Winter Solstices are 21st June and 22nd December.

(c) The sun is vertical on the Tropic of Cancer and Tropic of Capricorn respectively.

(iv) Twilight :

(a) It is the reflection of light of the sun after the sunset.

(b) This light is slightly yellowish in colour.

Dawn :

(a) It is the reflection of light of the sun before the sunrise.

(b) This light is slightly reddish in colour