Question

2. Answer any 4 of the following questions in about 30-40 words: (23 =12mar
a) What is meant by revolution of the earth? State one effect of it.
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Answer 1

Answer:

effects of Earth’s revolution include the seasons and variation in the length

of days and nights. In addition to revolution, the tilt of Earth’s axis relative

to its plane of the orbit has a profound effect on Earth. At almost any given

time, one hemisphere is tilted toward the sun, as the other is tilted away.

The hemisphere tilted toward the sun receives more direct sunlight and

thus has warmer temperatures and longer days. The hemisphere tilted

away from the sun receives indirect sunlight. That hemisphere has cooler

temperatures and shorter days.

The changes in hours of daylight and in temperature caused by

revolution and tilt lead to the yearly change of seasons at middle latitudes.

If Earth’s axis were perpendicular to its plane of orbit, seasons would not

occur. In addition, every place on the Earth’s surface would experience 12 hours

of daylight and 12 hours of darkness every day. On the other hand, if Earth’s

axis was tilted more than 23.5°, each hemisphere would experience hotter

summers and colder winters.

The first day of summer in the Northern Hemisphere occurs on or

about June 21 each year. This day has the longest daylight period, because

the sun’s path in the sky is longer and higher than at any other time of the

year. The point at which this daily increase stops is the summer solstice

(SOHL-sites). At the summer solstice, the Northern Hemisphere is at its

the maximum tilt toward the sun. Because this tilt is equal to 23.5°, the sun is

straight overhead at locations along the latitude line of 23.5° N. This

latitude line is called the Tropic of Cancer.

On the first day of summer, every point on Earth within 23.5° of the

North Pole experiences 24 hours of daylight. The boundary of this region,

at latitude 66.5° N is the Arctic Circle. On June 21 in the Southern

Hemisphere, every point south of the Antarctic Circle (latitude 66.5° S )

experiences 24 hours of darkness.

Explanation: