Question

What factors are responsible for Insolation variation?
A. The angle of inclination of the sun rays
B. The length of the day
C. The transparency of the atmosphere
D. All of these

Answer 1

Hint:Insolation or Incoming Solar Radiation is the energy received by the earth’s surface in the form of short waves. The amount and the intensity of Insolation differ during a day, in a season and in a year.

Complete answer:
As we all know, the primary source of energy for the earth is the “Sun”. Solar Radiation is the energy radiated by the sun in all directions into space in short wavelengths. The earth’s surface obtains only a part of this radiated energy (2 units out of 1,00,00,00,000 units of energy radiated by the sun). Insolation or Incoming Solar Radiation is the energy received by the earth’s surface in the form of short waves. The amount and the intensity of Insolation differ during a day, in a season and in a year.

Option (A) The angle of inclination of the sun rays:- It determines the amount of Insolation variation. The angle of inclination of the sun rays depends on the latitude of a place. The higher the latitude the less is the angle they make with the earth’s surface, which results in oblique or slant sun rays.In addition, the sun’s rays with small-angle traverse more of the atmosphere than rays striking at a large angle. The amount of reflection and absorption of heat by the atmosphere is greater when the path of the sun’s rays is longer. Therefore, the intensity of Insolation is less.

Option (B) The length of the day:- Length of the day differs from place to place and season to season. It also determines the amount of Insolation received on the earth’s surface. The longer the duration of the day, higher is the amount of Insolation received and vice-versa.

Option (C) The transparency of the atmosphere:- Cloud cover and its thickness, dust particles, water vapour, etc. are some of the factors determining the transparency of the atmosphere. They reflect, absorb or transmit the incoming solar radiation.Thick cloud inhibits the solar radiation to reach the surface of the earth. When the sun’s rays progress through the atmosphere-water vapour, ozone and other gases absorb much of the near-infrared radiation (mainly in the troposphere).

Hence the correct answer is option D.

Note:The Subtropical deserts receive the maximum Insolation, where the cloudiness is the least while the Equator receives comparatively less Insolation.
At the same latitude, generally, the Insolation over the continent is more than over the oceans.
In summer, the middle and higher latitudes receive more radiation than in winter.