This set of Solar Energy Multiple Choice Questions & Answers (MCQs) focuses on “Extraterrestrial and Terrestrial Radiations”.

a) Intensity of sun at the top of earth’s atmosphere
b) Intensity of sun at the top of its atmosphere
c) Energy of sun at the top of earth’s atmosphere
d) Force of sun on earth

Explanation: Extraterrestrial radiation is the intensity of sun at the top of earth’s atmosphere. The radiation carries energy from sun to the earth. Sun majorly exerts a gravitational force on other celestial bodies of the solar system including earth.

2. Which of the following is used to measure extraterrestrial radiation?
a) Pressure
b) Watts/square meter
c) Joules/square meter
d) Torque

Explanation: Since extraterrestrial radiation is also a radiation, it is measured in Watts/square meter. This unit is used to measure flux or intensity which is essentially energy radiated per unit time per unit area.

a) is constant
b) monotonically decreases
c) varies
d) monotonically increases

Explanation: Extraterrestrial radiation received by earth varies throughout the year. It is neither a constant function nor a monotonically increasing or decreasing function of earth’s distance from the sun.

4. Why does the extraterrestrial radiation received by earth vary throughout the year?
a) Because earth’s orbit is circular
b) Because of radiation losses when travelling through ether
c) Because of radiation losses when travelling through vacuum
d) Because earth’s orbit is elliptic

Explanation: The extraterrestrial radiation received by earth varies throughout the year. This is primarily because of the earth’s elliptical orbit. This results in varying earth-sun distances throughout the year.

5. What is the average extraterrestrial irradiance received by earth (solar constant)?
a) 1361 Watts/square meter
b) 1361 Watts
c) 1250 Watts/square meter
d) 1250 Joules

Explanation: The average extraterrestrial irradiance received by earth (solar constant) is approximately 1361 Watts/square meter. It varies by + 3% throughout the year. Note that irradiance is always measured in Watts/square meter.
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a) Sum of shortwave and long-wave-up-dwelling radiation minus sum of shortwave and long-wave-down-dwelling radiation
b) Sum of shortwave and long-wave-down-dwelling radiation minus sum of shortwave and long-wave-up-dwelling radiation
c) Difference of shortwave and long-wave-up-dwelling radiation plus difference of shortwave and long-wave-down-dwelling radiation
d) Difference of shortwave and long-wave-down-dwelling radiation plus difference of shortwave and long-wave-up-dwelling radiation

Explanation: All-wave radiation is the sum of shortwave and long-wave-down-dwelling radiation minus sum of shortwave and long-wave-up-dwelling radiation. As the name suggests, it is the net radiation received where net is calculated by difference between net incoming and net outgoing radiation.

7. Which of the following blocks the outgoing long-wave radiation?
a) Earth
b) Seas
c) Clouds
d) Airplanes

Explanation: Clouds tend to block the outgoing long-wave radiation. This results in lower flux of long-wave radiation being emitted into the atmosphere. Earth emits the long-wave radiation. Even if airplanes block or reflect the outgoing long-wave radiation, the amount is negligible.

8. How do clouds block the outgoing long-wave radiation (OLR)?
a) By emission
d) By scattering and absorption

Explanation: Clouds block the outgoing long-wave radiation by scattering and absorption. They absorb the incident OLR and scatter them thereby resulting in reflection of the radiation back to earth.

9. What is albedo?
a) Measure of diffused reflection of solar radiation out of the total amount received by astronomical body
b) Measure of absorption of solar radiation out of the total amount received by astronomical body
c) Measure of diffused reflection of solar radiation out of the total amount received
d) Measure of absorbed of solar radiation out of the total amount received by

Explanation: Albedo is the measure of diffused reflection of solar radiation out of the total amount of solar radiation received by an astronomical body. Due to reflection, the amount of outgoing long-wave radiation from earth is affected.

10. Higher the cloud albedo ________
a) less is the amount of solar radiation reflected back to earth
b) more is the amount of solar radiation reflected back to earth

Explanation: Higher the cloud albedo, more is the amount of solar radiation reflected back to earth. Cloud albedo is a measure of the amount of outgoing solar radiation reflected back to earth. It has nothing to do with the incoming solar radiation received from sun.

11. Which of the following gases absorb outgoing long-wave radiation?
a) Carbon
b) Natural gas
c) Water vapour
d) Argon

Explanation: Water vapour, carbon dioxide and ozone absorb the outgoing long-wave radiation. Carbon is not a gas. Natural gas and Argon do not absorb the outgoing long-wave radiation.

12. Greenhouse gases ________ outgoing long-wave radiation.
a) emit
b) transmit
c) are conducive for
d) hinder

Explanation: Greenhouse gases hinder outgoing long-wave radiation. They absorb some wavelengths thereby preventing thermal radiation from reaching space and adding heat back to the atmosphere (and earth).

13. If not all, most of the outgoing long-wave radiation is emitted to space ________
a) in the absence of greenhouse gases and cloud cover
b) in the presence of greenhouse gases but absence of cloud cover
c) in the absence of greenhouse gases but presence of cloud cover
d) in the presence of greenhouse gases and cloud cover

Explanation: If not all, most of the outgoing long-wave radiation (OLR) is emitted to space in the absence of greenhouse gases and cloud cover. Absence of both, prevents absorption and reflection of OLR back to earth.

14. Presence of greenhouse gases leads to global warming.
a) True
b) False

Explanation: Presence of greenhouse gases leads to global warming. This is because they absorb some wavelengths of the outgoing long-wave radiation and re-emit them back into the earth. This increases the net amount of heat in the planet.

a) True
b) False

Explanation: Outgoing long-wave radiation depends on the temperature of radiating body. It is also affected by earth’s skin temperature, cloud cover and water vapour profile.

Sanfoundry Global Education & Learning Series – Solar Energy.

To practice all areas of Solar Energy, here is complete set of 1000+ Multiple Choice Questions and Answers.