Question

When both incoming and outgoing radiation is balanced, it is called _____.
A) Heat summation
B) Heat balance
C) Heat budget
D) None of these

Answer 1

Hint: It is a special condition of the heat budget. Its disbalance causes changes in the overall temperature of the entire planet. Man-made activities like the emission of greenhouse gases can cause such a disbalance.

Complete answer:
The sun, as we know, is the ultimate source of energy for our planet. It is the radiation from the sun that enables life to sustain itself on earth. This incoming radiation of the sun is known as insolation.
Option A) Heat summation – it is a term used in viticulture and chemistry. In viticulture, it is the amount of heat required for the vines to grow above 10°C during the growing season. In chemistry, it refers to the universal fact that heat absorbed or evolved during a chemical reaction is always fixed for that particular reaction. Neither of these explanations fit in the blank given in the question. Therefore, this option is incorrect.
Option B) Heat balance – this refers to the condition when the incoming radiation from the sun and the outgoing radiation (as the result of reflection) from the earth are perfectly balanced. When this balance is disturbed, the planet either gets warmer or cooler. Thus, this is the correct answer.
Option C) Heat budget – this refers to the relation between the incoming radiation from the sun and the outgoing radiation (as the result of reflection) from the earth. It also accounts for the movement of heat energy in different forms through different systems in our biosphere. Thus, this is the incorrect answer.
Option D) None of these – This option is incorrect as we have already established that option (B) heat budget is the correct answer.

Therefore, the correct answer is Option (B) When both incoming and outgoing radiation is balanced, it is called heat balance.

Note: Insolation, or the incoming solar radiation is affected by the following factors. They are;
- Rotation and inclination of the earth on its axis
- The incident angle at which the rays enter the earth’s atmosphere
- Length of the day
- The density of the atmosphere
All these factors in turn determine the heat budget and the heat balance.