BharatNotes Insolation
nounUsage in a UPSC answer
Any credible roadmap for India's energy transition must capitalise on the country's abundant insolation, for the high solar radiation across the Thar and the Deccan endows the nation with a comparative advantage that prudent policy can convert into energy security.
Synonyms
Antonyms
Word Family
insolate (v), insolated (adj), solar (adj, cognate), solstice (n, related)
Root
Latin insōlātiō = exposure to the sun; in- = in, upon; sōl = sun
Etymology
From Latin insōlātiō, from insōlāre ("to expose to the sun"), from in- ("in, upon") + sōl ("sun").
Memory Hook
Insolation = "IN comes the SOL (Latin sol = sun)" — the sun's energy coming IN to the Earth. Do not confuse with isolation, which has no 'n' after the 's'.
How This Word Works in UPSC Writing
The incoming solar radiation received per unit area. Four factors govern how much a place gets, and the first dominates: the angle of incidence, since oblique rays spread the same energy over a larger surface and traverse a longer path through the atmosphere, which is why the tropics are hotter than the poles and why this single control underlies almost all of climatology. The others are the duration of daylight, the Earth to Sun distance, and the transparency of the atmosphere. Of the radiation arriving at the top of the atmosphere a large share is reflected or absorbed before reaching the ground, and over the long run incoming shortwave radiation is balanced by outgoing longwave radiation, which is what the heat budget describes. A sustained imbalance in that budget is precisely what global warming consists of.
Don’t Confuse It With
Insolation is the solar energy arriving, albedo the fraction reflected away, and absorption the fraction retained, so the three together account for what reaches a surface. Terrestrial radiation is the longwave energy the Earth emits back to space, and the heat budget is the balance struck between incoming and outgoing. The solar constant is the rate of insolation at the top of the atmosphere at mean Earth to Sun distance, constant only in that averaged sense. Take care not to write isolation, an unrelated word.
Hindi Meaning
सूर्यातप (sūryātap); पार्थिव विकिरण for terrestrial radiation.
Common Questions
- What determines how much insolation a place receives?
- Chiefly the angle at which the sun's rays strike, together with the length of daylight, the Earth to Sun distance and the transparency of the atmosphere.
- What is the heat budget?
- The long-run balance between the shortwave solar radiation the Earth receives and the longwave radiation it emits back to space, which keeps global temperature broadly steady.
Tip: press Alt+S to hear pronunciation
