Sublimation

noun (uncountable)

/ˌsʌblɪˈmeɪʃən/

Sublimation is the direct phase transition of a substance from the solid state to the gaseous (vapour) state without passing through an intermediate liquid phase, occurring when the ambient pressure is below the substance's triple-point pressure. The reverse process (gas to solid) is called deposition or desublimation. Common examples include dry ice (solid CO₂), iodine crystals, camphor, and naphthalene. In atmospheric science, sublimation of glacial ice without prior melting is an observed consequence of low atmospheric pressure and low humidity, relevant to the accelerated mass loss of Himalayan glaciers — monitored by the National Institute of Hydrology under India's National Action Plan on Climate Change.

✍️ Usage in a UPSC answer

Accelerated sublimation of Himalayan glacial ice under conditions of low humidity and high solar radiation has been documented by the National Institute of Hydrology as a significant contributor to the net mass balance deficit of glaciers feeding the Indus, Ganga, and Brahmaputra river systems.

Synonyms

vaporisation (solid-to-gas)volatilisationsolid evaporation

Antonyms

deposition (reverse: gas to solid)condensation (gas to liquid)melting (solid to liquid)

🌱 Word Family

sublime (verb/adjective), sublimate (verb/noun), sublimed (adjective), sublimatory (adjective), desublimation (noun — reverse process)

🔡 Root

Latin sublimare = to elevate, to lift up; from sublimis = lofty, elevated (from sub- = up from below + limen = threshold or līmus = slanting upward)

📜 Etymology

From Latin sublimatio (elevation, exaltation), a noun from sublimare (to raise aloft, to refine), derived from sublimis (lofty, high — from sub- = up from below and possibly limen = lintel/threshold). Medieval alchemists used sublimatio to describe the purification of substances by heating them so that they vaporised and re-condensed, which appeared to 'elevate' the substance to a purer form. The physical chemistry meaning — direct solid-to-gas transition — retained this sense of bypassing the 'lowly' liquid state and going straight upward to vapour.

🧠 Memory Hook

Sublimation = sublimare (to lift up) — the solid lifts itself UP directly into vapour, skipping the liquid stage entirely. Think of dry ice releasing fog-like CO₂ directly from a white solid: no puddle, no liquid — just solid going straight UP to gas, as if elevated above the ordinary.

⚗️ General Science 📖 Seen in: Human Body Systems — Organ Systems, Ph...

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