Find the correct ascending order of the following atmospheric layers from the earths surface.
(a) Mesosphere
(b) Thermosphere
(c) Troposphere
(d) Stratopause
(e) Stratosphere
(f) Mesopause
(g) Tropopa

Question

Find the correct ascending order of the following atmospheric layers from the earths surface.
(a) Mesosphere
(b) Thermosphere
(c) Troposphere
(d) Stratopause
(e) Stratosphere
(f) Mesopause
(g) Tropopause

UnlockIAS · Accepted Answer

Correct — option (3), '(c), (g), (e), (d), (a), (f), (b)'. The atmosphere above any point on the earth is built as an alternating stack: a layer, then the boundary that caps it, then the next layer, then its boundary, and so on. Every name ending in -sphere is a layer and every name ending in -pause is the ceiling of the layer whose root it shares. Read upward from the ground the sequence is therefore troposphere, tropopause, stratosphere, stratopause, mesosphere, mesopause, thermosphere — that is (c), (g), (e), (d), (a), (f), (b), which is exactly option (3). Two independent checks confirm it. The first is the naming rule: the tropopause must come immediately after the troposphere and before the stratosphere, the stratopause immediately after the stratosphere, the mesopause immediately after the mesosphere, and only option (3) keeps all three pairings intact. The second is the temperature profile, which is what these boundaries were defined by in the first place. In the troposphere temperature falls with height at roughly 6.5 degrees Celsius per kilometre; at the tropopause the fall stops. Through the stratosphere temperature rises with height, because ozone there absorbs ultraviolet radiation and warms the air from above; the rise ends at the stratopause. Through the mesosphere temperature falls again, reaching the lowest values found anywhere in the atmosphere at the mesopause. Above that, in the thermosphere, temperature climbs steeply again as the thin gas absorbs the shortest-wave solar radiation. Fall, rise, fall, rise — four regimes separated by three pauses. The fastest way to solve this question in the hall does not require any of that detail: the stem says 'ascending order from the earth's surface', so whatever stands first must be the layer touching the ground, and only option (3) begins with (c), the troposphere. The other three begin at the tropopause, at the mesosphere and at the stratosphere respectively, and can be struck out in a single glance.

Why the other options are wrong — (a) Begins with (g), the tropopause, placing a boundary below the layer it caps — the ceiling of the troposphere cannot lie beneath the troposphere. It then compounds the error by putting the stratopause (d) before the stratosphere (e), inverting the same relationship a second time, and it ends with the thermosphere buried in the middle while the mesosphere is pushed to the top of the atmosphere. A candidate who applies the single test 'what touches the ground' rejects this option before reading past its first entry.  (b) Starts at the mesosphere, roughly 50 km up, and only reaches the troposphere in fifth place — so the layer holding almost all the atmosphere's mass, its water vapour and all its weather is stacked above the thermosphere. The internal pairings are partly sound, mesosphere-mesopause and troposphere-stratopause aside, which is what makes it tempting to a candidate who is checking pairs without checking the base. Order questions must be anchored at one end first; here the anchor is the ground.  (d) Starts at the stratosphere and omits the troposphere from the base entirely, dropping it into fifth place immediately after the tropopause. This is the most plausible-looking of the three wrong options because its first three entries — stratosphere, stratopause, mesosphere — are in genuinely correct relative order; the error is that this correct fragment has been placed at the bottom of the stack instead of in the middle. It is a reminder that a correct sub-sequence proves nothing about the whole.

Concept: The atmosphere is divided vertically by how temperature behaves with height, not by composition, because up to about 80 km the gases are well mixed and composition alone would give no boundaries at all. Four regimes are recognised. The troposphere, extending from the surface to roughly 8 km over the poles and 18 km over the equator, is heated from below by the earth's surface, so temperature falls with height at an average lapse rate of about 6.5 degrees per kilometre; it holds roughly three-quarters of the atmosphere's mass, nearly all its water vapour, and all its weather. The stratosphere, reaching to about 50 km, is heated from above by ozone absorbing ultraviolet radiation, so temperature rises with height, which makes it stable, cloudless and largely free of turbulence — the reason long-haul jets cruise in its lower part. The mesosphere, to about 80 km, has no such heat source and cools with height to the lowest temperatures in the whole atmosphere; it is dense enough to burn up most incoming meteors. Above the mesopause the thermosphere absorbs extreme ultraviolet and X-radiation and its temperature rises steeply, though the gas is so rarefied that the heat content is negligible. Each regime is closed by a 'pause' — tropopause, stratopause, mesopause — at which the temperature trend reverses.

State PCS 2026 Q26 — Geography PYQ with Answer

State PCS 2026 Q26 — Geography PYQ with Answer