Under which conditions will the atmosphere be most stable? (Note: surface wind speed is measured at 10 m above the ground)

Correct option is C

Explanation:
Atmospheric stability is highest when vertical mixing is minimized, which occurs under the following conditions:
· Clear skies at night lead to radiative cooling of the ground, making the air near the surface colder than the air above, creating a temperature inversion, which is a very stable condition.
· Light winds (2–3 m/s) allow the inversion to persist — strong winds would mix the air and reduce stability.
Thus, clear night + light wind = maximum atmospheric stability.
Information Booster:
· Stable atmosphere resists vertical motion, leading to poor dispersion of pollutants (common during clear, calm nights).
· Unstable atmosphere occurs during sunny days, especially with strong heating, promoting vertical mixing.
Additional Information:
· (a) Cloudy night: Clouds trap heat and reduce inversion — less stable.
· (b) Cloudy summer day: Daytime heating encourages mixing — unstable.
· (d) Wind speed <2 m/s can promote stagnation but also may lead to surface turbulence at very low levels — not as effective in supporting inversion as condition (c).