Assertion (A): Anticyclonic conditions are formed in winter season when atmospheric pressure is high and air temperatures are low. Reason (R): Winter rainfall in Northern India causes development of anticyclonic conditions.

Answer: (c) A is true but R is false.

A is true: cold winter air gives high pressure and anticyclonic conditions. R is false: winter rain in north India comes with western disturbances, which are low-pressure (cyclonic) systems.

The idea

An anticyclone is a high-pressure system with generally sinking air and outward surface winds. Winter cooling of a large landmass favours dense air and high surface pressure. Winter rain in northern India usually arrives with passing low-pressure disturbances, so rainfall is not the basic cause of the seasonal high-pressure pattern.

Land loses heat in winter → Near-surface air cools → Dense cold air favours high surface pressure → Sinking air limits cloud growth → Clear spells permit further night-time cooling

Why the others are wrong

(a) Winter rain does not create the high pressure; cold, dense air does.

(b) R is not just unrelated, it is false.

(d) A is true.

The trap

Rain and cold arrive in the same season, so R sounds like a cause. Rain comes with lows, not highs.

Also know

Around a surface high, winds turn clockwise in the Northern Hemisphere and anticlockwise in the Southern Hemisphere. Around a low, these directions reverse. Clear, calm winter nights can produce a temperature inversion, with cold air trapped below warmer air.