Assertion (A): Anti-cyclonic 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 with low temperatures.

Assertion A is true because during winter, the landmass in Northern India cools down significantly. This low temperature leads to the cooling of the air above it, making the air dense and heavy, which creates a high-pressure center. High pressure combined with low temperature is the fundamental requirement for the formation of anti-cyclonic conditions, where air sinks and moves outwards in a clockwise direction.

Reason R is false because it reverses the cause-and-effect relationship. Anti-cyclonic conditions are characterized by clear skies and stable air, which actually represent the absence of rain. Winter rainfall in Northern India is caused by external weather systems called Western Disturbances, which are cyclonic in nature. Rainfall does not cause anti-cyclones; rather, the high-pressure anti-cyclonic system is established first due to the cold weather, and it is occasionally interrupted by the arrival of rain-bearing Western Disturbances.