Correct Option
A sudden fall in barometer reading indicates a rapid decrease in atmospheric pressure. This condition typically signifies the approach of a low-pressure system. Low-pressure systems are generally associated with unstable atmospheric conditions, leading to the formation of clouds, precipitation, strong winds, and stormy weather.
Incorrect Options
b) Calm weather: Calm and stable weather conditions are usually associated with high-pressure systems, where atmospheric pressure is relatively high or rising, not falling suddenly.
c) Cold and dry weather: This type of weather is often observed under the influence of stable high-pressure systems, particularly in winter, which are characterized by high or rising barometric pressure, not a sudden drop.
d) Hot and sunny weather: Clear skies and hot, sunny conditions are typically indicative of stable high-pressure systems. These systems are characterized by descending air, which suppresses cloud formation and leads to calm, settled weather, contrary to a sudden fall in barometric pressure.