What is the lowest temperature that water droplets may remain in a liquid state?

The lowest temperature that water droplets can remain in a liquid state is indeed negative forty degrees centigrade. This phenomenon occurs due to the concept of supercooling. Under certain conditions, pure water can remain in a liquid state well below its freezing point of zero degrees centigrade. When water is sufficiently purified and free of impurities or nucleation sites, it can remain liquid at temperatures as low as negative forty degrees centigrade without forming ice.

In nature, this can be observed in certain atmospheric conditions, where supercooled water droplets exist in clouds at temperatures much lower than freezing. These droplets can coexist in a liquid state until they encounter something that triggers crystallization or freezing, such as contact with particles or nucleation sites.

Understanding this behavior is crucial in fields such as meteorology and aviation, where knowing the state of water at low temperatures can impact weather phenomena and aircraft operation in cold conditions. Other temperature choices provided do not reflect the phenomenon of supercooling, as they are above the threshold at which water can still be liquid under specific conditions, so they do not capture the lowest potential temperature for liquid water.