What atmospheric phenomenon is characterized by strong downdraughts that are colder than the surrounding air?

A microburst is a localized column of sinking air, typically found in thunderstorms, that produces strong downdraughts. This phenomenon occurs when cold air, which accumulates at higher altitudes during a thunderstorm, descends rapidly and spreads out upon reaching the ground. The result is a powerful burst of wind that can be dramatically colder than the surrounding air. This rapid change in temperature and pressure can lead to severe turbulence and hazardous flying conditions, particularly for aircraft during takeoff and landing.

In contrast, a heatwave is a prolonged period of excessively hot weather, which does not involve significant downdraughts or localized cooling. Turbulence refers more broadly to irregular motion of the air, which can include a variety of atmospheric disturbances, but does not specifically define the colder downdraught characteristic of a microburst. An updraft is the opposite phenomenon to a microburst, representing a column of rising air rather than descending cold air. Hence, the defining feature of a microburst being strong, cold downdraughts distinguishes it as the correct answer.