What meteorological phenomenon involves a rapid increase in indicated airspeed during a thunderstorm?

A microburst is a localized column of sinking air within a thunderstorm, which can result in a significant and sudden increase in indicated airspeed as an aircraft approaches the phenomenon. This occurs because the microburst can produce strong downdrafts that push air downwards rapidly. As an aircraft flies into this area, the sudden influx of air leads to an increase in airspeed until the aircraft reaches the core of the microburst. Once the aircraft exits this high-speed environment, it may experience a rapid loss of performance and potential stall risk, underscoring the dangers associated with navigating near or through thunderstorms.

The other options describe different atmospheric conditions. Updrafts refer to upward-moving air in a thunderstorm, which primarily contribute to the development of the storm itself but do not directly relate to a rapid increase in indicated airspeed. Downdrafts, while related to microbursts, specifically refer to the downward movement of air but do not encapsulate the sudden increase in aircraft indicated airspeed that characterizes a microburst. Turbulence is a broader term for irregular motion of the atmosphere, which might occur in thunderstorms but does not specifically define the rapid change in airspeed related to microbursts. Thus, the microburst accurately represents the phenomenon of