What type of weather phenomena might cause the need for in-flight diversions?

Thunderstorms, icing conditions, or severe turbulence are significant weather phenomena that can drastically impact flight safety and operations, necessitating in-flight diversions. Thunderstorms can create numerous hazards, including lightning, severe windshear, heavy precipitation, and hail, all of which can compromise aircraft performance and safety. Icing conditions occur when aircraft fly through clouds with supercooled water droplets, leading to ice accumulation on critical surfaces such as wings and control surfaces, which can affect lift and maneuverability. Severe turbulence can cause abrupt and unpredictable movements of the aircraft, endangering the safety of passengers and crew and making it difficult to maintain control.

In contrast, increased visibility and clear skies, high winds paired with low humidity, and cloud cover with mild temperatures typically do not pose immediate risks that would require diversions during flight. These conditions generally allow for safe flying, whereas the phenomena outlined in the correct answer represent serious threats that require pilots to redirect their flight path for safety.