What conditions can cause icing on an aircraft?

The conditions that lead to icing on an aircraft primarily involve a combination of moisture in the atmosphere and temperatures at or below freezing. When the temperature is below freezing, any available moisture—whether from clouds, precipitation, or supercooled water droplets—can freeze upon contact with the aircraft's surfaces. This accumulation of ice can significantly affect the aircraft's performance, including increasing weight, altering aerodynamics, and possibly affecting engine performance.

While high temperatures and humidity can create conditions for condensation and fog, they do not typically lead to icing. Cloudy skies and turbulence may be experienced in the same weather systems where icing is possible, but they are not direct causes of icing. Similarly, clear skies and cold temperatures might suggest conditions conducive to freezing, but without moisture, icing would not occur. Therefore, the specific combination of sub-freezing temperatures and the presence of moisture precisely outlines the conditions that lead to aircraft icing.