Certified Flight Instructor - Flight Instructor Airplane Practice Exam

Which type of middle-level clouds is characterized by precipitation such as rain or snow that can create significant icing hazards?

1. Nimbostratus

2. Altostratus lenticular

3. Altocumulus castellanus

4. Stratus

The correct answer is: Nimbostratus

Nimbostratus clouds are characterized by their thick, uniform dark appearance, and they are typically associated with continuous precipitation. This type of cloud forms in stable atmospheric conditions and usually extends over large areas. Due to their extensive vertical development, nimbostratus clouds can contain significant moisture, which often results in steady rain or snow. One of the key reasons nimbostratus clouds pose a significant icing hazard is due to their lasting precipitation, which can lead to the accumulation of ice on the aircraft. As aircraft fly through these clouds, especially in colder temperatures, the supercooled water droplets can freeze upon contact with the aircraft surfaces, leading to potential aerodynamic issues and reduced aircraft performance. In contrast, other types of clouds mentioned, such as altostratus and altocumulus castellanus, may not consistently produce the same level of significant precipitation and associated icing conditions as nimbostratus clouds. Altostratus can lead to light rain or snow but is less likely to produce persistent icing hazards compared to the extensive and continuous precipitation found with nimbostratus. Stratus clouds may yield light precipitation, but it is typically not as significant as that associated with nimbostratus clouds. As a result, nimbostratus is the