Which type of clouds typically have little effect on flying?

High clouds generally have little effect on flying because they are typically located at altitudes above 20,000 feet and consist mostly of ice crystals, which means they are associated with stable atmospheric conditions. These clouds include cirrus, cirrostratus, and cirrocumulus, which do not usually bring significant turbulence or adverse weather conditions, allowing for safer and more stable flight. Their high altitude and thin nature often mean they are not accompanied by the types of turbulence or precipitation that can impact aircraft performance.

In contrast, stratiform clouds can create extensive cloud cover and light precipitation, affecting visibility and potentially leading to icing conditions, while cumuliform clouds, particularly cumulus and cumulonimbus, are associated with turbulent air and can lead to severe weather events like thunderstorms. Low clouds can also bring about low visibility conditions and turbulence, which are less favorable for flying. Thus, high clouds are deemed to have minimal impact on flying, primarily due to their nature and altitude.