What defines a roll cloud?

A roll cloud is specifically defined as a low-level, detached tube-shaped cloud that is typically associated with thunderstorms. These clouds often form at the leading edge of a thunderstorm outflow boundary and can appear quite dramatic, as they are elongated and can look like a roll lying horizontally in the sky. Their formation is linked to wind shear and the presence of cool air descending from a thunderstorm, which can lead to the characteristic tubular shape. This feature distinguishes roll clouds from other types of clouds that may form at higher altitudes, cover broader areas, or occur in different weather conditions. Understanding the characteristics and formation conditions of roll clouds is essential for recognizing them in weather patterns, especially when monitoring thunderstorm activity.