What does a "hook echo" indicate in weather patterns?

A "hook echo" is a specific radar signature that indicates the presence of a rotating column of air, often associated with supercell thunderstorms. This meteorological pattern is primarily linked to severe weather events, particularly the development of tornadoes. When the radar detects a hook echo, it suggests that a storm is exhibiting rotation, which can potentially intensify into a tornado.

This phenomenon occurs because the storm’s updraft spins in response to various atmospheric conditions. The hook shape is typically observed on Doppler radar images, where one part of the storm forms a hook-like feature as it wraps around the updraft. The presence of such an echo is crucial for meteorologists as it helps in issuing timely warnings for dangerous weather, assisting in the protection of life and property.

The other options do not relate to the characteristics indicated by a hook echo. Clear skies and good flight conditions are indicative of stable weather patterns, while heavy rainfall without severe weather does not involve tornadoes or storm rotation. Low visibility due to fog is a completely different weather phenomenon that does not involve the severe storm activity associated with hook echoes.