Visual signal and Wind sock

Visual signal noun - A signal that involves visual communication.

Wind sock and visual signal are semantically related. In some cases you can replace phrase "Wind sock" with "Visual signal", this phrases are similar.

Wind sock noun - A truncated cloth cone mounted on a mast; used (e.g., at airports) to show the direction of the wind.

Visual signal and wind sock are semantically related. You can use "Visual signal" instead a noun phrase "Wind sock".