From OpenStreetMap Wiki
|man_made = frost_fan|
|A device to stop frosts from damaging crops|
|Used on these elements|
|Tools for this tag|
A device to stop frosts from damaging crops. Frost fans are placed inside fields and orchards and appear as a large propeller on a pole.
How to Map
Add a node at the location of the fan and use the man_made=frost_fan.