Wind measuring towers (sometimes called meteorological evaluation towers (MET) are used to verify the wind characteristics at a potential site for a wind farm.
For the safety of low flying aircraft these towers must be marked properly.
FAA Advisory Circular - Obstruction Marking and Lighting
See Chapter 3 paragraph 30-34 for details on Painting and Spherical marking balls for wind measuring towers
Nebraska Department of Aeronautics
List of all registered MET towers in Nebraska
Nebraska Aviation Trades Association
Sprayer pilots are one of many users of low level air space. Proper marking of MET towers will protect pilots.
Wind measuring towers are typically just shorter than 200 feet tall. Above which a light would be required. Painted stripes and high visibility balls make the tower stand out and easier to see for low flying pilots.