>From a fabrication standpoint here is an even simpler test for cooling radiation. It consists of a truncated cone lined with reflective mylar on the inside. The wide end is open to the sky and a thermometer is located at the vertex of the cone.
See diagram: https://drive.google.com/file/d/1p7coRgUqwzMGw40DhUQzJACCyHrd8EL5/view?usp=sharing If cooling radiation does not exist then the temperature of the thermometer should be about the same or perhaps slightly warmer when the cone is above it. However, if cooling radiation is real and has wave-like properties then the cone should focus the cooling radiation from the sky onto the thermometer and lower its temperature. Harry
