Fig. 4

a Photograph and b schematic illustration of the experimental setup used to test the real-time radiative cooling performance of the 3D trench-like PMRC film. c Ambient temperature (red line), and temperature of PMRC film (blue line), d humidity level, and e solar irradiance during midday on a clear sky day in Weihai city. f Ambient temperature (red line), and temperature of PMRC film (blue line), and g humidity level during nighttime on a clear sky day in Weihai city. h Measured cooling powers of the PMRC film (red line) and ambient temperatures (blue line) during midday on a clear sky day in Weihai city