text: To measure a PDRC surface's cooling power, the absorbed powers of atmospheric and solar radiations must be quantified. PDRC should not be measured when the surface is in a balanced or controlled state, but rather in a real-world setting. Standardized devices to measure PDRC effectiveness have been proposed.
  Evaluating atmospheric downward longwave radiation based on "the use of ambient weather conditions such as the surface air temperature and humidity instead of the altitude-dependent atmospheric profiles," may be problematic since "downward longwave radiation comes from various altitudes of the atmosphere with different temperatures, pressures, and water vapor contents" and "does not have uniform density, composition, and temperature across its thickness."