NOVELTY - Cooling material (30) comprises particles (32) that are arranged to generate surface plasmon resonances having a wavelength within an atmospheric window wavelength in which atmosphere of the earth has greatly reduced average absorption and emission compared with average absorption and emission in an adjacent wavelength. The material is arranged for emission of thermal radiation associated with generated surface plasmon resonances and absorption of radiation originating from the atmosphere is greatly reduced; and also comprises layer or foil comprising polymeric material (34).    USE - For cooling interior spaces of buildings; to refrigerate food; to condense water; and for reducing the temperature of objects.    ADVANTAGE - The cooling material comprises particles having a diameter of 10-100 (preferably 50, especially less than 50) nm. The reflective material has a large portion of incident radiation is reflected away from the cooling material and consequently thermal absorption of radiation having a wavelength within or outside the atmospheric window is reduced, which increases cooling efficiency.    DETAILED DESCRIPTION - A cooling material (30) comprises particles (32) that are arranged for generating surface plasmon resonances having a wavelength within an atmospheric window wavelength in which atmosphere of the earth has greatly reduced average absorption and emission compared with the average absorption and emission in an adjacent wavelength, where the cooling material is arranged for emission of thermal radiation associated with the generated surface plasmon resonances and absorption of radiation originating from the atmosphere is greatly reduced. The cooling material is arranged to reflect at least some incident radiation; and comprising a layer or foil that comprises a component material that is substantially transmissive for a wavelength inside and outside the atmospheric window wavelength. The layer or foil comprises a polymeric material (34). The particles are arranged so that at least some of the resonant surface plasmons have a wavelength within the wavelength of 3-5 mu m and/or 7.9-13 mu m. The particles comprise SiC. An INDEPENDENT CLAIM is included for method of cooling a material involving generating surface plasmons in the particles; and emitting at least a portion of the energy associated with the resonant surface plasmons from the particles in form of radiation having a wavelength within the atmospheric window wavelength range.    DESCRIPTION OF DRAWING(S) - The figure shows a perspective view of cooling material.    Cooling material (30)    Particles (32)    Polymeric material (34)