An apparatus for generating a defined environment for particle-shaped samples, comprises a support element with a rest end for a particle-shaped sample and an apparatus for generating a humid gas flow at a mouth end thereof. The mouth end is directed to the rest end. A gas provider provides gas having a first dew-point temperature. A cooler cools the gas to a cooler temperature under condensation of moisture to adjust a second dew-point temperature of the gas. A guide guides the gas with the second dew-point temperature to the mouth end, preventing condensation of moisture from the gas. A controller adjusts the relative humidity of the gas at the mouth end by adjusting the cooler temperature and adjusting the temperature of the gas at the mouth end.