The following diploma thesis focuses on three physical quantities, which define atmospheric conditions, and on instruments to measure them. Temperature, humidity, and barometric pressure influence the air density and the related optical density. Actual atmospheric conditions have to be observed while conducting precise measurement of distances. Changes of the air refractive index have to be compensated for in the results. Equations for calculation of the actual refractive index and the actual distance acknowledge the influence of meteorological parameters on the distance values. Tests were performed on the meteorological station Meteo Station HM30. To optimise the conditions of taking temperature and humidity readings, a device for forced induction was designed, which carried the probe. The tests examined the time of thermal conditioning and possibilities of the probe set up, as well as the analysis of possible influences. The probe performed very well in the device for forced induction. No influence on the temperature readings were indicated on account of various depths and rotations of the probe. The time of thermal conditioning was equal to the time expected by the manufacturer.