The Thermal Blocking Layers in the 100-meter Earthbound Layer of the Air over Cracow The paper is based on five-year measurements of the air temperature made for the period 1970—1974 in 3 stations located in the centre and periphery of Cracow. One of the stations surpasses the two others at about 110 m. Each of the stations represents different mesoclimatic region. As a base for analysis vertical and horizontal gradients of the air temperature were taken. Special attention was paid to the differences of the frequency of the appearances of temperature inversion and isotherm between the centre and periphery areas. The results showed considerable differences of the air stratification above examining territoiries. The temperature inversion more often appear over the periphery than the centre area, specially in the midday and in the evening. The intensity of inversions is mostly higher over the periphery. These characteristics are related to the differentiation of the vertical extent of heat island over the two areas and to the differences regarding the extent of convection and turbulence. Twenty-four hours temperature inversions appear mostly while the air flow from the south and south-west, and most of them belong to the radiation inversions. The horizontal gradient of temperature between stations representing the centre and periphery areas, which are 4,9 km away, hold within the values: from -0,9°C/km to l,5°C/km. The negative values of horizontal temperature gradients appear comparatively rare but they may occur in any month and at any term.