The vertical thermal gradients of negative sense indicate the presence of thermal inversions with different frequencies and intensities that vary in the five groups of points of climatic observation:
a. between Rogojeşti and the point Viţcani Bază, they have a percentage of 100%, indicating the maximum favorable production of thermal inversions.
b. from the total number of cases, between Roman and the point Viţcani Deal and Rogojeşti and the point Viţcani Deal, the thermal gradients of negative sense had a percentage of 33% and 23% respectively, indicating the production of thermal inversions of lower frequency.
c. the fewer thermal inversions were produced between Suceava – Rogojeşti and Roman – Suceava, in the studies period the negative thermal gradients having the lowest percentage of 17% and 11% respectively. The exclusive analysis of the Northern part of the Siret Valley emphasized a high frequency of thermal inversion, in most cases relative inversions, with reduced time and frequency.