Calculations based on long strings of observations (1961 - 2010) have shown that average values of total nebulosity in the 6 locations from Barlad hydrographic basin (Negresti, Vaslui, Barlad, Tecuci, Oncesti si Plopana) have ranged between 5.9 and 6.3 tenths. For the agricultural character of the Barlad hydrographic basin a major importance is held by the genetically related clouds type which has the largest share in rainfall production (T. Bradu, 2004). To give expression drawn graphs I made pairs of clouds types: altostratus (As) and nimbostratus (Ns), with long-term precipitations falling as rain, snow and ice pellets, stratocumulus (Sc) and stratus (St), generally producing precipitations as rain, snow and drizzle, and cumulus clouds (Cu) that can evolve into cumulonimbus (Cb), with rain falling in the aversion form.