This Paper presents the results of analyzing the global contour of the fundamental frequency (F0) for Arabic sentences and developing a model that represents it. The work concentrated on analyzing only affirmative and interrogative isolated read-loud sentences. The work is divided into two parts: 1) Extracting the common characteristics and differences between the F0 plots of affirmative and interrogative Arabic sentences, and 2) Analyzing the effect of change in sentences length on the characteristics and differences extracted in the first part of the study. The model obtained can be easily implemented in speech synthesizers to improve its intonation.