The high Peak to Average power Ration (PAR) levels of Orthogonal Frequency Domain Multiplexing (OFDM) signals forces to the utilization of linear power amplifiers. However, linear amplifiers have low power efficiency which is problematic considering that battery life is a critical resource in mobile systems; also linear amplifiers have a clipping effect when considered as a limiter. Amplifier nonlinearities affect drastically the performance of OFDM systems. In this paper, the effects of Clipping and amplifier nonlinearities are modeled in an OFDM system. We showed that the distortion due to these effects is highly related to the dynamic range it self rather than the clipping level or the saturation level of the nonlinear amplifier. Computer simulations of the OFDM system using Matlab are completely matched with the deduced model in terms of OFDM signal quality metrics such as BER, ACPR and EVM.