In underwater optical wireless communication (UOWC) channels, impulse response is widely used to describe the temporal dispersion of the received signals. In this paper, we propose a new function to model the impulse response in most realistic cases in UOWC channels. By exploiting the inherent properties of such channels, our newly proposed model is superior to the conventional weighted double gamma functions (WDGF) model in explaining the behavior of the channel. We use Monte Carlo simulation to verify that our newly proposed model has a better accuracy of numerical fitting in most cases. Therefore, this new modeling approach offers a more convenient way to evaluate the performance of different kinds of UOWC channels.