New particle formation (aerosol nucleation) happens frequently in the troposphere. It has a large impact on the aerosol lifecycle and can substantially change the number concentrations of cloud condensation nuclei (CCN) and ice-nucleating particles. Consequently, it may significantly affect cloud properties and the associated precipitation processes. Here we use a global atmospheric model to investigate the impact of various new particle formation mechanisms on warm and cold cloud processes and the anthropogenic aerosol forcing estimate. The model we use is the atmosphere component of the Energy Exascale Earth System Model (E3SM), with a revised Modal Aerosol Module that has a nucleation mode to represent the evolution of newly formed particles more explicitly. Results show that both the boundary layer nucleation and free-troposphere binary nucleation mechanisms have a large influence on the CCN number concentration and liquid cloud formation, and their impacts are sensitive to the dimethyl sulfide (DMS) emission flux perturbation in the model. In addition, the free-troposphere nucleation greatly increases the number concentration of sulfate solution droplets that promote the homogeneous ice nucleation in cirrus clouds. We find the two nucleation mechanisms have very different impacts on the estimated anthropogenic aerosol effect, with opposite signs in some regions. This suggests that it’s important to improve/constrain the representation of new particle formation and its interaction with both warm and cold cloud processes in global aerosol-climate models.