Simulations of atmospheric diffusion process under various atmospheric stability conditions were carried out with a thermally stratified wind tunnel of IHI. We took Pasquill-Gifford Chart as a template of typical plume spread width. Simulated plume spread widths were good agree with characteristic lines of each atmospheric stability condition that was categorized by Pasquill in the chart. Turbulent intensities were widely distributed according with stability conditions, as real atmospheric phenomenon. We conclude that fundamental plume spread patterns of each Pasquill's stability category are able to be simulated in the wind tunnel.