Aerosol sprays smell strongest, immediately, close to the source.
Gradually, the odor permeates even the corners of the room, and, once it is uniformly spread throughout the space in the room, it is said to have diffused. One way is to trace the positions of things that are being diffused at different times. Torsten Hagerstrand, a Swedish geographer at the University of Lund, used the following technique to trace the diffusion of an innovation. Hagerstrand traces the diffusion process by imitating it with numbers. Such imitation, leading to prediction or forecasting of the pattern of diffusion, is called a simulation of diffusion.