RAP r's ( continued) a while after a 1% line has expanded it gete so diluted Ehat the central concentration falls down end these shells co tract again. visualize it. I think this next picture will help you This top section is the peak concentration, shows how ths hottest part of the cloud varies. It is right in the center of the cloud and it starts out at aod falls rapidly in hours it is 10%, This lower f shows the heicht of the spherical shells that contain a certain fraction of the initial materials. You will ne that the 10% line immediately starts to contract due to the dilution of the cloud and it disappears in when 10% is precisely at the center of the cloud. hours The 1% line continucs to expand for about 12 hours and then it Hd slowly starts to contract and these other ones are still expanding out here about 2), hours. This is the type of diffusion picture we have used and now lets go back and Look at this one again. VOICE: How do you compute thia? BAPPs This comes out of the Fickian diffusion law. Ve used a diffusion coefficient of approximately 105 centissters second and this is siaply the solution to the equation. SPENCSs I don't believe that it matéhea with the instrument re ings that were taken in Favada. Department «f Ceasery Hist Tale S/