A smokestack with an effective height of $25m$ emits sulfur dioxide $(S{O}_2)$ at a rate of $10k\frac{g}{h}r$ to the surrounding rural area. Assuming unlimited mixing height, estimate the contribution of this stack to ground$-$level $S{O}_2$ concentrations at a schoolyard $8km$ down wind, if wind speed is $4\mathrm{.}5\frac{m}{s}$ on a sunny midwinter day.

$($a$)$ If we assume the mixing height is $300m,$ which is very low so that restricts the ascension of the plume. How would you change the Python code so that it can be used to solve the above problem? Paste you revised code below. $($You do not need to paste all of them, just paste the contents you revised and mention which part$/$lines they are in$.)$

$($b$)$ What would be the simulated concentration at the schoolyard then? Wite down the answer and plot the $y-z$ contour figure at $x=8km.$