deploy: 0a1d955

Author: oscarbranson

04_atmosphere/l21.html

@@ -476,7 +476,7 @@ <h2>Examples of first order decay<a class="headerlink" href="#examples-of-first-
 <p>Photolysis is a good example of first order decay.
 Here the rate of change of our species (say <span class="math notranslate nohighlight">\(\mathrm{NO_2}\)</span>) is dependent on the photolysis coefficient.
 This depends on the flux of photons from the sun, the absorption cross-section of <span class="math notranslate nohighlight">\(\mathrm{NO_2}\)</span> and its quantum yield.
-The main challenge is to calculate <span class="math notranslate nohighlight">\(J_\mathrm{NO_2}\)</span> (see <code class="xref std std-numref docutils literal notranslate"><span class="pre">lecture_23</span></code>).</p>
+The main challenge is to calculate <span class="math notranslate nohighlight">\(J_\mathrm{NO_2}\)</span> (see <code class="xref std std-numref docutils literal notranslate"><span class="pre">lecture_20</span></code>).</p>
 <p>The rate of a heterogeneous process is usually expressed in terms of the uptake coefficient, <span class="math notranslate nohighlight">\(\gamma\)</span>, which is defined as the fraction of molecules colliding with the surface that are permanently lost from the gas phase.</p>
 <p>According to the kinetic theory of gases, the rate of collision of a species <span class="math notranslate nohighlight">\(\mathrm{A}\)</span> at the surface, per unit area, is <span class="math notranslate nohighlight">\(\mathrm{[A]} \frac{c}{4}\)</span>,
 where <span class="math notranslate nohighlight">\(\mathrm{[A]}\)</span> is the concentration (<span class="math notranslate nohighlight">\(\mathrm{molecules \ cm^{-3}}\)</span>) of species <span class="math notranslate nohighlight">\(\mathrm{A}\)</span> and <span class="math notranslate nohighlight">\(c\)</span> is the mean molecular speed of the gas molecules (<span class="math notranslate nohighlight">\(= \sqrt{\frac{8RT}{\pi M}}\)</span>).</p>

_sources/04_atmosphere/l21.md

@@ -165,7 +165,7 @@ In the atmosphere there are many examples of compounds that can be considered to
 Photolysis is a good example of first order decay.
 Here the rate of change of our species (say $\mathrm{NO_2}$) is dependent on the photolysis coefficient.
 This depends on the flux of photons from the sun, the absorption cross-section of $\mathrm{NO_2}$ and its quantum yield.
-The main challenge is to calculate $J_\mathrm{NO_2}$ (see {numref}`lecture_23`).
+The main challenge is to calculate $J_\mathrm{NO_2}$ (see {numref}`lecture_20`).
 
 The rate of a heterogeneous process is usually expressed in terms of the uptake coefficient, $\gamma$, which is defined as the fraction of molecules colliding with the surface that are permanently lost from the gas phase.
 
@@ -213,7 +213,7 @@ In the example above we have implicitly made the assumption that $\mathrm{[OH]}$
 Steady state was introduced in the chain reaction at the start of the lecture (and in 1A Chemical Kinetics).
 Steady state is an important approximation we often make use of in the atmosphere.
 Many pollutants are in steady state because their chemical loss processes are fast.
-How fast do they need to be? It depends on over what timescale we are interested in.
+How fast do they need to be? It depends on over what timescale we are interested in. 
 As we saw in {numref}`lecture_20` $\mathrm{[NO_2]}$ has changed a lot over the last 165 years.
 However, day to day we say that the $\mathrm{[NO_2]}$ is fairly similar.
 During the COVID pandemic what caused the large decrease in $\mathrm{[NO_2]}$ was a change in its emissions (source) rather than a change in its loss (sink).