deletions | additions       diff --git a/The_column___dryair_is__.tex b/The_column___dryair_is__.tex  index dcb3b1a..afbe904 100644  --- a/The_column___dryair_is__.tex  +++ b/The_column___dryair_is__.tex 
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The column$_{dryair}$ is calculated from the measured surface pressure (P$_s$). The effect of varying water vapour on the surface pressure can be removed by using the retrieved vertical column of H$_2$O from the spectra. \math{column$_{dryair}$} \mathrm{column$_{dryair}$}  is therefore calculated as per Equation \ref{eq:col_dryair}. \begin{equation}  \label{eq:col_dryair}