sliding planar atmosphere

density distribution

$\varrho(r) = \varrho_0 \exp\left( \frac{|r - p|}{\lambda} \right)$

,

$p$

denotes the center.

for grammage/length conversion, the approximation of a flat exponential atmosphere is used, with the axis given by

$\bm a \propto p - r_0$

, where

$r_0$

is the starting point of the trajectory