explained collected

docs/src/P3Scheme.md

@@ -206,7 +206,7 @@ Collisions are calculated through the following equation:
   - ``m_x(D)`` - mass of given species x at diameter D
   - ``V_x(D)`` - Chen terminal velocity of given species x at diameter D 
 
-  In our parametrization we take ``E_ci = 1`` and ``A(D_i, D_c) = \pi \frac{(D_i + D_c)^2}{4}``. 
+  In our parametrization we take ``E_ci = 1`` and ``A(D_i, D_c) = \pi \frac{(D_i + D_c)^2}{4}``. We also assume that if the temperature is above freezing then ice particles get collected, otherwise the colliding species is collected by the ice.  
 
   Furthermore, the distributions of non-ice species are taken to be of the following forms: 
   - cloud water: ``N_0 D^8 e^{-\lambda D^3}``