diff --git a/docs/src/IceNucleationParcel0D.md b/docs/src/IceNucleationParcel0D.md
index 5aeb800d55..7d11c3f50a 100644
--- a/docs/src/IceNucleationParcel0D.md
+++ b/docs/src/IceNucleationParcel0D.md
@@ -223,12 +223,12 @@ Following the water activity based immersion freezing model (ABIFM), the ABIFM d
   per second via immersion freezing can then be calculating using
 ```math
 \begin{equation}
-  P_{ice, immer} = \left[ \frac{dN_i}{dt} \right]_{immer} = J_{immer}A(N_{liq})
+  P_{ice, immer} = \left[ \frac{dN_i}{dt} \right]_{immer} = J_{immer}\;A_{aero}(N_{liq})
   \label{eq:ABIFM_P_ice}
 \end{equation}
 ```
 where ``N_{liq}`` is total number of ice nuclei containing droplets and
-  ``A`` is surface area of those droplets.
+  ``A_{aero}`` is surface area of the ice nucleating particle.
 
 ## Homogeneous Freezing
 Homogeneous freezing follows the water-activity based model described in the
diff --git a/parcel/Immersion_Freezing.jl b/parcel/Immersion_Freezing.jl
index 2f279a812f..1282e53c05 100644
--- a/parcel/Immersion_Freezing.jl
+++ b/parcel/Immersion_Freezing.jl
@@ -22,7 +22,7 @@ R_d = TD.Parameters.R_d(tps)
 Nₐ = FT(0)
 Nₗ = FT(500 * 1e3)
 Nᵢ = FT(0)
-r₀ = FT(1e-6)
+r₀ = FT(1e-6)       # radius of droplets
 p₀ = FT(800 * 1e2)
 T₀ = FT(251)
 qᵥ = FT(8.1e-4)
diff --git a/parcel/parcel.jl b/parcel/parcel.jl
index 56dc3b8639..ef77cb3cb9 100644
--- a/parcel/parcel.jl
+++ b/parcel/parcel.jl
@@ -127,8 +127,8 @@ function parcel_model(dY, Y, p, t)
             #A = N_liq* λ^2
             r_l = 2 / λ
         end
-        A_l = 4 * FT(π) * r_l^2
-        dN_act_dt_immersion = max(FT(0), J_immersion * N_liq * A_l)
+        A_aero = 4 * FT(π) * r_nuc^2
+        dN_act_dt_immersion = max(FT(0), J_immersion * N_liq * A_nuc)
         dqi_dt_new_immers = dN_act_dt_immersion * 4 / 3 * FT(π) * r_l^3 * ρ_ice / ρ_air
     end
     if "P3_het" in ice_nucleation_modes