diff --git a/Metadata-standard-names.md b/Metadata-standard-names.md
index f9a9faa..a3f799c 100644
--- a/Metadata-standard-names.md
+++ b/Metadata-standard-names.md
@@ -455,9 +455,9 @@ Note that appending '_on_previous_timestep' to standard_names in this section yi
     * `real(kind=kind_phys)`: units = kg kg-1
 * `mass_fraction_of_dust_accumulation_aerosol_particles_in_air`: Mass fraction of accumulation mode dust aerosol particles
     * `real(kind=kind_phys)`: units = kg kg-1
-* `number_fraction_of_coarse_aerosol_particles_in_air`: Ratio of number concentration of coarse mode dust aerosol particles to the molecular concentration of air
+* `number_fraction_of_coarse_aerosol_particles_in_air`: Ratio of number concentration of coarse-mode dust aerosol particles to the molecular concentration of air; i.e., the ratio of the number of coarse-mode dust aerosol particles to the number of air molecules in a unit volume
     * `real(kind=kind_phys)`: units = particles molecules-1
-* `number_fraction_of_accumulation_aerosol_particles_in_air`: Ratio of number concentration of accumulation mode dust aerosol particles to the molecular concentration of air
+* `number_fraction_of_accumulation_aerosol_particles_in_air`: Ratio of number concentration of accumulation-mode dust aerosol particles to the molecular concentration of air; i.e., the ratio of the number of accumulation-mode dust aerosol particles to the number of air molecules in a unit volume
     * `real(kind=kind_phys)`: units = particles molecules-1
 ## emissions
 Emissions variables, contributed for the Community Emissions Data System (CEDS)
diff --git a/Metadata-standard-names.yaml b/Metadata-standard-names.yaml
index 62c5459..f12c23b 100644
--- a/Metadata-standard-names.yaml
+++ b/Metadata-standard-names.yaml
@@ -1072,14 +1072,16 @@ sections:
     kind: kind_phys
     units: kg kg-1
   - name: number_fraction_of_coarse_aerosol_particles_in_air
-    long_name: Ratio of number concentration of coarse mode dust aerosol particles
-      to the molecular concentration of air
+    long_name: Ratio of number concentration of coarse-mode dust aerosol particles
+      to the molecular concentration of air; i.e., the ratio of the number of coarse-mode
+      dust aerosol particles to the number of air molecules in a unit volume
     type: real
     kind: kind_phys
     units: particles molecules-1
   - name: number_fraction_of_accumulation_aerosol_particles_in_air
-    long_name: Ratio of number concentration of accumulation mode dust aerosol particles
-      to the molecular concentration of air
+    long_name: Ratio of number concentration of accumulation-mode dust aerosol particles
+      to the molecular concentration of air; i.e., the ratio of the number of accumulation-mode
+      dust aerosol particles to the number of air molecules in a unit volume
     type: real
     kind: kind_phys
     units: particles molecules-1
diff --git a/standard_names.xml b/standard_names.xml
index e45beb1..92cc2f4 100644
--- a/standard_names.xml
+++ b/standard_names.xml
@@ -797,11 +797,11 @@
       <type kind="kind_phys" units="kg kg-1">real</type>
     </standard_name>
     <standard_name name="number_fraction_of_coarse_aerosol_particles_in_air"
-                   long_name="Ratio of number concentration of coarse mode dust aerosol particles to the molecular concentration of air">
+                   long_name="Ratio of number concentration of coarse-mode dust aerosol particles to the molecular concentration of air; i.e., the ratio of the number of coarse-mode dust aerosol particles to the number of air molecules in a unit volume">
       <type kind="kind_phys" units="particles molecules-1">real</type>
     </standard_name>
       <standard_name name="number_fraction_of_accumulation_aerosol_particles_in_air"
-                   long_name="Ratio of number concentration of accumulation mode dust aerosol particles to the molecular concentration of air">
+                   long_name="Ratio of number concentration of accumulation-mode dust aerosol particles to the molecular concentration of air; i.e., the ratio of the number of accumulation-mode dust aerosol particles to the number of air molecules in a unit volume">
       <type kind="kind_phys" units="particles molecules-1">real</type>
     </standard_name>
   </section>