diff --git a/pvlib/data/variables_style_rules.csv b/pvlib/data/variables_style_rules.csv
index 1954e036c2..f7930bd445 100644
--- a/pvlib/data/variables_style_rules.csv
+++ b/pvlib/data/variables_style_rules.csv
@@ -11,7 +11,7 @@ ghi;global horizontal irradiance
 ghi_extra;horizontal irradiance at top of atmosphere (extraterrestrial)
 gri;ground-reflected irradiance
 ape;average photon energy
-aoi;angle of incidence between :math:`90\deg` and :math:`90\deg`
+aoi;angle of incidence. Angle between the surface normal vector and the vector pointing towards the sun's center
 aoi_projection;cos(aoi)
 airmass;airmass
 airmass_relative;relative airmass