fog horizon

in atmospheric chemistry
https://doi.org/10.1351/goldbook.F02471
The top of a @F02470@ layer which is confined by a low-level temperature @I03146@ and gives the appearance of the horizon (which it actually obscures) when viewed from above, against the sky.
Source:
PAC, 1990, 62, 2167. (Glossary of atmospheric chemistry terms (Recommendations 1990)) on page 2190 [Terms] [Paper]