O
- observational astronomy (see "light pollution" in places)
- observatory (see also list of observatories)
- occultation
- oceanic climate
- Office of Oceanic and Atmospheric Research (OAR)
- 1999 Oklahoma tornado outbreak
- orographic lift
- oxygen
- oxygen cycle
- ozone
- ozone depletion
- ozone depletion potential (ODP)
- ozone layer (ozonosphere layer)
- ozone-oxygen cycle
Read more about this topic: Index Of Meteorology Articles