Surface weather observation

From Glossary of Meteorology

surface weather observation

An evaluation of the state of the atmosphere as observed from a point at the surface of the earth, as opposed to an upper-air observation.

This term is applied mainly to observations that are taken for the primary purpose of preparing surface synoptic charts. Major types of surface observation are synoptic weather observation, aviation weather observation, and marine weather observation. Climatological observations may also be included.