Definition
Atmospheric phenomena other than precipitation that reduce horizontal visibility at the surface, such as fog, mist, haze, smoke, dust, sand, volcanic ash, and blowing snow. On a Surface Analysis Chart, visual obstructions are reported as part of the present weather at each station and indicate conditions that limit how far a pilot can see along the surface.
Plain English
Things in the air — like fog, haze, smoke, or dust — that make it harder to see across the ground, even when nothing is falling from the sky.
Context Anchor
Seen in surface analysis chart discussions and aviation weather reports when visibility is being described or explained.
Derivation
Visual comes from a Latin word meaning “sight.” Obstruction comes from a Latin word meaning “to block up.” Together, the words point to anything that blocks or limits sight, which is exactly how the term is used in weather information.
Why Pilots Care
These conditions determine whether visual flight rules remain legal and safe or whether pilots must switch to instrument procedures.
Grounding Statement
If you look across an airport and haze, fog, smoke, or blowing snow keeps you from seeing clearly, that condition is acting as a visual obstruction.
Intuition Check
Do not read visual obstructions as only physical objects blocking the view, like a building or a dirty windshield. In this weather-chart context, it usually means fog, haze, smoke, dust, snow, or other material in the air reducing visibility.
Example Sentence 1
The Surface Analysis Chart showed widespread visual obstructions across the valley, with fog reducing visibility to less than a mile at several stations.
Example Sentence 2
The pilot delayed departure after noting visual obstructions that would prevent maintaining VFR cloud clearances.