Definition
A day on which suspended particles in the lower atmosphere — typically dust, smoke, or fine moisture — reduce horizontal visibility and obscure the natural horizon, even though flight may still be legal under visual flight rules.
Plain English
A day when the air looks milky or smoky, making it hard to see the horizon clearly even though you can still fly visually.
Context Anchor
Seen during visual flying, especially when using the horizon or ground objects to judge the airplane’s position and movement.
Derivation
‘Haze’ comes from an old English nautical term meaning thick or foggy air. A hazy day is one where the air carries enough fine particles to soften and blur what the pilot sees outside.
Why Pilots Care
Reduced contrast can lead to misjudged distances and altitudes, increasing the chance of flying too low or drifting off the intended ground track.
Grounding Statement
Imagine looking across a valley through thin smoke — you can see the ground below you, but the line where earth meets sky is washed out and hard to pin down.
Intuition Check
Hazy does not mean the same thing as cloudy. On a hazy day the sky may look mostly open, but the air between you and what you are looking at makes things less sharp.
Example Sentence 1
On a hazy day, the instructor had the student rely more on the airplane's pitch attitude than on the faded horizon.
Example Sentence 2
On a hazy day the pilot used a higher altitude to maintain visual contact with the chosen road for the maneuver.