Definition
A strong, concentrated downward rush of air from a thunderstorm or shower that strikes the ground and spreads outward in all directions, producing damaging horizontal winds and severe wind shear. Downbursts are classified by the size of the area they affect: a macroburst covers more than 2.5 miles across at the surface and can produce damaging winds for 5 to 30 minutes; a microburst covers less than 2.5 miles across and typically lasts only 2 to 5 minutes but can produce winds in excess of 150 knots.
Plain English
A column of air that falls fast out of a storm, hits the ground, and blasts outward like water from a tap hitting a sink. It creates sudden, violent wind changes that can overpower an aircraft.
Context Anchor
Seen in thunderstorm avoidance, weather briefings, airport wind warnings, and takeoff or landing decisions near convective weather.
Derivation
From 'down' plus 'burst.' The name captures exactly what happens: a sudden burst of air directed downward. The plain name is accurate -- the danger is in how fast and how hard it hits.
Why Pilots Care
Can produce rapid loss of airspeed and altitude during critical phases of flight, requiring immediate recognition and escape maneuvers to avoid loss of control.
Grounding Statement
Picture a bucket of water poured onto pavement -- the water hits, then races outward in every direction. A downburst does the same with air, but at speeds that can exceed 150 knots near the surface.
Intuition Check
A downburst is not just heavy rain falling downward. The danger is the moving air: it drops, hits the ground, and spreads outward as strong wind.
Example Sentence 1
The crew diverted around the cell after the controller reported a downburst near the approach end of the runway.
Example Sentence 2
Preflight planning included checking for convective activity that could generate downbursts along the departure route.