Definition
A microburst is a small-scale, intense downdraft of air descending from a thunderstorm or rain shower that, on reaching the ground, spreads outward in all directions. Microbursts typically affect an area less than 2.5 miles across, last about 5 to 15 minutes from initial impact to dissipation, and can produce downdrafts exceeding 6,000 feet per minute and horizontal winds approaching 45 knots, resulting in a 90-knot shear (headwind to tailwind change) for an aircraft flying through one.
Plain English
A microburst is a sudden, powerful column of air that drops out of a storm cloud, hits the ground, and blasts outward like water from a hose hitting pavement. It is small, short-lived, and extremely violent — strong enough to push an airplane down hard and rob it of lift in seconds.
Context Anchor
Pilots encounter this term in weather discussions, airport wind warnings, and training about takeoff and landing hazards near thunderstorms or heavy rain showers.
Derivation
From 'micro' (Greek 'mikros', meaning small) and 'burst' (a sudden, forceful release). The name reflects that this is a small-scale but violent burst of descending air — distinguishing it from larger-scale downbursts that cover a wider area.
Why Pilots Care
Microbursts produce extreme wind shear that can cause sudden loss of airspeed and altitude during takeoff or landing, often leading to loss of control if the pilot does not recognize the signs and execute an immediate escape maneuver.
Analogy
Picture water poured hard onto a flat floor: it hits one spot, then rushes outward in every direction. A microburst acts similarly, except the moving material is air.
Grounding Statement
Picture a bucket of water poured straight down onto a driveway: it hits hard, then spreads outward fast in every direction. A microburst does the same thing with air, but on a scale large enough to overwhelm an airplane.
Intuition Check
Do not let the word “micro” make this sound harmless. Here, “micro” means the affected area is small; the wind inside it can be extremely strong.
Example Sentence 1
The crew delayed departure after the tower reported a microburst alert near the approach end of the runway.
Example Sentence 2
During the preflight briefing the instructor pointed out that microbursts can form under any tall cumulus cloud, not just fully developed thunderstorms.