What Causes Vertical Accelerations?

Vertical accelerations occur whenever there is an imbalance of forces in the up–down direction—most commonly from gravity interacting with changes in lift, buoyancy, pressure, or contact forces—so anything that increases or decreases these forces relative to weight will produce upward or downward acceleration.

The Physics Behind Vertical Acceleration

At its core, vertical acceleration is governed by Newton’s second law: if the sum of vertical forces isn’t zero, an object’s vertical speed changes. Gravity pulls downward; opposing forces such as lift (aircraft), the normal force (ground and structures), buoyancy (fluids), thrust vectoring (rockets/drones), or pressure gradients (atmosphere, waves) push upward or downward. The net of these forces divided by mass sets the vertical acceleration. In everyday terms: whenever the support force under you changes—hitting a bump, encountering turbulence, cresting a wave—you feel a change in “g.”

Common Sources Across Different Contexts

Vertical accelerations arise in many fields. The following list summarizes the main physical drivers in a cross-domain view so you can map causes to your situation, whether you’re flying, driving, at sea, or analyzing structures.

• Gravity and support-force changes: Weight is constant at a location, but the support (lift, normal force) can vary quickly, causing upward or downward acceleration (e.g., bumps, roller-coaster crests, aircraft pull-ups).
• Pressure gradients in fluids: Uneven air or water pressure, including gusts, convection, or wave crests/troughs, imparts vertical motion.
• Buoyancy fluctuations: Changes in density (thermals, downdrafts, cavitation) alter buoyant force and vertical motion of balloons, gliders, and vessels.
• Thrust vectoring: Redirecting propulsion (rockets, VTOL aircraft, drones) introduces vertical force components.
• Geometric/trajectory effects: Curved paths (loops, hills, banked turns) redistribute forces, changing the load factor and perceived “g.”
• Ground motion: Earthquakes and blasting generate vertical ground accelerations transmitted into buildings and vehicles.
• Mechanical transients: Starts/stops in elevators, cranes, presses, or machinery produce short, sharp vertical accelerations.
• Wave–structure interaction: Ships and offshore platforms pitch and heave as waves pass, producing cyclic vertical accelerations.

While the mechanisms differ, the unifying idea is a changing balance between gravity and opposing forces; whenever that balance shifts, vertical acceleration follows.

Aviation and the Atmosphere

In flight, vertical acceleration (often felt as “g-load”) primarily reflects changes in lift relative to weight, plus vertical wind motions. Pilots control it with pitch and bank; the environment changes it with turbulence and waves in the air.

Where aviation vertical accelerations come from

The list below outlines the dominant atmospheric and operational sources that cause aircraft to “jolt” up or down.

• Convective turbulence: Updrafts and downdrafts in storms and towering cumulus produce strong vertical motions; microbursts can cause abrupt negative then positive g.
• Clear-air turbulence (CAT): Shear near the jet stream creates turbulent layers with invisible vertical gusts; research has documented increases in CAT intensity and frequency over busy routes since the late 20th century.
• Mountain waves and rotors: Stable air flowing over terrain oscillates, generating powerful vertical waves downwind that can extend well above ridgelines.
• Wake turbulence: Wingtip vortices from heavy aircraft induce vertical components that can upset trailing planes, especially near runways.
• Pilot maneuvers: Pull-ups, push-overs, and banked turns alter lift; load factor n rises above 1 g in pull-ups/turns and drops below 1 g in push-overs.
• Gust fronts and frontal passages: Sharp changes in wind and pressure tilt and lift the airplane abruptly.

The practical implication is that both weather and maneuvering dictate vertical accelerations aloft; staying belted, heeding advisories, and strategic routing help manage the risk.

Trends and safety context

Evidence indicates clear-air turbulence has increased over major routes in recent decades as upper-level wind shear strengthens with climate change. For example, analyses of North Atlantic data (late 1970s–2020) show a notable rise in moderate to severe CAT, and recent high-profile incidents underscore the hazard. Operators respond with better detection (satellite, lidar research), probabilistic forecasts, and avoidance tactics, but the underlying drivers—jet-stream variability and thermal gradients—remain influential.

Road, Rail, and Everyday Experiences

On the ground, you feel vertical accelerations whenever the normal force changes quickly—crossing a speed bump, hitting a pothole, or cresting a hill. Vehicle suspensions, tire compliance, and speed govern the magnitude and duration. Standards such as ISO 2631 address acceptable whole-body vibration levels for comfort and health. Elevators limit “jerk” (the rate of change of acceleration) using S-curve motion profiles to keep rides smooth and safe.

Earthquakes and Structures

Earthquakes impose both horizontal and vertical ground accelerations. Vertical components, while often lower than horizontal, can be comparable or even exceed them near the source or in certain site conditions. This matters for short-span structures, piping, and connections sensitive to uplift. Modern building codes consider vertical-to-horizontal (V/H) ratios, and engineers use base isolation, ductile detailing, and tuned mass dampers to control resultant motions.

Oceans, Ships, and Offshore Platforms

Waves create cyclic pressure fields that lift and drop hulls, producing heave (vertical translation) and pitch/roll coupling. Sea-state, hull form, heading, and speed determine accelerations; naval architects use seakeeping analysis and active fins to reduce vertical motions that drive seasickness and slamming loads.

Measurement and Mitigation

Whether for safety, comfort, or performance, industries monitor vertical accelerations and employ targeted mitigations. The following list summarizes common tools and tactics.

• Sensors: IMUs and accelerometers (in aircraft, vehicles, smartphones) quantify g-loads; barometers and GNSS complement vertical state estimates.
• Forecasting and avoidance: Turbulence models, PIREPs, and satellite/radar imagery guide pilots around convective cells and mountain-wave hot spots.
• Design controls: Suspension tuning, shock absorbers, hull forms, and structural damping limit transmitted accelerations.
• Operational procedures: Speed reductions in rough air or seas, seat-belt policies, and careful routing lower exposure to peaks.
• Motion planning: Elevators, cranes, and robots use jerk-limited profiles to avoid abrupt vertical transients.

Together, measurement and smart design reduce both the frequency and severity of problematic vertical accelerations without sacrificing performance.

Key Takeaway

If the upward forces that balance gravity rise or fall—even briefly—your vertical acceleration changes. From turbulence to earthquakes, bumps to waves, the story is the same: shifting forces in the vertical direction drive the motion you feel.

Summary

Vertical accelerations are caused by net vertical forces, primarily gravity offset by changing lift, normal force, buoyancy, thrust, and pressure gradients. In aviation, they stem from turbulence, waves, wake, and maneuvers; on land, from terrain and mechanical transients; at sea, from waves; and in structures, from seismic motion. Measuring with accelerometers, forecasting environmental drivers, and designing with damping, isolation, and jerk control help manage their impacts on safety and comfort.

Why does vertical velocity increase?

During the downward flight of the projectile, vertical velocity increases due to the effect of gravity. The initial velocity (Vi) of a projectile, released at an angle to the horizontal, has both horizontal (Vh) and vertical (Vv) components.

What causes vertical acceleration?

As long as the net force is acting on an object it will accelerate, or an object will only accelerate because there’s a net force on it. What is the cause of acceleration for an object displaying Vertical Velocity? The answer is gravity pulling it down toward the center of the Earth.

What causes the vertical motion of a projectile?

The vertical motion of a projectile is controlled by the force of gravity.

What has the greatest vertical acceleration?

The Planck acceleration is the absolute limiting acceleration based on the known laws of physics.