Wikipedia’s page on gravity waves covers the physics behind how a big rocket launch can disturb GPS signals. A gravity wave is a wave in a fluid, or at the boundary between two fluids, where gravity is the force pulling the displaced fluid back toward equilibrium. Ocean swell and wind waves are the familiar kind. Tsunamis, tides and ship wakes are gravity waves too.

The same thing happens in air. Gravity waves form in the troposphere when air flows over mountains or along weather fronts. As they climb into thinner air higher up, their amplitude grows until they break and hand off their momentum to the surrounding flow. That drives large-scale patterns like the Quasi-Biennial Oscillation.

Waves that make it all the way to the ionosphere produce traveling ionospheric disturbances, which radar can pick up. Since GPS signals pass through the ionosphere, a disturbance there shifts the timing and degrades position fixes.…