Sun glitter is a bright, sparkling light formed when sunlight reflects from water waves. A rippled by a locally smooth surface such as water with waves will reflect the sun at different angles at each point on the surface of the waves. As a result, a viewer in the right position will see many small images of the sun, formed by portions of waves that are oriented correctly to reflect the sun’s light to the viewer.
Flat-Earthers take the long shape of the reflection of a sunset on an ocean surface as ‘proof’ that Earth is flat. They are wrong. Sun glitter is the result of rippling water. The difference in curvature between the flat and spherical Earth model is not that far to cause the difference in the shape of sun glitter.
During a sunset, sun glitter will appear as a single long reflection from close to the viewer all the way to the horizon. However, on a closer look, sun glitter consists of many small reflections of the sun; or sun glints.
Flat-Earthers like to devise a “simulation” to show that a curved surface does not result in the shape of reflection similar to reality, and thus, they concluded that “Earth is not a sphere”. Their mistake was to place the observer too far from the surface, and by making far too large of a curvature to represent spherical Earth. Their simulation was more suitable to describe how sunglint —the reflection of the Sun on the smooth ocean surface— appears from space. Pictures of Earth taken from the Himawari-8 satellite, for example, look similar to the characteristic of the reflection on their simulation.
The more appropriate simulation to represent sun glitter is the reflection on a wet road. A road is not perfectly smooth, but a wet one is covered by water that reflects light specularly in many directions. The observer would also be close to the surface, and thus, more similar to what we are trying to simulate. The fact that the road is flat, convex or concave does not change the reflection characteristics by much. Not as much as what these flat-Earthers are showing to us. Furthermore, a road is usually not perfectly flat but slightly curved to allow excess water to run off.