The phrase "constantly appearing" is correct and can be used in written English.
You can use it to describe a persistent or recurring occurrence or situation. For example, "The warning signs were constantly appearing, but he chose to ignore them."
New applications of telemetry are constantly appearing, particularly in the fields of research and scientific investigation.
This is a distinctly European capital, with many venerable restaurants and constantly appearing newcomers.
Quantum mechanics dictates that particles of matter and anti-matter are constantly appearing and disappearing across the universe.
"Constantly appearing in court and defending the right to report or express an opinion amounts to obstruction of professional activities".
Macabre-looking characters are constantly appearing behind Nurse Kathy unannounced, an event invariably accompanied by overstated musical cues.
Now that his work was constantly appearing in international festivals, I asked him who he was making it for.
It constantly appears in ads for houses with Palladian windows.
He constantly appears to be focused on what is in front of him, recognizing how fragile success can be.
Even though individual plants live only three or four years, C. coum self-seeds prolifically, so new ones constantly appear.
Furthermore, the images are taken outdoors with variable light conditions, so shadows and reflections constantly appear and disappear as the car moves, interfering with the optical flow calculation.
Depending on the surface index, there appeared a clear difference in size and density between the indices, and this trend constantly appeared throughout the Ta range as clearly shown in Figure 4.
