ST. LOUIS — A viewer recently called the station to ask about a video he saw on TikTok. It intermittently shows some odd shapes in the radar. You may have seen these on-air too. Some content creators on social media are making some wild claims about them.

American Meteorological Society certified meteorologist Chris Higgins says that there is a rather mundane explanation. He says the “pulsing” has to do with the ground clutter that becomes more visible when there is a low level temperature inversion and very humid air. This is most noticeable from the evening into the overnight hours, when the night time inversion sets in. It goes away when the sun heats up the atmosphere and the inversion lifts due to turbulent mixing and incoming solar radiation.

Higgins says that the “spiky stuff” you see on the radar is most common in the mountains because of beam blockage by hills, mountains, and broadcast towers. Meteorologists can also track migrating birds on radar.

“When rain moves away from a radar site, it is put in ‘clear-air-mode.’  Simply put, it is a very sensitive mode that can pick up fields of insects, flocks of birds, pockets of moisture and dust.  These radar returns show up as faint circles around each radar site.  When rain moves into the site’s detection range, the radar is taken out of clear-air mode and put in regular reflectivity mode,” states meteorologist John Fuller.

Doppler radar is essential for tracking storms and weather patterns. The National Weather Service says that the colors on the radar represent reflectivity data. They are the amount of power returned to the radar by objects, measured in decibels.

Bright colors indicate heavy precipitation from large raindrops, hailstones, or snowflakes. An example shows heavy precipitation in red and lighter in blue and green. Brightening colors over time signify strengthening thunderstorms.