Plain English Meaning
Fake weather streaks on a radar picture caused by the radar pointing toward the sun. The lines look like weather but are not, so pilots should ignore them when planning around real weather.
Full Definition
False radar returns that appear on a NEXRAD weather display as straight lines or spikes radiating outward from a radar site, caused by the radar antenna detecting electromagnetic energy from the sun when the sun aligns with the antenna's scanning beam at sunrise or sunset. They are a known display artifact, not actual precipitation or weather.
Context Anchor
Seen when reading NEXRAD weather on an electronic flight display or multi-function display, especially in discussions of NEXRAD display errors and abnormalities.