Radar sometimes detects things that aren’t rain. Bats, birds, and bugs sometimes fly in such numbers that modern radar systems detect the reflections from these creatures. Non-biological things, such as wind turbines in wind farms, also sometimes cause radar to register returned signals.
Big storms start small. Tropical cyclone Idai in the Indian Ocean, typhoon Hagibis in the Pacific Ocean, and hurricane Dorian in the Atlantic Ocean all gained energy and organization over time. And while the words vary (e.g., typhoon, hurricane), the term tropical cyclones refers generally to these powerful systems that form over warm ocean water.
When hurricanes and other dangerous weather events happen, weather forecasters warn people of the potential danger. Fortunately, we also have access to many of the images and data that meteorologists, public officials, and emergency managers rely on to make decisions.