What does it mean if there is lightning under the cloud in the weather forecast of Apple's mobile phone?

In iphone weather, clouds and lightning mean thunderstorms.

Iphone weather map means: light rain: only one drop of water falls on the cloud; Moderate rain: two drops of water fall from the clouds; Heavy rain: three drops of water fall from the clouds; Heavy rain: four drops of water fall from the clouds; Shower: an inverted triangle with a light rain spot on it.

1. Weather symbol: a special symbol representing various weather phenomena, clouds and sky conditions. Includes weather phenomenon symbols for observation and recording and weather graphic symbols for media communication.

2. When observing a certain weather phenomenon, meteorological observers should record the corresponding symbols in the "Weather Phenomenon" column of the observation record book of the day, except for a few phenomena, and also record the starting and ending time. Based on these symbols, combined with the intensity, coexistence and some characteristics of weather phenomena, a group of symbols that can be filled in weather maps are called cartographic symbols.