--- title: Weather signs and the 30-30 rule — a lesson of Mova's school · trees and pragmatics description: «Weather signs and the 30-30 rule», a lesson of the everyday course of Mova's primary school, sentence by sentence with dependency trees and pragmatics. It begins: Weather often warns you before it turns dangerous: tall dark clouds, a darkening sky, a sudden cool wind and distant rumbles. --- [Mova](https://md.mova.elamur.ai/free/en/) · [this page in HTML](https://mova.elamur.ai/free/en/corpora/school/everyday/15-weather-signs/) [home](https://md.mova.elamur.ai/free/en/) / [corpora](https://md.mova.elamur.ai/free/en/corpora/) / [school](https://md.mova.elamur.ai/free/en/corpora/school/) / [Everyday](https://md.mova.elamur.ai/free/en/corpora/school/everyday/) / Weather signs and the 30-30 rule # Weather signs and the 30-30 rule Lesson 15 of the everyday course of Mova's primary school: 21 sentences, each with its syntax tree and pragmatics. The lessons are written for Mova, and their agreed trees are part of Mova corpus 0.4 (CC BY-SA 4.0). How Mova does on its tests: [the lesson at school](https://md.mova.elamur.ai/free/en/school-run/everyday/15-weather-signs/). - [0](https://md.mova.elamur.ai/free/en/corpora/school/everyday/15-weather-signs/0/) — Weather often warns you before it turns dangerous: tall dark clouds, a darkening sky, a sudden cool wind and distant rumbles. - [1](https://md.mova.elamur.ai/free/en/corpora/school/everyday/15-weather-signs/1/) — Lightning is a giant electric spark; thunder is the sound of the air around it heated so fast that it bursts outward. - [2](https://md.mova.elamur.ai/free/en/corpora/school/everyday/15-weather-signs/2/) — Light reaches you almost instantly, but sound travels only about 1 kilometre in 3 seconds (about 1 mile in 5 seconds), so counting from flash to bang tells you how far away the lightning is. - [3](https://md.mova.elamur.ai/free/en/corpora/school/everyday/15-weather-signs/3/) — The 30-30 rule: if thunder comes 30 seconds or less after the flash, go inside now, and wait 30 minutes after the last thunder before going out. - [4](https://md.mova.elamur.ai/free/en/corpora/school/everyday/15-weather-signs/4/) — Today experts say even more simply: when thunder roars, go indoors. - [5](https://md.mova.elamur.ai/free/en/corpora/school/everyday/15-weather-signs/5/) — Example: on a beach in Florida, a boy counts 12 seconds from flash to bang — the lightning is about 4 kilometres away, close enough to strike, so his family leaves the beach. - [6](https://md.mova.elamur.ai/free/en/corpora/school/everyday/15-weather-signs/6/) — A family in Colorado kept hiking up a peak when they heard thunder; lightning struck nearby and knocked a man in their group to the ground, and he needed hospital care. - [7](https://md.mova.elamur.ai/free/en/corpora/school/everyday/15-weather-signs/7/) — A boy in Florida kept swimming in a lake while dark clouds rolled in; lightning hit the water nearby, and lifeguards cleared the lake just in time. - [8](https://md.mova.elamur.ai/free/en/corpora/school/everyday/15-weather-signs/8/) — Tall, dark, towering thunderclouds can bring lightning, heavy rain, hail and strong wind. - [9](https://md.mova.elamur.ai/free/en/corpora/school/everyday/15-weather-signs/9/) — A sudden cool gust of wind often comes just before a thunderstorm arrives. - [10](https://md.mova.elamur.ai/free/en/corpora/school/everyday/15-weather-signs/10/) — Thunder is the sound of air suddenly heated by lightning and expanding very fast. - [11](https://md.mova.elamur.ai/free/en/corpora/school/everyday/15-weather-signs/11/) — Light travels so fast that you see lightning almost the moment it happens. - [12](https://md.mova.elamur.ai/free/en/corpora/school/everyday/15-weather-signs/12/) — Sound travels about 1 kilometre in 3 seconds, or about 1 mile in 5 seconds. - [13](https://md.mova.elamur.ai/free/en/corpora/school/everyday/15-weather-signs/13/) — If thunder comes 30 seconds or less after a flash, go inside a building or a hard-topped car. - [14](https://md.mova.elamur.ai/free/en/corpora/school/everyday/15-weather-signs/14/) — Wait 30 minutes after the last thunder before going back outside. - [15](https://md.mova.elamur.ai/free/en/corpora/school/everyday/15-weather-signs/15/) — A tall lone tree is a dangerous place to shelter, because lightning often strikes tall objects. - [16](https://md.mova.elamur.ai/free/en/corpora/school/everyday/15-weather-signs/16/) — A hard-topped metal car protects you because its metal body carries the lightning around you; the rubber tyres do not. - [17](https://md.mova.elamur.ai/free/en/corpora/school/everyday/15-weather-signs/17/) — Lightning can strike the same place more than once; tall towers are struck many times a year. - [18](https://md.mova.elamur.ai/free/en/corpora/school/everyday/15-weather-signs/18/) — Never walk or drive into flood water: fast water only 15 centimetres (6 inches) deep can knock a person over. - [19](https://md.mova.elamur.ai/free/en/corpora/school/everyday/15-weather-signs/19/) — Lightning can strike more than 10 miles (about 16 kilometres) away from the storm that makes it, even where it is still sunny. - [20](https://md.mova.elamur.ai/free/en/corpora/school/everyday/15-weather-signs/20/) — Lightning kills people every year, most of them outdoors near water, on high ground or under tall trees. - ← previous: [Reading faces and voices](https://md.mova.elamur.ai/free/en/corpora/school/everyday/14-faces-and-voices/) - next →: [Finding your way with landmarks](https://md.mova.elamur.ai/free/en/corpora/school/everyday/16-landmarks/) - ↑ back to [Everyday](https://md.mova.elamur.ai/free/en/corpora/school/everyday/)