Why is the weather forecast all thunderstorm, and there is no thunderstorm?

Thundershower is a weather phenomenon, which is characterized by large-scale cloud movement, much more violent than shower, accompanied by discharge, and is common in summer. Omen phenomenon

When a thunderstorm comes, there are often strong winds and thunderstorms. The wind came, flying sand and stones, the roof was overturned and the wall was blown down. In the storm, things in the street danced with the wind, flying everywhere and even uprooting trees!

Analysis of reasons

In summer, direct sunlight makes the water on the ground evaporate faster than in winter, spring and autumn. The air close to the ground can receive more water vapor because of its high temperature, which leads to the decrease of air density, the lightening of air and the rising of the lightened air. With the increase of altitude, the temperature will gradually drop (every thunderstorm rises 100 meters, and the temperature drops by 0.6 degrees), and the air will gradually cool down. When the air is cool, it can't hold the original abundant water vapor. Some water vapor will condense into small water droplets, and the sky will be cloudy. So, why don't these little drops fall down quickly and turn into rain? This is because the water droplets are too small, and the rising hot air lifts them up and pushes the suspended water droplets higher and higher. Clouds are getting bigger and higher. This kind of cloud is called cumulonimbus cloud in meteorology, and its bottom is about 1000 meters above the ground.

When the small water droplets in the cumulonimbus cloud constantly collide and merge into larger water droplets, they begin to fall, while the hot air rising from the ground keeps rushing upwards, and the friction between them is charged. Thunderstorm weather signs: the rising airflow is positively charged and the falling water droplets are negatively charged. With the passage of time, a large number of positive charges have accumulated at the top of cumulonimbus clouds, while many negative charges have accumulated at the bottom. Due to the negative charge at the bottom of cumulonimbus clouds, the ground is also positively charged.

The water droplets in the cloud merge and increase until the rising hot air can't hold it, and then fall straight from the cloud. The hot air at the lower level was drenched by rain and suddenly became cold. Instead of rushing up, it turned to the ground. At this point, the charge in the air began to discharge, accompanied by thunderous thunder. Because lightning travels at a speed of 300,000 km/s and thunder travels at a speed of 33 1 m/s, people first see lightning and then hear thunder. Sometimes the thunder drags on for a long time, which is caused by the thunder reflected back and forth from clouds, peaks and ground.

Distribution characteristics

In China, thunderstorms mostly occur in hot, humid and bad weather from May to August. Spring and autumn mainly occur in Jiangnan, with the least in winter. /kloc-after 0/0, there were thunderstorms in the vast area north of the Yangtze River.

Judging from the time of day, it mostly happens in the afternoon and evening.

General knowledge of security

1. When there is a thunderstorm and lightning, don't call and answer the phone, but unplug the telephone line. The mobile phone can be used normally! But generally try not to answer the phone outdoors or indoors near the window.

2. Don't turn on the TV, computer, VCD player, etc. Unplug all power plugs during thunderstorms and lightning to avoid personal injury and electrical damage.

3, don't stand under the light bulb, don't take a shower.

4. Try not to go out. If you have to go out, you'd better wear rubber shoes and a raincoat, which can keep out lightning.

5. Try not to open the door or open the window to prevent lightning from hitting the room directly.

6. Don't stick your head and hands out of the window when you encounter lightning in the car.

7. Stay away from trees during a thunderstorm. Try not to run in big strides. You can choose buildings to shelter from the rain. You can also take shelter from the rain in the car, because the car belongs to the metal shell, so people will not be hurt by inductive lightning, nor will they be directly hit by lightning.

8. Don't connect the wires for drying clothes and bedding to the doors and windows.

9. Don't wear wet clothes, hats, shoes, etc. Walking in a thunderstorm. For sudden lightning, the height should be lowered immediately, and the feet should be close together to reduce the harm caused by the step voltage.

10, when lightning strikes, don't get close to all power facilities, such as high-voltage line transformers.

1 1, immediately stop outdoor swimming, boating, fishing and other water activities.

12. If many people gather outdoors, don't crowd each other to prevent power from being transmitted to each other after being struck by lightning.