Weather characteristics before the typhoon approaches

Weather characteristics before the arrival of the typhoon: high clouds appear, thunderstorms stop, visibility is good, sea and land winds are not obvious, showers stop and fall, wind direction changes, and special sunset glow.

1. The appearance of high clouds

At the outermost edge of the typhoon are cirrus clouds, white feathery or horsetail-shaped very high clouds. When such clouds appear in a certain direction, they gradually Thickening into denser cirrostratus clouds indicates that a typhoon may be approaching.

2. Thunderstorms stop

In summer, thunderstorms often occur in mountainous and basin areas every afternoon. If the thunderstorm suddenly stops, it means that a typhoon may be approaching.

3. Good visibility

Two or three days before the arrival of the typhoon, the visibility improved and the mountains and trees in the distance could be clearly seen.

4. The sea and land breezes are not obvious

Usually the wind blows from the sea to the land during the day and from the land to the sea at night. It is called sea breeze and land breeze, but before the typhoon is coming, After a few days, this phenomenon will not be obvious.

5. Showers that suddenly stop and fall

When high clouds appear, the clouds gradually become denser and lower, and showers often fall and then stop. This is also a sign of an approaching typhoon.

6. Change of wind direction

The southwesterly wind often blows in summer and is relatively gentle. However, if it changes to the northeasterly wind, it means that the typhoon is approaching and has begun to be affected by the edge of the typhoon. Impact, the wind speed will gradually increase thereafter.

7. Special sunset glow

One or two days before the typhoon strikes, when the sun sets, several beautiful radiating red and blue lights often emit under the western horizon, shooting into the sky. The top then converges to the point where the east is symmetrical with the sun. This phenomenon is called anti-twilight.

Characteristics of typhoons after landing

1. Strong winds

The wind speed of typhoons is mostly above 17 meters/second, or even above 60 meters/second. According to measurements, when the wind reaches level 12, the wind pressure per square meter on a plane perpendicular to the wind direction can reach 230 kilograms. Therefore, the strong winds of typhoons and the waves caused by them can throw a 10,000-ton ship into the air and break it in half, or push the ship inland; it can also damage or even destroy buildings, bridges, vehicles, etc. on land. Especially in areas where buildings are not reinforced, the damage is greater.

2. Heavy rain

When a typhoon lands, the center of the rainfall can drop 100 to 300 mm or even 500 to 800 mm of heavy rain in a day. Floods caused by typhoons and rainstorms are fierce and destructive, and are the most dangerous disasters.

3. Storm surge

When a typhoon moves towards the land, due to the strong winds and low pressure of the typhoon, the sea water accumulates strongly towards the coast, the tide level rises sharply, and the water waves are overwhelming. Pressing towards the coast. The storm surge of a strong typhoon can raise coastal water levels by 5 to 6 meters. If a storm surge meets the high tide level of an astronomical tide, it can produce high-frequency tide levels, causing the tide to overflow and break seawalls, destroying houses and various building facilities, flooding towns and farmland, and causing a large number of casualties and property losses.