Typhoon warning signal:
1, typhoon blue warning signal
It may or has been affected by tropical cyclones within 24 hours, and the average wind force along the coast or land is above 6, or the gust is above 8 and may continue.
2. Typhoon yellow warning signal
It may or has been affected by tropical cyclones within 24 hours, and the average wind force along the coast or land is above 8, or the gust is above 10 and may continue.
3. Typhoon orange warning signal
12 hours may be or has been affected by tropical cyclones, the average coastal or land wind force 10 or gust 12 or above and may continue.
4. Typhoon red warning signal
It may be or has been affected by tropical cyclones within 6 hours, and the average coastal or land wind force is above 12, or the gust is above 14 and may continue.
Causes of typhoon formation:
The formation of typhoon requires the following conditions: the sea surface water temperature is above 26.5℃; Initial disturbance of a positive vorticity; The shear of ambient wind in the vertical direction is very small; Low pressure or cloud disturbance is at least several latitudes from the equator. Because people don't fully understand the formation of typhoons now, the above list is only a necessary condition for the formation of typhoons.
The initial stage of typhoon is tropical depression, and it usually takes about 2 days from the initial low-pressure circulation to the maximum average wind force near the center, only three or four days for the slow one and only a few hours for the fast one. In the development stage, the typhoon continuously absorbs energy until the central air pressure reaches the lowest value and the wind speed reaches the maximum value.
After the typhoon landed, under the joint influence of ground friction and insufficient energy supply, it will quickly weaken the death.