Many local signs (including astronomical phenomena and physical phenomena) can, to a certain extent, indicate whether the typhoon affects the local area. These signs are the experience accumulated by the working people of our country in dealing with "God" for thousands of years, and can be used as a supplement to the typhoon forecast of the meteorological station. People often observe and study:
(1) Long wave: also called swell. When the typhoon is still far away from the sea, a special wave can be seen from the center of the typhoon at the seaside. The top of the wave is round, and the wave head is not high (usually only one or two meters high). The distance between the wave head and the wave head is relatively long, which is different from ordinary sharp top and short distance waves. Long waves look round, sound heavy, and beat slowly, spreading about 70-80 kilometers per hour. When this kind of wave is close to the coast, it will turn into rolling surf, which often makes the water level of the coast rise and the waves surge. When you see this scene on the coast, and with the passage of time, the long waves become more and more fierce, this omen typhoon is moving towards you.
(2) Sea roar: Sea roar is also called sea sound or sea roar. Two or three days before the typhoon, sea roar can also be heard along the coast. Its buzzing sound is like the sound of an airplane in the distance, or like the horn of a conch or the circling of a distant thunder. It is especially clear and loud at night. When the sound gradually increases, it indicates that the typhoon has gradually approached; If the sound weakens, it indicates that the typhoon is leaving. There is a cave facing the sea in Zhoushan Islands, Zhejiang Province. A few days before the typhoon, there will be sea noise. Fishermen took typhoon prevention measures based on this omen, and the effect was good.
(3) Taimu: This is a kind of experience of Fujian and other coastal fishermen in surveying the observatory based on the sky phenomenon. When the center of the typhoon is about five or six hundred kilometers away from the coast, coastal fishermen can see that the eastern sky is dotted with bright clouds like tangled threads, which spread like fans from the horizon (this is called convergence cirrus in meteorology), about six or seven kilometers high, and beautiful clouds will appear in the sky in the morning or evening. The masses call it "Taimu", which means that when they see such clouds, a typhoon will come.
(4) Wind cable: coastal fishermen are used to calling the light line in the sky, that is, three or five blue stripes radiating upward from the eastern horizon across the sky, (wind cable). This is because there are many towering convective cloud bands in the typhoon area. When the typhoon approaches, the sun will appear dark blue stripes in the sky, sometimes it will cross the sky, converge in the opposite direction of the sun, and disappear quickly as the sun rises. Therefore, seeing the "wind cable" is also a sign of the impending typhoon.
(5) Broken rainbow: There is a saying among the fishermen along the coast of Fujian and Guangdong that "when the rainbow is broken, the sky will change". This "weather change" means that the typhoon will attack and bring heavy rain. Broken rainbow, also called short rainbow, is a half rainbow that appears on the southeast sea. It does not have the solitary bend of the common rainbow, and its color is not bright. It usually appears at dusk. Because the broken rainbow is formed because the water drops in the low air around the typhoon refract sunlight, seeing the broken rainbow indicates that the typhoon is coming.
(6) Wind direction: "one bucket of east wind and three buckets of rain", "north wind in June, water soaked chicken coop" and other experience of watching the wind report typhoon are spreading among fishermen. In the proverb, "Three Dou Rain" and "Chicken Cage Soaked in Water" refer to the wind and rain on Taiwan. This is because typhoons mostly come from the vast ocean in the southeast. When a place is affected by the peripheral air flow in the first half circle of the typhoon, the wind directions in the west, north and east often appear, and it will last for half a day to more than one day, which is the omen of the typhoon. This is also the meaning of the proverb "When the east wind turns to the north, tie the rope and tie the house". However, sometimes before the typhoon comes, there is almost calm wind in some places. The sea surface is as calm as a mirror, and the moon shadow is clearly reflected in the sea. Therefore, the experience of "the sea bottom shines on the moon and the strong wind prevails" is also spread among the people. This gale is also caused by typhoon.
(7) Jellyfish: Jellyfish are one of the marine creatures that can hear the infrasound waves generated between typhoons and waves. Infrasound waves with a frequency of 8-13 Hz hit a small listening stone in the jellyfish "ear" (a small ball on a thin handle); The otolith stimulates the nerve receptors in the wall of the "ball". In this way, the jellyfish could vaguely hear the roar of the coming typhoon, so they left the bank and swam to the sea to avoid being crushed by the strong wind and waves. The predictor, which simulates the characteristics of jellyfish, consists of a horn, a resonator that receives infrasound waves, a piezoelectric converter that converts vibration into electrical pulses, and an indicator. Install this set of instruments and equipment on the ship deck, rotate the horn 360 degrees, and when the rotation stops, the direction pointed by the horn is the direction of the typhoon; The indicator shows the intensity of the storm brought by the typhoon.
(8) Hydrogen balloon: Fishermen also use hydrogen balloons to measure typhoons. That is, put a balloon filled with hydrogen (about 50 cm in diameter) beside your ear and listen, you can know whether there is a typhoon in the distance and whether it will attack the local area. What is the reason? Because the friction and impact between the peaks of strong wind and huge waves will form a low-frequency sound wave with a frequency of 8-13 Hz per second. This kind of sound wave is faster than the propagation speed of wind waves. Although the human ear cannot hear it directly, the balloon filled with hydrogen can resonate with the low sound wave and produce a vibration. The amplitude and intensity of this vibration will give a pressure to the eardrum of people close to the hydrogen balloon, making the eardrum produce a sense of vibration. The closer the typhoon is, the clearer the feeling will be. According to the change of clarity, we can judge whether the typhoon is approaching or far away.
(9) Sea fire: Two or three days before the typhoon, you can see the phosphorescence in spots and patches on the surface of the sea water, flashing constantly, sinking and floating. Fishermen call it "sea fire" or "floating sea lamp". In fact, this is the scene that some luminous plankton, such as noctiluca, hornwort, phosphorus bacteria, krill, etc., and some fish with phosphorus bacteria, float on the surface of the sea. Some fish, especially those in shallow waters, will float when the typhoon approaches, and some larger fish, such as dolphins, tend to flock to the sea surface. Deep sea fish also come to the shallow sea with the current, and even whales can be seen. Sometimes, some deep-sea fish and benthos can be found floating up, such as sea snakes floating on the surface of the sea.
(10) The phenomenon of fish floating up: it is mainly because the wind and waves of typhoon drive them to gather near the sea, or the low-frequency storm sound wave is inaudible to human ears, but some fish and shrimp in the sea can feel it, so they are frightened and agitated and flee in all directions; Or because the air pressure in the typhoon area drops significantly, the oxygen content in the sea water decreases, and the fish will float up. It is said that some marine creatures like to breed in this weather condition, so they float on the sea. Of course, the turbid sea water and the rolling sediment are the reasons for the floating of shallow sea fish and benthos.
Before the typhoon, you can also see a large group of seabirds flying towards the land in a hurry. Sometimes the birds are so tired that they fall on the ship or the sea, and even groups of them will rest on the deck, and they will not leave no matter how you expel them.
