What happened to the weather before it rained?

Generally, before the rain comes, the air humidity will increase greatly and the air pressure will drop significantly.

Since ancient times, people are familiar with the warning signals before rain, such as frogs chirping and swallows flying low, with high accuracy. There are several others:

Ants crossing the road-ants digging holes in the ground think that the holes will be flooded when it rains, that is, they will run away before it rains.

Earthworms come out of the hole-the ground is wet and soft, and earthworms will climb out of the ground, which indicates that it will rain.

Other signs before rain are swarms of mosquitoes and rain ants.

Swallow low flying snake aisle

The heavy rain is coming soon!

In summer, if you see frogs gathering by the pond, it means it will rain.

Dragonflies also fly low, fish jump out of the water, earthworms and snakes climb out of holes, the ground ebbs, there are water drops on stones, frogs croak hoarsely, and people with tinea manus and pedis can afford blisters.

For thousands of years, the working people in our country have summed up the rich experience of "knowing the sky by observing the clouds" according to the changes in the shape, direction, moving speed, thickness and color of clouds in production practice, and compiled these experiences into proverbs. Here, we will summarize these proverbs about "knowing the weather from the clouds", and interested friends may wish to make some observations and comparisons.

"Hook clouds in the sky, rain drops on the ground": Hook clouds are called hook clouds in meteorology and generally appear in front of warm fronts and low pressure. The appearance of hook cloud indicates that a front or low pressure is coming, which is a precursor of rain drop. However, after rain or winter, it will appear sunny or frosty continuously, so there are sayings that "the hook cloud dissipates, and the sunny day is drier" and "the hook cloud dries up in winter".

"battery cloud, rain": battery cloud refers to fort-shaped altocumulus or fort-shaped stratocumulus, which mostly appears in front of the trough of low pressure, indicating that the air is unstable, and thunderstorms usually come every 8 ~ 10 hours.

"Clouds pass through clouds, and it rains": Clouds passing through clouds means that the moving directions of the upper and lower clouds are inconsistent, that is to say, the heights and winds of clouds are inconsistent, and they often appear near the front or low pressure, so it indicates rain. Sometimes the wind direction of the cloud is opposite to the ground, and there is a saying that "the sky changes when the cloud goes against the wind".

"The river pig crosses the river, and it rains heavily": The river pig refers to the broken rain clouds in the nimbostratus. The appearance of this cloud indicates that there is a lot of water vapor in nimbostratus, and a rainstorm is coming. Sometimes, the broken rain clouds are blown to cloudless places by strong winds, and at night, the clouds like river pigs float across the "Galaxy", which is also a precursor to rain.

"Cotton cloud, rain is coming": Cotton cloud refers to flocculent cumulus clouds, indicating that the middle atmosphere is very unstable. If there is enough water vapor in the air and there is upward movement, cumulonimbus clouds will form and thunderstorms will come.

"Gray cloth hangs over the sky, and the rain will continue": Gray cloth cloud refers to nimbostratus, which is mostly formed by thickening and metamorphosing high-level clouds, with a large and thick range, and sufficient water vapor in the clouds, which often produces continuous precipitation.

"Cloud to the east, chariots and horses to; The clouds go south and the water rises; Clouds to the west, covered with hemp fiber; Clouds going north are good for drying wheat ":according to the moving direction of clouds, it is predicted that the weather will be fine, and the clouds will move east and north, indicating that the weather will be fine;" "The movement of clouds to the west and south indicates that it is going to rain. The moving direction of a cloud generally indicates the wind direction at its height. This proverb describes the distribution of clouds in different places of low pressure. Suitable for dense, low and fast moving clouds all day.

"Dark clouds catch the sunset, but today and tomorrow will not fall": When the sun goes down, a wall-like dark cloud rises under the western horizon to catch the sun, indicating that the dark clouds move eastward, and the rainy weather in the west is moving and it is going to rain. Generally speaking, if the clouds catch up, it will rain that night; If it is connected with the high clouds, it will rain the next day. However, if the dark clouds in the west are lumpy or discontinuous, or some areas are cloudy, it is not a sign of rain in the future.

"The northwest sky is unlocked, and the sun shines brightly": On rainy days, the clouds in the northwest crack and reveal a blue sky, which is called "the sky is unlocked". This shows that the local area is at the back of the rainy weather system. As the rainfall system moved eastward, the rain stopped and the weather improved.

"Now the sun appears, but it hasn't been seen for three days": in spring and summer, at noon on rainy days, the clouds split and the sun appeared, but the clouds quickly gathered and became thicker, indicating that the local area was affected by the quasi-static front, and the airflow near the quasi-static front rose strongly and changed greatly. When the updraft increases, the clouds become thicker and the rainfall increases. When the updraft weakens, the clouds become thinner and the rainfall decreases or stops; Around noon, the sun shines strongly, the upper part of the cloud is heated and evaporated, or the updraft below the cloud weakens, and the zenith cloud will split. As the sun's exposure decreases, or the updraft under the clouds strengthens, the divided clouds will gather again and become thicker. So "the sun appears now" often indicates that it will continue to rain. This proverb is similar to such proverbs as "the sun smiles, the temples are drenched" and "Yi Deng takes a photo, the next foot takes a photo".

"The carp spot in the sky doesn't need to be turned over by the sun tomorrow": the carp spot refers to translucent cumulus clouds. The air mass that produces this cloud is stable. In the evening, when encountering downdraft, the clouds quickly dissipated, and the weather was fine the next day. However, if the cloud looks like a tiny fish scale, it is cirrocumulus. This kind of cloud mostly appears in front of the trough of low pressure or around the typhoon, and there will be wind or rain in the near future.

"The clouds are heading east, blowing gusts; Clouds go west, covered with hemp fiber ":The cloud here refers to the low cloud in the low-pressure area. The low pressure is from west to east (in fact, it often moves from southwest to northeast). The cloud goes west, indicating that this place is in front of the low pressure, because it will rain locally; The cloud is moving eastward, indicating that the low pressure has moved past the local area, and the local area is behind the low pressure. The weather is going to clear up, and a strong wind often blows before it clears up.

"Where the cloud hook goes, the wind comes": The cloud hook refers to the tail of the hooked cloud, which appears in the sky. Sometimes there are small hooks at the top, and some are in rows. The small hook at the top refers to the direction of the high-altitude wind, which is often associated with the ground, so the direction of the cloud hook can generally tell the direction of the wind.

"Dark clouds cover the morning, and the wind will come even if it doesn't rain": It means that there are dark clouds covering the sun in the southeast in the morning, which indicates rain. Because the warm and humid southeast wind blows in the morning, the temperature is higher than the local air, and the water vapor is easy to rise into clouds. In addition, during the day, the ground is heated, and the air convection rises, which further promotes the clouds to rise, and the water vapor turns into water droplets when it is cold, which may make it windless and rainy.

"Huang Yun has turned upside down, and it is going to lay ice eggs": Huang Yun is mostly caused by the strong rise of warm and humid airflow, and there are often showers and hail.

"When the mountain wears a hat, it rains heavily": When the mountain wears a hat, it shows that the air pressure is low, and most of the water vapor in the air forms clouds at the top of the mountain. As for whether it will rain, it generally depends. If the clouds gradually decrease and thicken, it is more likely to rain. On the contrary, if the clouds gradually rise and become thinner, it is less likely to rain.

"Clouds eat under fog, fog eats clouds": After seeing fog, clouds come, which may indicate that low pressure is coming, which is a sign of rain. On the contrary, if the clouds clear up, it means that the low pressure has passed and sunny weather is coming.

"Sunset shines at the foot, and the rain falls within three days": it means that the sun shines through the cracks in the clouds, which is called "the sun shines at the foot". It appears in the evening, indicating strong convection and indicating rain.

"Don't go out in the morning and take Wan Li Road at night": There are no clouds in the east and clouds in the west in the morning. Sunlight shines on the clouds and scatters rosy clouds, indicating that there is a lot of water vapor in the air or a rainfall system moves in. During the day, the air is generally unstable and the weather will turn rainy. If there is a sunset glow at night, it means that the sky in the west has cleared up, and the general convection is weakened at night. The clouds forming rosy clouds in the east will move eastward or tend to dissipate, saying that it will be fine tomorrow.

"Long sunny, foggy and cloudy, long cloudy and foggy and sunny": refers to the appearance of fog after a long sunny day, indicating that the warm and humid airflow moves and the air is humid, which is a sign of cloudy and rainy; Fog appears after a long cloudy day, indicating that the clouds in the sky become thinner, split and dissipate, and the ground temperature drops, so that water vapor condenses into radiation fog. When the fog disappears after sunrise, there will be sunny days.

In the morning of warm season, if castle clouds appear on the horizon, it means that the humid atmosphere at this height is already very unstable. At noon, once the low-level convection develops and the unstable layer merges, it will produce strong convective movement, form cumulonimbus clouds and cause thunderstorms. So there is a proverb "pagoda clouds in the morning, and it rains cats and dogs in the afternoon".

In addition, clouds with weather omen often have certain continuity, seasonality and locality in the evolution process. Clouds in the sky move from a distance in the order of cirrus, cirrostratus, stratus and nimbostratus, and gradually change from less to more, from high to low, from thin to thick, indicating that rainy weather is coming; On the contrary, if the clouds change from low to high, from thick to thin, and from layered clouds to scattered clouds, there will be no rainy weather. In the morning of warm season, if there are flat, convex and isolated clouds (light cumulus clouds) or fast-moving white broken clouds (broken cumulus clouds) in the sky, it means that the air in the middle and lower layers is relatively stable and the weather is fine.

In addition, the color of clouds can also indicate some kind of weather. For example, the color of hail cloud is first white and then black, and then red appears in the cloud, forming a white, black and red distorted cloud with khaki edges. Black is caused by the sun's inability to penetrate clouds; White is the result of non-selective scattering or reflection of sunlight by clouds; Red and yellow are the phenomena that some cloud droplets (ranging from one thousandth to one hundredth of a millimeter in diameter) selectively scatter sunlight. Sometimes rain clouds are pale yellow, but the color of the clouds is uniform and will not stir. There are also many proverbs that hail comes from the color and shape of clouds. For example, there is a proverb in Inner Mongolia, such as "If you are not afraid of dark clouds, you are afraid of dark clouds and red clouds, and you are most afraid of white worms in Huang Yun". Stir clouds and hail in groups; There are proverbs such as "When clouds fight, hail will fall", "Huang Yun has red dark clouds, and the clouds toss and turn, and there are many hail disasters", and there are also sayings such as "In the afternoon, the dark clouds roll into a ball, and the wind, rain and hail come together" and "The sky is yellow and sultry, and the rivers roar to prevent ice eggs", all of which show that when the air convection is strong, the clouds develop rapidly and roll up and down like smoke.

It is yellow, and the water overflows the wall.