How to judge weather changes

"Knowing the Weather by Looking at Clouds"

Long-term observation and practice have shown that the generation and dissipation of clouds and the evolution and transformation of various types of clouds are all based on certain water vapor conditions. and atmospheric movement conditions. People cannot see water vapor, nor can they see atmospheric movement, but from the emergence and evolution of clouds, we can see every move of water vapor and atmospheric movement, and water vapor and atmospheric movement play an extremely important role in weather phenomena such as rain, snow, ice, hail, etc. role. For thousands of years, the working people of our country have summarized a wealth of experience in "looking at the clouds to know the weather" based on changes in the shape, direction, speed, thickness, color, etc. of clouds in production practice, and compiled these experiences into proverbs. .

"There are hook clouds in the sky and rain on the ground": Hook clouds refer to cirrus clouds. Behind these clouds, there are often fronts (especially warm fronts), low pressure or low pressure troughs moving in, which is an omen. The rain is coming.

"Fort clouds, drenched with rain": Fort clouds refer to fort-shaped altocumulus clouds or fort-shaped stratocumulus clouds. They often appear in front of low-pressure troughs, indicating that the air is unstable. Thunderstorms usually occur every 8-10 hours. .

"Clouds crossing clouds, rain dripping": Clouds crossing clouds means that the upper and lower clouds move in different directions, that is to say, the wind direction at the height of the clouds is inconsistent. It often occurs near fronts or low pressure, so it indicates rain. Sometimes the direction of clouds is opposite to that of the wind on the ground, and there is a saying that "when clouds move against the wind, the sky will change."

"When the river pig crosses the river, it rains heavily": The river pig refers to the broken rain clouds under the nimbus clouds. The appearance of such clouds indicates that there is sufficient water vapor in the nimbus layer clouds and heavy rain is coming. Sometimes broken rain clouds are blown by strong winds to cloudless places, and clouds like river pigs are seen floating across the "Milky Way" at night, which is also a precursor to rain.

"Cotton cloud, rain is coming": Cotton cloud refers to flocculent altocumulus clouds. The appearance of this kind of cloud indicates that the middle atmosphere is very unstable. If there is sufficient water vapor in the air and there is upward movement, cumulonimbus clouds will form. , there will be a thunderstorm coming.

"A gray cloth hangs in the sky, and the rain will continue.": Gray cloth clouds refer to nimbostratus clouds. Most of them are formed by the lowering and thickening of altostratus clouds. They are very large and thick, and there is sufficient water vapor in the clouds. They are often Produces continuous rainfall.

"When clouds go to the east, cars and horses can pass; when clouds go to the south, the water swells; when clouds go to the west, it is covered with raincoats; when clouds go to the north, it is good for wheat to dry": predict cloudiness and sunshine based on the direction of cloud movement, Clouds moving east and north indicate fine weather; clouds moving west and south indicate rain is coming. The direction of cloud movement generally indicates the wind direction at its height. This proverb explains the distribution of clouds in different parts of the low pressure. It is suitable for low and fast-moving clouds that are dense throughout the sky.

"Fish-scale sky, even without rain": Fish-scale sky refers to cirrocumulus clouds. The appearance of such clouds indicates that the upper atmosphere is unstable. If the clouds continue to decrease and thicken, it means that the area is already under low pressure. Ahead of the trough, it will soon rain or become windy.

"Carp spots in the sky, there is no need to turn over the grains tomorrow": Carp spots refer to light-transmitting altocumulus clouds, which are often controlled by denatured high-pressure air masses caused by cold warming. If the clouds do not continue to thicken, they will still remain in the short term. sunny.

"Dark clouds catch the setting sun, and if it does not set today, it will set tomorrow": refers to when the sun sets, a dark cloud like a city wall rises under the western horizon to catch the sun, indicating that the dark clouds are moving eastward and the rainy weather system in the west is moving. Come, it's going to rain. Generally speaking, if there are medium clouds, it will rain that night; if there are high clouds, it will rain the next day. However, if the dark clouds in the west appear in strips or disconnected, or the local area is originally cloudy, it is not a sign of rain in the future.

"The sky is locked in the northwest, and the sun is shining brightly in the Ming Dynasty": It refers to the clouds in the northwest split open on rainy days, revealing a piece of blue sky, which is called "the sky is unlocked". This shows that the local area is already at the rear of the rainy weather system. As the rainy system moves eastward, the local rain will stop and the weather will improve.

"The sun appears once and does not see for three days": refers to spring and summer, at noon on a rainy day, the clouds break up and the sun shows its face, but the clouds quickly gather and thicken, which indicates that the local Under the influence of the quasi-stationary front, the airflow near the quasi-stationary front rises and falls strongly and changeably. When the updraft strengthens, the clouds thicken and the rainfall increases; when the updraft weakens, the clouds thin and the rainfall decreases or stops; around noon, when the sun shines strongly, the upper part of the cloud layer is heated and evaporates, or the updraft below the cloud layer weakens and the zenith The clouds will split. As the sun's irradiation weakens, or the updrafts below the clouds strengthen, the clouds that have broken apart gather back together and become thicker. Therefore, "the sun appears" often indicates continued rain. 'This proverb is similar to the proverbs such as "The sun smiles and rains down the temple", "When it shines, it falls down a foot".

"Sunset feet, rain falls within three days": refers to the sun shining down from the gaps in the clouds, called "sunshot feet". The appearance of sunray feet in the evening indicates strong convection and indicates rain.

"The morning glow does not go out, but the sunset glow travels thousands of miles": There are no clouds in the east in the morning, and there are clouds in the west. The sunlight shines on the clouds and scatters colorful clouds, indicating that there is abundant water vapor in the air or a rainy system has moved in, and during the day The air is generally unstable and the weather will turn cloudy and rainy; sunset glow appears in the evening, indicating that the sky in the west has cleared up. In addition, convection generally weakens at night, and the clouds in the east that form colorful clouds will move further east or tend to dissipate, indicating that the sky will be clear. .

"Long-term clear weather, heavy fog and cloudy weather, long-term cloudy weather, heavy fog and clear weather": refers to the appearance of fog after a long-lasting clear sky, indicating that warm and humid air has moved in, and the air is moist, which is a sign of cloudy and rainy weather; after a long-lasting cloudy weather, fog appears. The appearance of fog indicates that the clouds in the sky have thinned, cracked and dissipated, and the ground temperature has dropped, causing water vapor to condense into radiation fog. The fog will disappear after sunrise and sunny days will appear.

In the morning of the warm season, if fortress-shaped clouds appear on the horizon, it means that the moist air layer at this height is already very unstable. By noon, once low-level convection develops, the unstable layers above and below combine, Strong convective motion will occur, forming cumulonimbus clouds and causing thunderstorms. Hence the proverb "The pagoda is clouded in the morning, and the rain pours in the afternoon."

In addition, clouds with weather signs often have a certain degree of continuity, seasonality and locality in their evolution. When the clouds in the sky move continuously from a distance in the order of cirrus, cirrostratus, altostratus, and nimbostratus, and gradually change from less to more, from high to low, and from thin to thick, it is a sign that something is coming soon. There will be rainy weather; on the contrary, if the clouds change from low to high, from thick to thin, and from layers to scattered clouds, there will be no rainy weather. In the warm season morning, if there are isolated clouds with a flat bottom and a convex top in the sky (pale cumulus clouds), or white broken clouds that move quickly (broken cumulus clouds), it indicates that the middle and low air layers are relatively stable and the weather is good.

In addition, the color of clouds can also predict certain weather conditions. For example, the color of hail clouds is first white on top and black on the bottom, and then red appears in the clouds, forming a mess of white, black, and red cloud filaments. It is earthy yellow in color. Black is caused by the inability of sunlight to penetrate the cloud; white is the result of clouds scattering or reflecting sunlight indiscriminately; red and yellow are caused by certain cloud droplets in the cloud (with a diameter between one thousandth and one hundredth of a millimeter). The phenomenon of selective scattering of sunlight. Sometimes the rain clouds also appear light yellow, but the clouds are even in color and not billowing randomly. There are also many proverbs that predict hail will fall based on the color and shape of clouds. For example, there are proverbs in Inner Mongolia such as "We are not afraid of darkness in the clouds, but we are afraid of black clouds mixed with red, and we are most afraid of white worms growing under yellow clouds." There are proverbs such as "Hail is going to fall", "Black clouds, yellow clouds, soil and red clouds, if the clouds come and go again and again, the hail will cause serious disasters". There are also sayings such as "black clouds roll into balls in the afternoon, wind, rain and hail come together", "the sky is yellow and sultry and dark clouds roll in, and the water in the Milky Way roars to prevent ice eggs". These all indicate that when air convection is strong, clouds develop rapidly, like thick smoke. When the ground rushes straight up and the clouds roll up and down and back and forth, hail is likely to fall.

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