Why does the cold front rain after the front, and is the cold front raining before the front or afte

First, the strength of the cold and warm air masses in the cold front and warm front is different, which determines the type of front and the direction of forward advance. If the cold air mass is strong, it will actively move (see the direction of the arrow of the cold air mass in the cold front and weather map), which is a cold front, and the cold front moves in the same direction as the cold air mass. If the warm air mass is strong, the warm air will actively move, and the cold air mass will be forced to retreat, which is a warm front, and the warm front will move in the same direction as the warm air mass.

The key here is that the cold air mass actively moves as a cold front, and the cold air mass is forced to retreat (see the direction of the arrow in the figure) as a warm front.

Second, the front symbols are different. is a cold front symbol, where the opposite direction of the triangle is the direction of the cold front movement. It is the symbol of the warm front, in which the direction of the semicircular arc is the direction of the warm front.

Third, the slope of the front is different. The slope of the front is the angle between the front and the ground. The large angle between the front and the ground indicates that the front slope is large, and it is generally a cold front.

The angle between the front and the ground is small, indicating that the front slope is small and is a warm front. The slope of the front is related to the speed of the front. The cold air mass in the cold front pushes the front to move rapidly, and the warm air mass on it is strongly lifted, and the front slope of the cold front is large.

In the warm front, the warm air mass slowly climbs above the cold air mass, which pushes the front to move slowly, so the slope of the front is small.

Fourth, the weather changes during and after the transit of the cold and warm fronts are different. When a cold front crosses, weather phenomena such as wind, cloudiness, precipitation, and cooling often occur. After the cold front passes, the cold air mass replaces the original warm air mass, so the air pressure rises, the temperature and humidity decrease, and the weather becomes clearer.

When a warm front is crossing, weather phenomena such as cloudy skies and rain often occur. After the warm front passes, the warm air mass replaces the original cold air mass, so the air pressure drops, the temperature rises, and the weather clears.

Fifth, the range of rain areas of cold and warm fronts is different. The precipitation of the cold front is concentrated behind or near the front, and the rain area is narrow. The precipitation of the warm front is all in front of the front, and the rain area is wide.

Sixth, the passage of cold and warm fronts has produced different precipitation characteristics. The cold front lasts for a short period of time due to its fast movement speed and high precipitation intensity. Due to the slow movement of the warm front, the precipitation intensity is small and lasts for a long time, and the precipitation is mostly continuous.

Seventh, the impact of cold and warm fronts on China's weather is different. The heavy rain in the summer in northern China and the cold wave that broke out in winter in China are mainly caused by the passage of cold fronts. Therefore, the cold front has a great impact on the weather in China, while the warm front has a small impact and does not occupy an important position.

It is not difficult to conclude that the distribution of hot and cold air masses in warm and cold fronts is not difficult to draw from this:

It's an old saying that when it's cold, it rains?

The cold front rains after the front, and the warm front rains in front of the front. The cold front is often referred to as the cold air front, which is the vanguard of the cold air from the south, and is the most common weather system affecting China, especially in the winter half of the year.

Every few days in winter, a stream of cold air invades the interior from northwest and north China. When the cold front transits, it will be accompanied by the northerly wind increases, the air pressure rises and the temperature decreases, sometimes causing rain and snow, and even heavy rain in summer.

The weather conditions of a cold front can be broadly divided into two types:

Type 1: Cold fronts move slowly, have a small slope, and are in front of the 700hpa trough in the air, often referred to as Type 1 cold fronts. This type of cold front, because the cold air mass moves forward on the one hand, the warm air mass in front of the front moves forward on the one hand, and on the other hand, it is forced to slide upwards along the frontal surface, and when the water vapor conditions are sufficient, clouds and precipitation are generated on the front.

Type 2: The cold front moves quickly, has a large slope, and is located behind or near the 700hpa trough in the air, which is often called the second type of cold front. The cold advection above this type of cold front is stronger, the air flow is sinking, and only the warm air near the ground front is lifted, but the front slope is large, and there is a strong upward movement.

Why: Precipitation requires air to rise and cool, and then precipitation is formed. When a warm front encounters colder air during movement, it will actively rise, forming the conditions for precipitation, so there will be precipitation at the moving front.

On the contrary, a cold front tends to move downward when it encounters relatively hot air, and the air behind the front is forced to lift and form precipitation.

The strength of the cold and warm air masses in the cold front and warm front is different, so the type of front and the direction of the forward forward are also different. A cold front is a front in which a cold air mass actively moves towards a warm air mass (Figure a). In the diagram, the cold air mass part is generally drawn with an arrow in the direction of the forward propulsion of the cold air mass, which is in the opposite direction to the arrow of the air flow movement of the warm air mass that is forced to lift on the front.

A warm front is a front in which a warm air mass actively moves towards a cold air mass (Figure B). In the diagram, the direction of the air flow of the warm air mass climbing along the front is the same as the direction of the cold air mass on the other side of the front.

Rain after front. A cold front is a rain after a front, and when cold and warm air meet, the junction area formed becomes a front area or front, or a front, or a front. Due to the configuration of the cold front and the upper-air trough, the speed of movement and so on, the distribution of clouds and precipitation near the cold front is also significantly different.

Because the cold air is heavy and the warm air is light, when the cold air mass moves, the cold air mass will be actively wedged under the warm air mass and form a front at the junction of cold and warm air. When a cold front is transiting, cumulonimbus clouds, thunderstorms and heavy precipitation are common. If the cold front moves quickly, the cumulonimbus clouds will be distributed in a narrow area before the front, and the cloud will quickly turn to clear after the front. If the cold front moves slowly, it will form a wide range of Altostratus and Nimbostratus.

The location of the cold front

The intensity of the cold front, which is strongest in winter, can often drive directly over South China and the South China Sea, resulting in cold waves. In summer, the cold front is weaker and mainly moves in the north, and the cold front in summer often brings thundershowers.

North China is a necessary place for cold front activity in China. In the Northeast, there are cold fronts throughout the year, especially in spring and autumn. There are three types of cold fronts in these two areas: West Road, Northwest Road, and North and Northeast Road.

In winter, cold fronts mainly cause cooling and high winds, and in summer, thunderstorms can occur. In spring, cold fronts tend to cause strong winds and precipitation in Northeast China, while in North China, they tend to cause only windy and sandy weather.

The above content reference: Encyclopedia - Cold Front.

After judging the cold and warm fronts and their fronts, you can look at the symbols on the weather map and the direction of the movement of the air mass

1) On the weather map, the cold front is represented by a triangle, and the direction of the triangle arrow is the front; The warm front is represented by a semi-circular shape, and the direction of the semicircle is the front of the warm front

2) The cold front is moving to the side of the warm air mass, and the front is moving to the side of the warm air mass; Moving towards the side of the cold air mass is a warm front, and on the side of the cold air mass is a front

Therefore, the answer is: (1) Judging from the legend.

On the weather map, the cold front is represented by the shape of a triangle, and the direction of the triangle arrow is the front; The warm front is represented by a semi-circular shape, and the direction of the semicircle is the front of the warm front

2) Judging by the direction of movement.

Moving to the side of the warm air mass is a cold front, and on the side of the warm air mass is a front; Moving towards the side of the cold air mass is a warm front, and on the side of the cold air mass is a front