In Meteorology, What Is an Air Mass?
An air mass is a large air mass with relatively uniform horizontal distribution of meteorological elements (mainly temperature and humidity) and a certain vertical stability. In the same air mass, the focus distribution of meteorological elements is almost the same, and the weather phenomenon is also roughly the same. The horizontal range of air mass can reach several thousand kilometers, and the vertical height can reach several kilometers to more than ten kilometers, often extending from the ground to the top of the troposphere. There are three main methods for classifying air masses. One is to divide them into cold air masses and heating masses according to the thermal properties of the air masses; the second is to divide them into dry air masses and wet air masses according to the differences in the humidity characteristics of the air masses. The origin of air masses is often divided into arctic ocean air masses, polar air masses, tropical air masses, and equatorial air masses.
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- Air mass concept
- An air mass is a huge air mass with a wide range (usually thousands of kilometers) in the horizontal direction with uniform temperature and humidity properties.
- The temperature, humidity and other properties of the air mass reflect the properties of the source where it is generated.
- The physical properties of air masses in the horizontal direction mainly refer to
- In order to analyze the characteristics and movement laws of air masses, air masses on the earth are often classified, and the classification methods
- In winter, meteorological forecasters often say, "Because the continental air mass travels south .........", what is a continental air mass? it is
- Disc vortex air mass
Air mass cold current
- Wow! so cold! Pedestrians on the road looked like mules, waiting for the quilt to go out. It turned out to be a "cold current". When the continental cold air mass moves south, the cold air current will cause the temperature to drop rapidly. But how many degrees does the temperature have to drop to count as a cold current? Usually in meteorological forecast, when the daily minimum temperature in Taipei is predicted to drop to 10 ° C or below, it is called cold current.
Three sentences of air mass
- Strong continental cold air mass; continental cold air mass; northeast monsoon strengthening;
- Have you noticed that the timings of the above three nouns are different? In meteorological forecast, if it is predicted that the cold air mass will reduce the daily minimum temperature of Taipei to between 12 ° C and 14 ° C, it is said to be affected by the "continental cold air mass"; if it is predicted to drop to 12 ° C or below, it is said to be affected by " Strong continental cold air mass "; if the minimum temperature does not drop to 14 ° C, it will only be said to be affected by the" intensification of the northeast monsoon ". You can tell the difference in the seriousness of these three phrases.
Air mass degeneration
- The cold current is coming, freezing people like popsicles. When can the weather get warmer? At this time, I had to look forward to the "denaturation" of the continental air mass. Because when the continental cold air mass moves out of the source area, it will change its nature under the influence of the passing environment and its internal movement, and become a "denatured continental air mass." With it, the weather will not be so cold and the temperature will not drop anymore. .
- The continental cold air mass is a high-pressure center, which is represented by "H" on the weather map. It gradually degenerated on the way to the south. By the time of East China, it had formed a "denatured continental air mass". After its degeneration, the high-pressure center shifted eastward, moving from East China to the East China Sea and continuing eastward. At this time, the cold front at the front of the air mass has passed through Taiwan. The hazy weather has improved, the cloudiness has decreased, the temperature has risen, and even fine weather will appear. This situation is called "mobile high pressure".
- If the mobile high-pressure center continues to move from the East China Sea to the east, it will bring warm and humid air currents to Taiwan. The temperature will rise significantly everywhere, and even sunny and comfortable weather will occur. The air flow that causes this weather phenomenon is called "high pressure return ".
Air mass front
- Think about it: what happens when the air-conditioning mass meets the heating mass? In meteorology, when they meet, they will produce a band-shaped interface called the front. The frontal belt is hundreds of kilometers short and thousands of kilometers long. It gradually widens with height from bottom to top and appears inclined. The cold air is below and the warm air is above. The structure is as shown in the figure. .
- The front will advance with the movement of cold and warm air, and it is divided into four types: cold front, warm front, detained front, and imprisoned front, and it causes four different types of weather patterns. The most common type in Taiwan is Cold front and stranded front.
- When the cold air front moves in the direction of warm air, it is called a "cold front". When this front passes, the ground temperature will decrease and become cold. There is a difference between the cold front movement and the slow running cold front. The warm air rises slowly and steadily, while stratified clouds appear, and the rainfall eases. The fast running cold front, the warm air rises rapidly due to the violent impact of cold air, causing thick rain. Clouds, at this time there will be heavy storms on the ground.
- If the force of warm air is stronger than that of cold air, and the front moves in the direction of cold air, a "warm front" will be formed, which will increase the temperature of the passing area. The front of the warm front is a large area of cloud and rain, covering hundreds of kilometers, causing continuous rainfall. The rainfall pattern is different from the cold front.
- A cold or warm front is a front that occurs when one side of the cold or warm air is strong. However, if both sides of the cold and warm air are close to each other, the front cannot move quickly, but hovering and staying in place, causing the cloud and rain weather to occur simultaneously with the cold and warm fronts.
- Finally, we have to explain "Prisoner Feng". When the front is moving, if the cold front catches up with the warm front or the two cold fronts overlap and meet each other, the front and the front pull together without concession, and the last two fronts will merge into a prisoner front. The resulting cloud system and rainfall have both frontal characteristics and become more complicated.
- "Tropical ocean air mass" is the high pressure located in the Pacific Ocean, also known as "subtropical high pressure". It settles in the Pacific all year round, so it is also called "Pacific High Pressure" or "Pacific Air Mass."
- The intensity and range of tropical ocean air masses change due to the cold and warm seasons. When the seasons warm, it will also become active as the intensity and range greatly increase, causing Taiwan and China to blow warm and humid southwest and southeast winds. Is the main cause of seasonal rainstorms. Due to the different locations and extents of tropical ocean air masses, the weather patterns are different. Its edge belongs to the cloud and rain zone, which makes the ground easy to rain and the rain is heavy. In weather forecast, it is called: affected by "Southwest air current" or "Southerly air current"; if it causes the weather pattern of afternoon thunderstorms, then It is affected by the "tropical ocean air mass"; if the center of the air mass moves over Taiwan, the weather is sunny and hot, it is called "high air pressure envelope".
- Air mass and front
- Air masses are a wide range of temperature and humidity distributions in the horizontal direction, and a large range of air masses with similar temperature and humidity changes in the vertical direction. Their horizontal area ranges from millions to tens of millions of square kilometers, thickness and kilometers. To ten kilometers. When an air mass is close to another air mass, there is a transition zone (interface) between the two because of their inconsistent physical properties. This transition zone is called the front, and the intersection of the front on the ground is called the front. This is the usual weather. The so-called "front".
- Under the influence of atmospheric circulation, meteorology moves from one area to another, such as from land to the ocean. During the movement of the air mass, the front of the two air masses will also be caused to move accordingly. This will cause a series of weather changes in the area where the air mass and the front pass, which is the aperiodic change of the weather.
- According to the origin of the air mass, it can be divided into four categories: ice ocean air mass, polar air mass, tropical air mass, and equatorial air mass. However, it is customary to classify the thermal mass of the air mass. Any temperature at which the humidity of the air mass is higher than the underlying surface (ground) is called temperature. Air mass, the opposite side is called cold air mass. That is, the air mass moving to the cold area is a heating mass, and its front is a warm front; the air mass moving to the warm area is a cold mass, and its front is a cold front. When the cooling and heating groups have the same power, the front moves slowly or is at rest. When the cold front moves much faster than the warm front, the cold and warm fronts merge to form a front, which is the cold front.
- The activity of cyclones and anticyclone clusters and fronts is not an isolated phenomenon, it is related to a certain distribution of large airflow fields. Cyclones and anti-cyclones are important components of large airflow fields. A cyclone is a horizontal vortex whose central pressure is lower than its surroundings. The air flows counterclockwise in the cyclone region in the northern hemisphere, and the opposite in the southern hemisphere. Anticyclone is high pressure. It is a horizontal vortex whose center pressure is higher than the surrounding pressure at the same height. In the northern hemisphere, the air in the anticyclonic region flows clockwise; the southern hemisphere is the opposite.