Changes in the weather

Weather refers to the changes of atmospheric sports boxes such as rain or shine, wind and rain, hot and cold in a short period of time. Weather can not only benefit human

Weather refers to the changes of atmospheric sports boxes such as rain or shine, wind and rain, hot and cold in a short period of time. Weather can not only benefit human beings, but also affect human activities and safety, bringing extreme heat, frost, drought and flood, heavy rain, hail and other disasters.

Moisture in the atmosphere

The lower atmosphere consists of dry and clean air, water vapor and impurities. The moisture in the atmosphere mainly comes from the ocean, as well as the evaporation of rivers, lakes and swamps, reservoirs, wet things and the transpiration of plants on the mainland. After water vapor enters the atmosphere, it is dispersed in the atmosphere due to its own molecular diffusion and airflow transmission. Clouds, fog, rain, snow, hail, frost and dew are the transformation forms of moisture in the atmosphere under certain conditions. For example, if the temperature is above 0℃, atmospheric precipitation is rain; The temperature below 0℃ is snow; When the air rises strongly, it may form hail; When the water vapor in the air is saturated, the excess water vapor will condense into fog or cloud. It can be seen that the moisture change in the atmosphere is the main aspect of weather change.

Common weather phenomena

Rain: Droplet-like liquid precipitation, mainly ice crystals or snow particles in the cloud, increases continuously due to the transfer, collision and merger of water vapor until the updraft can't support it, and then falls and melts. There are also liquid water droplets that increase or decrease directly. Raindrops are also heavy enough to be clearly visible when falling. When it rains, the clouds are mostly nimbostratus (or high-level clouds), which are evenly distributed throughout the day, sometimes cumulonimbus clouds.

Snow: Six-branched star, hexagonal or columnar solid precipitation composed of ice crystals. Because of the low temperature, water vapor condenses directly in the air. Sometimes there are needle-like crystals, and when it is not very cold, many snowflakes dissolve into clusters (like cotton wool). The snowfall in nimbostratus (even cirrostratus) is continuous, and the snowfall intensity has not changed much. When it snows, the sky is mostly covered with clouds evenly.

Frost: It is a kind of white brittle ice crystal in which water vapor in the air near the ground directly condenses on the ground or near-earth objects below 0℃. Sometimes when the temperature drops below 0℃, dew freezes into ice beads, also called frozen dew, which is also a kind of frost. Frost usually occurs at night or early morning, when there are clear clouds, still winds or breezes, sometimes at night and during the day. Frost will cause freezing damage to crops, and it can be prevented by smoking, mulching, irrigation, water spraying and burning heavy oil.

Fog: Fog is formed by condensation or sublimation of water vapor in the near-surface atmosphere after saturation. Generally speaking, the weather phenomenon that the horizontal visibility is less than 1 km caused by countless small water droplets or small ice crystals suspended in the air near the ground is called fog. The decrease of ground temperature and the increase of water vapor are the basic conditions for fog formation. According to its intensity, it can be divided into fog with visibility less than 50m, fog with visibility less than 50-200m, medium fog with visibility less than 200m and light fog with visibility less than 500- 1000m. The temperature below 0℃ in fog is called cold fog, and the temperature above 0℃ in fog is called warm fog. Heavy fog has a great influence on transportation and people's lives.

Hail: It is a kind of solid precipitation falling from cumulonimbus clouds. It mainly occurs when convection develops vigorously in the transitional season at the turn of spring and summer. Hail has many shapes, such as sphere, cone, ellipsoid or other irregular shapes. Hailstones vary in size, the most common diameter is between 0.5 and 3 cm, and the largest hail can weigh several kilograms. There have been 4.5 kilograms of hail in China, but the probability of big hail in the world is relatively small.

Typhoon: Typhoons cover a wide range, ranging in diameter from several hundred kilometers to Qian Qian meters, and some are as small as one or two hundred kilometers or even smaller. According to its structure and weather conditions, it can be divided into three parts: edge (peripheral gale area), main body (vortex storm area) and center (typhoon eye, diameter 10-60 km). There are many strong winds and showers on the edge. The territory is densely covered with clouds, the wind is often above 12, and the daily precipitation can exceed 100 mm, which is the strongest part of the typhoon. The typhoon center is also called typhoon eye, with an average diameter of 25 kilometers. The air pressure here is very low, which produces upward suction and causes rough waves at sea. Due to the prevailing downdraft, the wind is weak, but there is no rain for a short time, sometimes even sunny.

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Typhoon brings strong winds, heavy rains, huge waves and high tides, which are quite destructive and have a great direct impact on agriculture, fisheries and navigation, so it is a large-scale disastrous weather.

Typhoons sometimes bring people some benefits. The precipitation caused by it can alleviate or alleviate the summer drought in the southeast coastal areas. Typhoon in autumn can increase the storage capacity of reservoirs in South China for irrigation in winter and spring.

Weather change and human life

Weather change and human health

Traditional Chinese medicine believes that people and the environment are a whole, and changes in the environment often have a great impact on people's health. According to the research results of medical meteorology at home and abroad, about 40% deaths occur under abnormal meteorological conditions. This phenomenon is attracting more and more attention. The most obvious change in weather is the change in temperature. Statistics show that when the minimum temperature drops from 0℃ to 0℃ to _F, or the temperature drops by more than 8℃, the number of cold patients will increase obviously after one or two days. Cold is an important cause of many diseases. Cold stimulation can significantly increase the blood pressure of patients, and the higher the original blood pressure, the greater the increase, which will significantly increase the incidence of cardiovascular diseases such as stroke, angina pectoris, myocardial infarction and myocarditis. In addition, due to the rapid change of weather and the sudden drop of temperature, the gastric acid secretion and mucosal resistance of human body have changed, which often leads to the attack of gastric ulcer. China has a vast territory and changeable climate. When the weather changes, we should pay attention to our own health care and strengthen preventive measures.

Mood is related to the weather.

Meteorological conditions and their changes not only affect people's physical health, but also have a very obvious impact on people's psychological mood. Research shows that high temperature, high humidity, rainy weather and some abnormal weather are not conducive to people's mental health. Generally speaking, the low temperature environment is conducive to the formation of a good mental state, while when the temperature is high or rising, people's mental state is prone to fluctuations and abnormalities. Because high temperature is not conducive to people's mental health, the crime rate in high temperature environment is relatively high. 1996, on the eve of the Olympic Games, the American police appointed experts to conduct a detailed study, and found that the total number of crimes in Atlanta increased with the increase of temperature every day, with the highest crime rate in the hottest June and July.

There is an old saying that "the sky is dark", which means that in the rainy season, people's spirit is lazy and their mood is not carefree. Through in-depth research, Chinese medical meteorologists found that rainy weather affects people's mental health mainly because the light in rainy weather is weak and the human body secretes more pineal hormones, so the secretion concentration of thyroxine and adrenaline is relatively reduced, and people's nerve cells are therefore "lazy" and become less "active", and people will become listless.

The influence of meteorological conditions on mental health has attracted great attention from psychologists, behaviorists and management scientists. Some countries publish weather forecasts, as well as physical and psychological diseases that may be caused by future weather, as well as suggestions on disease prevention measures that "adapt to the weather".

D, disastrous weather

It refers to cold wave, frost, typhoon, strong wind, dry hot wind, hail, rainstorm, long drought and long rain, which cause serious harm to industry, agriculture, transportation and people's lives and property.

bitter cold

It refers to the phenomenon that the temperature of soil and plant surface and the air layer near the ground drops rapidly to 0℃ or below (sometimes slightly higher than 0℃) during the crop growing season, so that crops are frozen. Also known as "black frost", it is because the stems and leaves of crops are soaked in water after being frozen, and then the branches and leaves wither and die, turning gray-black. Frost is often accompanied by frost (hoarfrost), but if the water vapor in the air is not saturated at that time, frost may not appear at the same time.

The worst frost occurs on a clear night or early morning after a cold front.

Frost is most likely to occur in early autumn and late spring. Frost may occur all over China, especially in North China and Northwest China. There is less frost in southwest and south China, but severe frost may occur in some years. The severity of frost in different places is affected by topography and surface properties, such as depressions, valleys and slopes. Cold air is easy to sink and accumulate, and frost is the most serious.

Different crops have different resistance to low temperature, and the same crop has different cold resistance at different development stages.

First frost can be prevented, and our working people have accumulated rich experience. If the temperature of farmland or soil is raised to not lower than or close to the frost temperature by means of fumigation, irrigation and mulching before the frost occurs, the harm of frost to crops can be avoided or greatly reduced.

cold wave

Cold wave is a large-scale strong cold air activity, which generally appears in autumn, winter and early spring. When hit by a cold wave, it often causes severe cooling, strong winds and precipitation in the mobile areas. On average, there are about 3 to 4 national cold waves in winter half a year in China, which generally starts in late September and ends in May of the following year. It takes about 3 to 4 days for each cold wave to break out and end (move out of China). The outstanding performance of cold wave weather is strong wind cooling. Generally, the wind speed can reach 5-7, and it can reach 6-8 at sea. Sometimes strong winds of 12 can occur in a short time, and the duration of strong winds is mostly 1-2 days. Northwest China and Inner Mongolia have the strongest gale intensity. After the cold wave transits, the temperature drops suddenly, and the cooling can be sustained 1 less than a few days. There is more cooling in northwest and north China, and the cooling in central and southern China is reduced due to the southward movement of cold air. Cooling can also lead to frost and freezing. In spring and autumn, in addition to strong winds and cooling, there are often sand blowing and sandstorms in the north in cold wave weather, and there are more opportunities for precipitation than in winter.

typhoon

Typhoon is a super-strong low-pressure air vortex formed in tropical ocean. Typhoon affecting China is a tropical air vortex from the northwest Pacific and South China Sea. The regulations of the meteorological department are: the maximum wind force near the center 12 or above is called typhoon; 10 ~ 1 1 is called a severe tropical storm; 8 ~ 9 grades are called tropical storms; 8 hereinafter referred to as tropical depression. The center of the typhoon is calm, called "eye of typhoon", and the outside of the eye of typhoon is the storm area. Typhoon has a great impact on the southeast coastal areas of China (such as the coastal areas of Guangdong, Fujian, Zhejiang, Taiwan Province and other provinces), causing great losses to the lives and property of local people. Typhoons occur in summer and autumn, and the rainfall brought by nitrogen typhoons can appropriately alleviate the drought caused by the "summer drought" weather in East China and South China.