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The Effects of Cold Air and Countermeasures
2017-10-19 16:31:00 gdemo.gov.cn

The Definition and Intensity of Cold Air

 

Cold and warm air are distinguished by the temperature variations in horizontal orientation.  The air in low temperature zones is called “cold air” in Chinese. The remote Arctic Ocean and bitterly cold Siberia are cradles for cold air.

 

The northern cold air mass is mostly formed on the polar and Siberian continent, with a breadth of thousands of kilometers and a depth ranging from several to dozens of kilometers.  The passage of cold air brings rain or snow, etc. and sudden drops in temperature. The intensity of cold air and the cooling range are varied each time. Cold air flows like waves, and its coverage is wide, extending over 2 kilometers in length. Due to variations in path of movement, the areas affected vary.

 

According to the intensity of cold air, China divided it into 5 levels, according the designations in Chinese language: weak cold air, moderate cold air, strong cold air, severe cold air and cold wave.

 

Weak Cold Air

 

Cold air that causes a fall in the minimum temperature by less than 6 degrees Celsius within a 48-hour period.

 

Moderate Cold Air

 

Cold air that causes a fall in the minimum temperature by more than or equal to 6 degrees to lower than 8 degrees Celsius within a 48-hour period

  

Strong Cold Air

 

Cold air that causes a fall in the minimum temperature by more than or equal to 8 degrees Celsius within a 48-hour period, with the minimum temperature still higher than 8 degrees Celsius

 

Severe Cold Air

 

Cold air that causes a fall in the minimum temperature by more than or equal to 8 degrees Celsius within a 48-hour period, with the minimum temperature still lower than or equal to 8 degrees Celsius

 

Cold Wave

 

Cold air that causes a fall in the minimum temperature by more than or equal to 8 degrees Celsius within a 24-hour period or by more than or equal to 10 degrees Celsius in a 48-hour period, with the minimum temperature still lower than or equal to 4 degrees Celsius

  

The Effects of Cold Air and Countermeasures

 

The invasion of cold air brings a fall in temperatures and strong winds and sometimes large-scale rain or snow showers, which is caused by the intersection of cold and warm air.  The invasion of cold air will not necessarily bring precipitation when the conditions of the warm wet air and circulating current are unfavorable.  Therefore, it is not true that the stronger the cold air, the heavier the rain and snow.

 

The Effects of Cold Air on Human Bodies

 

First, severe cold air will cause an obvious drop in air humidity. Mucous membranes of nasopharynx will become dry and result in small cracks, from which a flu virus may enter.  Meanwhile, the fall in temperature will lead to a drop in nasopharynx local temperature to around 32 degrees Celsius, a temperature suitable for virus to grow in mucosa cracks. Meanwhile, the upper respiratory tract, irritated by the severe cold air will cause local vasoconstriction, and a corresponding drop in immunoglobulin secreted by the mucous membrane follows. All of above would create favorable conditions for a flu virus to invade and reproduce.

 

Second, in 2-3 days after the invasion of severe cold air, a sharp fall will follow in average temperature and minimum temperature. The thermoregulation of human bodies can hardly adapt to the sudden cold. People are prone to colds and the flu if they don’t wear additional layers of clothing to keep warm. Furthermore, the body’s resistance will decline, thus creating opportunities for all kinds of flu viruses.

 

In addition, due to the drop in temperature, the cilia activity of bronchial epithelium will become less active, and exertion ability of the trachea will decline. As a result, the bacteria in the respiratory tract can easily spread downward which will render people more chronic bronchitis-prone and can aggravate chronic bronchitis. Although pneumonia is an infectious disease caused by viruses or bacteria, its initial infection and aggravation are related to the activity of cold air.

 

During the passage of severe cold air, the incidence and mortality of pneumonia cases will rise. Due to weak or deficient pulmonary function, infants are vulnerable to pneumonia. Particular care should be taken for infants during sudden changes in weather. TB patients’ conditions are prone to get worse during a period from 15-20 hours before the passage of cold air to 7 hours after.

 

During cold-air periods, people ought to get more exercise, keep warm and arrange daily life so as to prevent their bodies from getting cold.

 

The Effect of Cold Air on Agriculture

 

When cold air invades, farming operation management should be reinforced to mitigate the impact of colder temperature and strong winds. Greenhouses should be reinforced against the wind. In North China, in the Huang-huai and Jiang-huai Region, measures against low temperature and frost should be taken. In Xinjiang, cotton should be harvested immediately. In Inner Mongolia, measures should be taken to protect livestock against wind and cold.

 

Measures should be taken wind and rain or snow in order to protect greenhouses, preserve pasture grazing and ensure transfer and transportation of produce. Ripened corps and fruits should be harvested when the weather is fine or before the frost in order to prevent greenhouses and produce from being destroyed by low temperatures and frost.  In Northeast China, the soil should be loosed before the freeze-up to prepare for the next year. In the winter wheat area, field management should be conducted according to rainfall and soil moisture content and to ensure the winter wheat sown or sprouting can thrive in the spring. Prevention of diseases, pests and weeds should be strengthened to develop robust seedlings.  In some areas in the south-east of Northwest China, middle-south of North China and the Huang-huai Region, where winter wheat is not planted, stubble should be removed, soil preparation should be made, and rush-plant should be seeded while the soil is damp, or the soil should be dampened for timely sowing to ensure the growth of seedlings before winter.

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