What is cold wave?
Cold wave is a disastrous weather in winter. Cold air coming down from high latitudes strengthens quickly under special weather conditions when entering middle and low latitude areas, which will bring sharp temperature down, gale and snowfall & rainfall. When southward clod air reaches the standards, it will become cold wave. Cold wave is a large scale weather process that could happen in anywhere of China causing frost, icing damages and other hazards.

From high to low, Cold wave warnings are issued following these standards:
1. Red Warning. In 24 hours, minimum temperature will drop at least 16 degrees Celsius, with minimum temperature lower than or equal to 0 degrees, and average land wind up to scale 6; or the temperature has dropped at least 16 degrees with minimum temperature lower than or equal to 0 degrees and average land wind up to scale 6, and this is likely to continue.

2. Orange Warning. In 24 hours, minimum temperature will drop at least 12 degrees Celsius, with minimum temperature lower than or equal to 0 degrees, and average land wind up to scale 6; or the temperature has dropped at least 12 degrees with minimum temperature lower than or equal to 0 degrees and average land wind up to scale 6, and this is likely to continue. 

3. Yellow Warning. In 24 hours, minimum temperature will drop at least 10 degrees Celsius, with minimum temperature lower than or equal to 4 degrees, and average land wind up to scale 6; or the temperature has dropped at least 10 degrees with minimum temperature lower than or equal to 4 degrees and average land wind up to scale 6, and this is likely to continue.

4. Blue Warning. In 48 hours, minimum temperature will drop at least 8 degrees Celsius, with minimum temperature lower than or equal to 4 degrees, and average land wind up to scale 5; or the temperature has dropped at least 8 degrees with minimum temperature lower than or equal to 4 degrees and average land wind up to scale 5, and this is likely to continue.

The Effects of Cold Wave

Cold wave and severe cold air will bring gale, temperature drop weather which is major disastrous weather of China. from 21 to 25 April 1969, strong wind hit Bohai Sea, Yellow Sea, and Hebei, Shandong, and Henan province bringing wind of scale 7 and 8 and marine gale of scale 8 to 10. The cold wave stirred up rare storm surges in Baohai Bay and Laizhou Bay.

Rain & snow and icing weather that induced by cold wave could adversely affect transport.

Cold wave also could cause health problems such as fever, tracheitis, coronary heart disease, apoplexy, asthma, myocardial infarction, angina pectoris and others.

For benefits, the cold wave could improve heat exchange between high latitudes and middle-low latitudes which could promote the ecological balance of nature. And for the people, cold wave would bring precipitations which will benefit crops in farmland.

Characteristics

The characteristics of cold wave vary in different geographical environment. In deserts of Northwest China and Loess Plateau, it produces gale with less snowfall especially sandstorm. In the Inner Mongolia grassland, it brings gale, snow and low temperature. In North China, and Yellow-Huaihe River basin, cold wave always brings wind and snow. In Northeast China, it could bring strong wind and heavy snow. In southern China, cold wave comes with rainfall.

Preventive Measures
When temperature drops quickly, people should add clothes especially keeping hands and face warm.
Close doors and windows and reinforce outdoor structures.
Mind slippery road when going out.
Senior people, the weak and patients should stay indoors.
Have proper rest and do not over fatigued.
Households that use coal stove should pay attention to gas poisoning.
Strengthen weather forecast and timely issue warnings in advance.

Editor Zhang Yong