Most of the glaze occurs in one month from early January
to early February or the middle ten days of February, it
starts early in north, late in south, early in mountainous
areas and late on plains, while it ends in an opposite way.
The glazed frost comes earlier in higher mountainous areas
and ends later. Take the Bright Summit of the Mount Huang
in southern Anhui province, the glazed frost generally
begins in early November and ended in April of the following
year for 5 months.
According to statistics, the frequency of glazed frost in
Yangtze-Huaihe river basin is once every 2 or 3 years in
the Huaibei region along the Huaihe river and once every 7
or 8 years in the south of Huaihe river. In mountainous
areas, however, there is a great difference between the
valley and the mountain top. There is almost no glazed
frost in some valleys in mountainous areas, while it occurs
almost every year in high areas.
The glazed frost is common in mountain and lake areas.
It appeared during the time from December to March in most
areas of China. The average features of glazed frost a year
in China are that there is more in the south and less in
the north. But there is no hail or glazed frost in southern
China because it is hardly close to 0℃ out of warmth in
winter. There are more glazed frost in wet areas and few
in dry areas (especially in high mountain areas where the
glazed frost is the most).
The stations, where the average number of days of glazed
frost is more than 20 to 30, are almost all in high mountainous
areas. Whereas the average number of days of glazed frost
of most stations in the plain area is below 5 days.
Most glazed frost commonly occurs during the warmer spring
and autumn in the north where winter is very cold, such as
the Tianchi meteorological station on Mount Changbai where
glazed frost mostly happens in May with an average of 5.7 days.
In September, glazed frost lasts 3.5 days on average there.
During the winter, from December to March due to the low
temperature glazed frost has never been seen.
While during winter in the south when it is colder, there is
more glaze, such as the meteorological station on Mount Emei
where there are up to 26.4 days with glaze on average in
December, and as many as 24.6 days in January. In some years,
glaze once occurred everyday in December, January and March.