Meteorological disasters represent the direct or indirect damagy
for life and property of the people, national economy and
development of society, as well as some national defense construction.
It comes as one of the primary disasters of natural ones,
including weather disaster, climate disaster and secondary
and derivative disasters of meteorological disasters.
China is one of the few countries that suffer a heavy loss
due to those meteorological disasters. Since April 1st, 2010,
the Regulations for the Defense of Meteorological Disasters
has been put into effect.
Generally, weather disaster, climate disaster, secondary and
derivative meteorological disasters are included in meteorological disasters.
During which, the weather and climate disasters, is direct
attributed to the typhoon (tropical storm, strong tropical storm),
heavy rain (or snow), thunderstorms, hail, wind, sand, tornado,
dense fog (or thick fog), high temperature, low temperature,
an unbroken spell of wet weather, sleet, frost, icing (or ice accreting),
cold-air, drought, dry hot wind, heatwaves, floods, waterlogging
and some other factors. The secondary and derivative refer to those disasters
that caused by the meteorological disasters, such as landslides,
debris flows, storm surges, forest fires, acid rain and air pollution.
Meteorological disasters are of many kinds, and they have some
other characteristics, such as having a wide spreading range,
a long duration, a high frequency, a significant chain reaction
often and not happening solely, as well as a serious damage.
The meteorological classification of catastrophic weather levels
is solely for the purpose of observation and forecasting, and these levels
are not related to the actual levels of meteorological disasters.
It has been pointed out that the magnitude of the storm has nothing
to do with the occurrence of disasters. The same problem is found
in the classification of fog. On the highway, when the visibility is
less than 200 m, the speed of cars must be limited, and when less than
or equal to 50 m, the highway will be closed. However, there is no visibility
of 50 m in the meteorological observations specification, which results
in the lack of historical data for the visibility level of 50 m, which is
an important source of information for the risk zone of the fog. Fortunately,
where the visibility automatic observer is installed can obtain the observation
data of all kinds of visibility observations, which lay the foundation
for the forecast and risk assessment of fog.
Therefore, it is unfavorable to classify the disastrous weather scale
as the classification standards of meteorological disasters.
In fact, there is only one principle for classifying meteorological
disasters: disaste ausing principle. The grade of meteorological
disasters should be the level at which disasters occur, that is,
the occurrence of a certain level of meteorological conditions
will result in this level of disaster.
For example, the classification of wind power should be determined
based on the wind force that the ship, vehicle and house can withstand;
the level of wave should be divided according to the windbreak prevention
capacity of the breakwater; The visibility level should be determined
according to the needs of highway management; and the level of agricultural
meteorological disasters should be determined based on the degree of
damage to the crop. Besides, about some meteorological disasters that
cause damage to artificial engineering, the critical meteorological conditions
for them should be studied according to engineering design standards and
should be used as criteria for meteorological disasters. For example,
the classification of wire ice coverings should be based on the design
standards of the electric power sector; snow pressure rating shall be
determined according to the design standard of agriculture facilities
and so on. The advantage of this classification is that the level of
meteorological disasters is closely linked with the grade and risk
assessment of meteorological disaster forecasts. When a certain level of
meteorological conditions is predicted, some kind of disaster may occur.
When the forecasted minimum temperature is below -7℃/-9℃/-11℃,
citrus may suffer from mild/medium/serious freezing injury.
This is the case that weather forecast is turned into disaster prediction.