As a natural phenomenon, dust-haze can be caused
by factors from three aspects.
Increase of horizontal calm wind. Recently,
the friction coefficient of the ground has
been increasing with higher and higher
buildings as the city construction developing
rapidly, leading to weakened wind when it
is passing urban areas. More calm winds
is to the disadvantage of the extension
and dilution of atmospheric pollutants to
the outer space of the city and make high
concentration of pollution easier inside the city.
Vertical temperature inversion. The temperature
inversion layer is like a pot cover above the
city and creates temperature inversion that the
temperature of upper air is higher than that of
lower part. On the condition that the climate is
normal when pollutants can move to upper colder
air and be released to the atmosphere in this loop.
However, when vertical temperature inversion happens,
pollutant stays in the lower air because it is colder.
Increase of floating particles. As the industrial
development went on and on these years, more and
more motor vehicles appear and there were a great
larger amount of released pollutants and floating
particles in city. This is directly responsible for
the low visibility, which put all the city under a