Air movement - quite similar to the movements
which we know from the weather around us - occur also in any closed space
which is not totally isolated from the outside - e.g. in a glasshouse, a
wintergarden, in a cold storage space, in a conference room, but also
inside the cabinet of an electronic device.
If the climatic conditions of the closed space is
changed with regards to the "outside" - e.g. by means of heating,
cooling, humidification or desiccation - a local "micro-climate"
will be created.
This micro-climate is not only influenced by the artificial processes which
are installed, but also by outside influences like sunlight, insulation or
intake of fresh air.
According to the intended use of the space the
responsible person will try to create an optimal micro-climate which is
beneficial for the "inhabitants" (plants, animals, mushrooms,
In case it is necessary to humidify the air - by means of a fogging system
- a natural air circulation will occur.
Everybody knows that hot air has a lower specific
weight than cold air.
Hot air will rise up (thermic lift), cold air will fall down.
Furthermore we know that hot air can take up more water vapour as well as
that hot, unsaturated air will cool down by evaporating fog droplets.
With most fogging systems the feeder-pipes
together with the fogging nozzles are mounted in the upper parts of the
Following the application of fog the temperature of the surrounding air
will cool down by adiabatic cooling and will sink downwards.
It will replace the warmer air layers which have been located so far near
the floor which will rise towards the ceiling. Usually a rotating air
current will be formed after a short while - parallel to the feeder pipes
carrying the nozzles.
The rotation will be faster, if the treated air layers are hot and dry and
slower if the air is already cool and humid (as e.g. in a cold storage).
Therefore the air movement is NOT induced by
larger or smaller water droplets entering the air, but alone by the cooled
air layers which will sink down !