The sowing of the clouds consists in introducing particles into a cloud in order to start precipitation.

The condensation of the steam in liquid water for the formation of the Cloud S and precipitations requires the presence in the Air of cores of solid condensation. Direct condensation without cores is not strictly speaking strictly impossible but it is thermodynamically very unfavourable. The quantity of cores of condensation in the air can thus be a factor limiting to the passage of the atmospheric steam out of liquid water (Nuage, Précipitation).

To start precipitations

The sowing of the clouds by cores of Iodide of money, for example, can thus support the formation of the clouds and Précipitation S. Nevertheless, if the presence of cores of condensation proves to be quasi-necessary, it is not sufficient: the thermodynamic state of the atmosphere must absolutely allow condensation (role of the quantity of steam, temperature, pressure etc). The sowing of the clouds is not thus to in no case a miracle solution with the problem of Sécheresse.

The products most frequently used for the sowing of the clouds are:

• Iodide of money
• Sodium chloride
• Alginates
• Dry ice.

To fight against hail

Sowing can also be used when a Orage threat, to fight against the Grêle. The enrichment of the air in cores of condensation supports also the passage of the gas phase in solid phase, and thus the formation of hail. That appears contradictory, but there makes some is no paradox: the sowing of the clouds is supposed to support the formation of many hail of small size and thus to fight against the growth of a more restricted number of let us hail on the humidity of the atmosphere available.

Not very effective

Alas, the experimentation showed that if the limitation of the growth of hail thanks to sowing went in certain cases, it can just as easily prove without utility or worse, harmful even dangerous, by not preventing the growth of let us hail while increasing their number. The meteorologists are thus in their large majority unfavourable with this type of action.

See too

Related articles

• Hail
• Modification of time
• Anti-hail gun

External bonds

• North American Interstate Weather Modification Council
• Weather Modification Association
• American Meteorological Society Policy Statement

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