[Article déjà publié le 27 juillet 2014]
If the atmosphere is wet and large temperature differences exist between soil and air, the many water molecules that make up this heavy cloud – they can weigh up to hundreds of thousands of tonnes! – are driven by ascending currents.
By separating, the water molecules generate an electric field in the sky
The finest arrives quickly at the top by loading positively, the heaviest stagnate at the base and are negatively loaded, giving the cloud its threatening gray appearance. It is by separating that the water molecules generate an electric field within the cumulonimbus, whose lightning is the consequence.
The flash discharges the accumulated electrical tension in a few milliseconds, and lightning blows fall on the earth which was positively loaded in response to intense activity above it.
For their part, the fine particles of water continued to rise in the atmosphere. Under the effect of cooling the temperatures at altitude, they condense in drops of rain, gries, even hail. Hence the rain and simultaneous lightning.
But all thunderstorms are not accompanied by rain …
The fact remains that, as Frédéric Nathan, forecaster in Météo France points out, “we can have lightning without having precipitation”. This is what happens in very dry weather, when the molecules accumulated at the top of the cloud are not numerous enough to condense each other, but that the friction resulting from their differentiation according to their mass cause de facto electrical activity.
We then speak of stormy clouds and not cumulonimbus, because the amount of water present in the atmosphere is not sufficient.
—M.Go.
According to S&V n ° 1154
With an unwavering passion for local news, Christopher leads our editorial team with integrity and dedication. With over 20 years’ experience, he is the backbone of Wouldsayso, ensuring that we stay true to our mission to inform.
