Rare phenomenon –
An intriguing cloud cascade on the teeth-du-noise
A cloudy veil hit the northern slopes of the Valais massif on July 1ᵉʳ. This exceptional event was due to the thunderstorms of the day.
The cloud cascade of July 1 on the teeth-du-Midi sublimated by the setting sun.
Weather
- A rare cloud cascade illuminated the teeth-du-noon for twenty-five minutes.
- The thunderstorms of the day have created exceptional atmospheric conditions.
- The cold air was trapped in the Salanfe basin.
- West winds have caused a local Foehn effect.
A spectacular cloud waterfall formed on the teeth-du-Midi on 1is July, creating a rare natural spectacle observed by many witnesses in Valais. According to information from Weatherthis exceptional atmospheric phenomenon appeared in the evening after a day marked by heat and thunderstorms in the region.
The wonder occurred between 9:20 p.m. and 9:45 p.m., as confirmed by the fourteen photographs transmitted via the meteorological application and the surrounding webcams archives. This singular cloud formation, resembling a cascade hitting the northern slopes of the mountain range, captivated the attention of observers throughout the Rhône valley.
An air flow
The meteorological analysis suggests that this cascade results from an air flow down along the northern faces of the Du-du-Midi. By flowing on the slopes, the air compresses, warms up and dries up, causing the dissipation of the cloud before it reaches the bottom of the valley. This characteristic mechanism most likely corresponds to a local Foehn effect.
The phenomenon observed from Veytals on July 1 at 9:37 p.m.
Weather
The scarcity of this phenomenon is explained by the very specific conditions necessary for its training. The air must be forced above the Massif des Dent-du-Midi, while normally it bypasses this high and isolated mountain barrier. In addition, atmospheric humidity at the altitude of the summit must be sufficient to allow condensation and visually reveal the flow of air.
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The meteorological archives of the 1is July show low western winds at altitude, an inadequate orientation to explain a flow on the northern faces of the massif. The radar surveys, however, reveal the presence of thunderstorms circulating south of the Dut-du-Midi from west to east at the time of the appearance of the cloud waterfall.
The privileged hypothesis suggests that the cold downstream air of stormy cells has spread north from their base. This cold and wet, denser air found itself trapped in the Salanfe lake basin. Unable to evacuate sufficiently by the Van valley, it was forced to overflow above the mountain range. The gradual distance from the storm to the east would then have stopped the cold air influx, explaining the brief duration of the phenomenon observed between 9:20 p.m. and 9:45 p.m.
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