Extraordinary Mountain Clouds Part 2: Mont Blanc’s Hat

The Mont Blanc will be the center piece of your Tour du Mont Blanc, or your starting point if you hike the Chamonix to Zermatt Haute Route. It reaches as high as 4810 meters up into the sky, making it the highest mountain of the Alps, and even of Europe. And like all high mountains, Mont Blanc creates its own clouds (see previous blog: Extraordinary Mountain Clouds). Its most striking cloud has a very characteristic shape: it harmoniously mimics the shape of the mountaintop, covering the summit as if Mont Blanc is wearing a hat.

How the cloud is formed

In technical terms, this lens shaped appearance is called altocumulus lenticularis and its formed by a strong wind that blows over the Alpine giant and descends at the back of the mountain. The cloud becomes visible as soon as the air cools down near the summit and becomes saturated with water vapor. The cloud dissolves again when, at the back of the mountain, the air drops again causing the air to warm up.

For hours

Sometimes Mont Blanc will wear its hat for hours in a row. Although the lens cloud seems to be stationary in the same place, the air creating the cloud continues to flow; as long as the wind continuously blows from the same direction at the same speed and with the same amount of moisture, the cloud will stay visible in exactly the same spot.

Bad weather is coming!

The characteristic lens cloud is not only well known because of its beauty, but also because it’s letting you know a disturbance is on its way. When Mont Blanc is wearing its hat, the weather will most likely change. This is especially the case when the base of the “hat” is very low, keeping the summit completely out of sight. So, if you see this beautiful cloud above Mont Blanc, you better get your rain gear ready!

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Simone van Velzen

In her work as an alpine naturalist Simone adds an exciting new dimension to your Tour du Mont Blanc trek with insights into the incredibly rich flora and fauna of the Alps. Simone studied Wildlife Management at the Van Hall Institute in the Netherlands. After her studies she left her home country (which is flatter than a pancake) and moved to British Columbia. In the Canadian Rockies, she discovered the astonishing richness of mountain environments. Her passion for mountain nature was born. And when she returned to Europe, she based herself in Chamonix-Mont-Blanc, the perfect setting for exploring and studying the natural history of mountain environments. As an alpine naturalist she writes for outdoor magazines and leads excursions in the natural world.

If you step into the natural world with Simone, her passion for all living things—wild flowers to lichen, birds to mammals—can’t help but rub off on you. She’s excited to meet you on your Tour du Mont Blanc and share the amazing natural wonders in the Alps.

Latest posts by Simone van Velzen (see all)

• The Alps: A Biodiversity Treasure Trove - December 10, 2020
• Flora in the Alps – Spotlight on the Alpenrose - June 25, 2020
• Tour du Mont Blanc Hightlight: The Contamines-Montjoie Nature Reserve - May 21, 2020