Extraordinary Mountain Clouds Part 4: A Sea of Clouds

A sea of clouds is perhaps the most stunning cloud formation you can find in the Alps. It’s a very characteristic phenomenon in mountainous areas and it creates a surreal panorama with the valley hiding underneath a thick blanket of clouds from which peaks arise like islands out of a sea. In this series “Extraordinary Clouds”, I’ve already explained why you often see incredible cloud formations in the mountains. We also looked closely at the breathtaking lenticular cloud above Mont Blanc and the stunning banner cloud accompanying the Matterhorn. In this last blog of the series we’ll be exploring the jaw-dropping sea of clouds.

Warm air is trapped

A sea-like cloud arises in a warm layer of air that is trapped between the cold air in the valley and the cold air in the upper layer of the sky. This is called an inversion and in such a situation, the air temperature in the mountains is higher than in the valley. Normally, this is of course the other way around.

How an inversion is formed

So how does this warm layer of air get trapped? At the end of the afternoon when the sun disappears behind the mountains, cold air descends the mountain slopes and accumulates in the valley. The warmer air in the valley will try to escape (warm air wants to rise, while the “heavier” cold air tends to drop). However, due to the colder air layer higher up in the atmosphere, the hot air gets trapped. The warmer air can no longer escape from the valley and the inversion will be stuck halfway up the mountain slopes. This is especially the case if there is now wind. During the summer a sea of clouds is mostly formed at night or early in the morning. However, in winter it can also appear during the day.

Sunscreen

If you’re hiking the Tour du Mont Blanc or the Chamonix to Zermatt Haute Route, I hope that one morning you’ll be high up in the mountains gazing over an endless sea of clouds. It’s such a spectacular panorama that you’ll remember it for the rest of your life! And if you’re lucky enough to witness this stunning cloud phenomenon, please take out your sunscreen and hat, because you can assume that it will be a bright and sunny day!

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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