The Compass Blog

How to Read a Cloud (What You Don’t Know Could Kill You)

There’s nothing quite like watching a summer thunderstorm roll through from the relative safety of one’s front porch. But if that same thunderstorm catches you out on an open scree slope at 10,000 feet, it can turn into a life and death situation.  If you’re going to be spending time outdoors this summer – hiking, camping, backpacking, climbing, cycling, kayaking, the list goes on and on – it’s a very good idea to learn how to read the clouds so you can learn which clouds are harbingers of storms.

Clouds come in all sizes, shapes, and shades. Here are a few to keep an eye out for while you’re out adventuring this summer.

Cumulonimbus clouds – Who doesn’t love the big, white, puffy, floating cumulus clouds? But pay attention when the tops of the cumulus clouds start to grow upwards and resemble Cauliflower. That’s called cumulus congestus or towering cumulus. These clouds grow upward, and they can develop into a giant cumulonimbus. If the base of these towering cumulus clouds grow dark, they have become cumulonimbus clouds. The condensation of water vapor within the cloud releases tremendous amounts of energy and creates lightning, thunder, and even violent tornadoes. So when you’re out exploring and you notice towering cumulus clouds, start thinking about your next moves.

Anvil clouds – An anvil cloud (Cumulonimbus incus) is made of ice particles. These frozen particles form in the highest levels of cumulonimbus clouds. The anvil, flat top shape is produced by the rising air. It expands and spreads out as the air hits the bottom of the stratosphere. Sometimes, these thunderstorm tops can be seen over 100 miles away! And pay attention – if you notice clouds that look like they’re pushing through the flat top or appear to bubble up out of it, that’s known as the overshooting top, and is a sign that a storm is getting stronger.

Wall clouds – This type of cloud forms abruptly from the bottom of a cumulonimbus cloud. it’s like an ‘accessory’ cloud, and they’re big – normally a kilometer or more in diameter. The wall cloud marks the lower portion of a very strong updraft and is usually associated with a supercell or multicell storm. Wall clouds that exhibit significant rotation and vertical motions often precede tornados by a few minutes to an hour. So if you’re spending your summer in the tornado region of the country, it’s especially important to learn how to read these dangerous clouds.

Lenticular clouds – Lastly, lenticular clouds are just plain cool to see. They’re not a warning cloud for storms, but indicate warmer and windier weather. These clouds are so named because they look like a lens, sometimes one on top of the other, and are seemingly stable, with a motionless appearance. However, lenticular clouds indicate great instability in the layer of the atmosphere where they form. They are often a marker of air currents like waves bouncing over the mountains. You’ll probably see some lenticular clouds this summer while you’re hiking at higher elevations.

Learning how to read a cloud can help you identify when it’s time to turn back from a summit push, get off the river, find shelter off the trail, and just keep you safe and empowered to make smart decisions in all of your outdoor pursuits. Be safe and have fun out there as you dance among the clouds!

“May your trails be crooked, winding, lonesome, dangerous, leading to the most amazing view. May your mountains rise into and above the clouds.” ~ Edward Abbey

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