Blog: Inversions

A number of times a year it’s common to see a flurry of photos on social media from people standing on top of various summits looking down on a blanket of cloud, basking in warm sunlight. The photos are incredible but what is this and why does it happen?

The phenomenon is a temperature inversion, or simply an inversion. It’s commonly called a ‘cloud inversion’ but nit-picky people might pop up and say this is technically incorrect. To understand why inversions occur and why they’re a temperature inversion and not a cloud inversion we first need to think about the air in our atmosphere under normal conditions.

Anyone who has been up a hill of any height will probably know that it’s typically colder at the summit than at the bottom. The reason for this is that air cools as it rises. As air cools, it condenses, and this is ultimately what gives us clouds.

So how do we get inversions and how can we predict when they’ll happen? We all want to get those cool photos after all!

Inversions can be caused under a number of different conditions: calm and clear nights; under areas of high pressure; and when fronts (regions of comparatively cold or warm air) meet. What all of these have in common is that they result in colder air being ‘trapped’ under a layer of warmer air. As we’ve discussed, that isn’t what we’d typically expect to see, and hence why it’s a temperature inversion!

The great news is that if you’re lucky enough to experience this you’ll be treated to wonderful views, calm winds, and warm temperatures on your chosen summit. The bad news is that you will need to walk through clouds to get there! That means you might get a bit damp and will experience very poor visibility, so it’s important to ensure your navigation is up to scratch. The photos below were both from days that had inversions.

If you’re thinking that perhaps you could do with brushing up on your navigation or taking that first step in learning all about maps and what you can do with a compass then check out our navigation classes here.

If you want to learn a bit more about weather and how it impacts our decision making and planning for days on the hills then why not come along to one of our Mountaincraft Skills Days.

Hope to see you on the hill soon,

Jack