What causes cloud inversions?

Cloud inversions tend to form during periods of stable high pressure – in other words still, calm conditions. In normal circumstances, temperature generally decreases with altitude. However, during stable high pressure, that pattern is often reversed. In these situations, cold air becomes trapped in valleys and glens beneath a layer of warmer air at higher altitudes. This is a temperature inversion, but what about the cloud?

Autumn and winter are the peak cloud inversion seasons, when nights are often cold and clear. As the air cools it sinks into the valleys and glens. If there is a sufficient level of moisture in the air, a cloud layer may form as the air cools and condenses. This cloud layer will then be trapped beneath the layer of warmer air above. Therefore, a sufficient degree of moisture in the air is crucial for a cloud inversion to form. Gentle winds coming off the sea can help introduce moisture into the lower atmosphere.

SO, HOW DO YOU GO ABOUT FINDING CLOUD INVERSIONS IN PRACTICE? Here are some top tips.

1. Head to higher summits. It is quite common for only the highest summits to poke above the clouds, so the higher you climb, the greater your chances.

2. Choose prominent summits overlooking deep glens and or/large bodies of water. Low cloud and mist often forms readily above lochs, bogs and rivers. Sheltered areas surrounded by prominent summits are ideal locations for inversions to form.

3. Wild camp on a summit. Cloud inversions are most common at dawn, but can form before dusk as well.

The more time you spend on the tops, the higher your chances of success.

4. Research cloud inversion ‘hot spots’. Certain locations are quite reliable – for example, the hills overlooking Rannoch Moor, or the Munros above Loch Lochy.

5. If at first you don’t succeed, try, try again! The effort is more than worth it.