There's no risk of animals or bad weather interfering with your campsite, either. You don't even really need a tent. A sleeping pad, sleeping bag and a mindful eye to pick up everything you brought in is all you really need to enjoy overnight caving. Do your research
I believe it’s because of the air from the lower part of the mountain adjusting to the climate at the top. Mountains cause air to rise, and when that air rises it cools down creating the clouds.