Such is their popularity on Instagram that when you dive into the deep pool of cloud-related hashtags you can choose not just from #cloud #clouds, and #cloudysky but also #cloudscape, #cloudstagram, and #cloudporn (which is slightly, though not overwhelmingly, NSFW).
You’d think big ol’ puffy cumulonimbuses (cumulonimbi?) would dominate things, but it turns out people are really into stratus clouds. Maybe it has to do with the way they can often give way to fog or precede a storm, but something about stratus clouds apparently says, “Throw a filter on me.”
Stratus clouds are low-level clouds that form when blowing wind hits a physical obstacle — like the side of a mountain — and is forced upward accordingly. The warm air moves higher into the atmosphere, becomes depressurized and cools, and a (flat, stretchy, possibly bumpy) cloud is born. They’re not dissimilar from fog in this sense.
Stratus clouds can cover the entire sky, sheet-like, but the patchier-looking ones can still be stratus clouds under the right conditions. Their frequent proximity to mountain ranges might provide a partial explanation for their popularity on Instagram — all those hikers and campers and families over-sharing their ski vacations — but they’re also just nice to look at.
That repetitive, blanket-like quality that makes them so mesmerizing and attractive to photograph is inherent to what makes a stratus cloud a stratus cloud. Then there are the different subsets: cirrostratus, altostratus, nimbostratus, and stratocumulus. These differ in thickness and altitude. A cirrostratus cloud, for example, is wispier and thinner, more transclucent, while stratocumulus are those lumpy, bumpy-looking ones.
Though they’re often accompanied by fog and rain, they themselves don’t really produce much heavy precipitation, just drizzles. If you’re one of those people super into Instagramming these (or any other type of clouds), know that there is in fact an entire Cloud Appreciation Society of like-minded, stratus-loving people.