As of today, in season now. Earth Exhibit tracks the live conditions and flags it the moment it is on.
Asperitas is the youngest formation in the meteorological canon: a chaotic, wave-tossed cloud underside that the World Meteorological Organization added to the International Cloud Atlas in March 2017 — the first new entry of its kind in decades.
It is classified as a supplementary feature occurring mostly with stratocumulus and altocumulus, and the WMO describes localized waves in the cloud base, smooth or dappled, sometimes descending into sharp points, as if you were looking up at a roughened sea surface from beneath the waves.
The name comes from the Latin for 'roughness.' Its recognition is a citizen-science story: photographs from the public, championed by the Cloud Appreciation Society and a key 2006 image from Cedar Rapids, Iowa, built the case for a brand-new classification.
Asperitas is rare and fleeting — often appearing in disturbed, moisture-laden air, frequently in the warm season and in the wake of thunderstorms, and usually dissolving within minutes to an hour without ever producing a storm itself.
Where to see it
A taste of where to see it. The full map, exact coordinates and the best timing for each spot live in the app.
| Viewing spots |
|---|
| Cedar Rapids area, Iowa (upper Midwest) |
| Lincoln area, southeast Nebraska (Great Plains) |
| + 1 more spot, with exact coordinates and timing, in the app → |
This is the short version
This page shows a taste. The app has the full list of where to see this, the exact timing, and live conditions for 1,000+ natural phenomena worldwide, so you know the moment one is genuinely worth the trip.