Mountain Clouds

Shade clouds, hanging clouds, and flag clouds have been observed to form in the vicinity of mountains. These clouds are believed to form when air currents overcome or divert over mountains. Mountain clouds are a well-known weather phenomenon among locals and weather enthusiasts.

The Kusaka Laboratory studies mountain clouds over a variety of mountains, including Mt. Fuji.

Kasa Clouds

Kasa clouds are clouds that form over the summit of an isolated peak. Although they look like shades or hats, the shape of a kasa cloud is further classified in detail. It is believed that kasa clouds form when air currents overcome a mountain.

Photo by Kusaka Lab.

Tsurushi Clouds

Tsurushi clouds occur downwind of isolated peaks and have the appearance of UFOs or wings. Hanging clouds are believed to be generated by lee waves and appear almost motionless over time.

Photo by Kusaka Lab.

Hata Clouds

Hata clouds are clouds that occur downwind of isolated peaks and look like flag or banner. Overseas, clouds known as banner clouds are known to occur on the Matterhorn and other peaks, but they are different in shape from flag clouds.

Photo by Fuji City Hall

We have installed a live camera on Mt. Fuji and are constantly monitoring the clouds.

Live camera (collaborative research with NICT)

(Written by: Kakeru Konnai; Edited by: Sharifah)

Room 301 in the Center for Computational Sciences, 1-1-1, Tennodai Tsukuba, Ibaraki 305-8577, Japan