Iwate city welcomes 'sea of clouds'
Tono City, Iwate Prefecture, is welcoming its annual "sea of clouds" season. The city is in a vast valley surrounded by mountains. The air chilled by radiative cooling lingers in autumn, when mornings and evenings are cold, which often creates fog. At dawn, the mist becomes a sea of clouds covering the city, glowing golden in the morning sun. The sea of clouds disappears as the sun rises and warms the air temperature.
The natural phenomenon appears every year from late September to early November depending on weather conditions. It occurs on cold, sunny days with no wind.