When are the two clouds overlapping?

The icon of two white clouds is cloudy weather.

Cloudy, in meteorology, means that the cloud coverage in the sky accounts for four to eight tenths of the sky. Be careful of ultraviolet rays when you are active in cloudy weather. Ultraviolet ray is the general name of radiation with the wavelength from 10 nm to 400 nm in the electromagnetic spectrum, which can't be detected by human eyes, but too much ultraviolet ray may harm eyes.