Clouds allow some ultraviolet (UV) light to pass through, similar to how they permit visible light, which is why visibility remains on cloudy days. While clouds block a significant portion of UV radiation, they do not completely eliminate it, leading to potential skin damage despite overcast conditions. The discussion highlights the misconception that cloudy weather provides full protection from UV rays. This phenomenon is reflected in cultural references, such as the song "My Girl," which captures the idea of finding brightness even when the sky is cloudy. Understanding the effects of clouds on UV exposure is crucial for skin protection.