The Physics of Light: What Is Light? Why is sunlight so hot while the tube light light's hardly warm. Sunlight. The ultraviolet B component of sunlight on the skin is an effective source of vitamin D3 (cholecalciferol) from serum cholesterol.
Summary[edit] Sunlight may be recorded using a sunshine recorder, pyranometer, or pyrheliometer. Sunlight takes about 8.3 minutes to reach the Earth from the surface of the Sun.