sunray

A sunray is a beam of sunlight, the visible result of electromagnetic radiation emitted by the Sun that travels through space and reaches Earth. In everyday language, sunrays are the bright shafts of light that seem to stream through gaps in clouds or between objects, creating illuminated patches on the ground.

Physically, the Sun emits radiation across a broad spectrum, with a peak in the visible range due to its surface temperature of about 5,800 kelvin. Light travels at the speed of light and, by the time it reaches Earth, the rays are nearly parallel because of the Sun’s great distance. The sunray you see includes visible light as well as infrared and ultraviolet components, which are absorbed and scattered to varying degrees by the atmosphere.

At Earth, the amount of solar energy received varies with time and location. The solar constant, the irradiance at the top of the atmosphere, is about 1361 watts per square meter. After atmospheric attenuation, surface irradiance on a clear day near solar noon is typically around 1000 watts per square meter, depending on the solar zenith angle, weather, and atmospheric composition. This energy drives weather and climate and supports photosynthesis in plants, and it is harnessed in solar power systems.

Applications and considerations: sunrays influence daylighting and passive solar heating in architecture, and they are central to solar energy technologies. Excess exposure to ultraviolet components can harm skin and eyes, so sun protection is advised.