The phenomenon that causes the scattering of light in the atmosphere is known as Rayleigh scattering. This scattering occurs when sunlight interacts with small particles and gas molecules in the atmosphere, causing shorter wavelengths (blue light) to scatter more than longer wavelengths (red light). This effect explains the blue appearance of the sky during the day and the reddish hues observed during sunrise and sunset. Understanding Rayleigh scattering is essential in fields like meteorology and optics.