Why is it difficult to see through fog?

It is difficult to see through fog primarily because rays of light are scattered by the fog droplets. Fog consists of tiny water droplets that condense on fine dust particles near the ground [c2][c3]. When light encounters these droplets, it undergoes a phenomenon known as Mie scattering [t6][t7]. Unlike Rayleigh scattering, which affects shorter wavelengths, Mie scattering occurs when the particle size is comparable to or larger than the wavelength of visible light, causing light to scatter in multiple directions [t1][t7]. This scattering attenuates light intensity and changes its path, which significantly reduces horizontal visibility to less than one kilometer [c3][t5]. Because fog droplets scatter all visible wavelengths almost equally, the fog appears as a thick, whitish, or grayish opaque barrier that prevents clear vision [c1][t7]. While some absorption occurs, scattering is the dominant factor in visibility reduction [t5][t9].

Sources

1. [1] Science , class X (NCERT 2025 ed.) > Chapter 10: The Human Eye and the Colourful World > 10.6.1 Tyndall Effect > p. 169
2. [2] FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Geography Class XI (NCERT 2025 ed.) > Chapter 10: Water in the Atmosphere > Fog and Mist > p. 87
3. [3] Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 24: Hydrological Cycle (Water Cycle) > Fog > p. 332
4. [4] https://www.ipcc.ch/site/assets/uploads/2018/03/TAR-05.pdf