On hotter days, why does the sky seem more grey than blue?

The sky’s bluish is owed to Rayleigh scattering — erstwhile molecules successful the aerial scatter airy of shorter wavelength (bluer) overmuch much efficiently than that of longer ones. On hotter days, however, determination tin beryllium different things successful the aerial and which tin impact however airy is scattered.

Warmer aerial tin clasp much moisture. So connected a hotter day, the aerial tin person a operation of higher humidity, successful the signifier of h2o vapour and good droplets, and much dust, aerosols, and different particulate substance that convective currents driven by the vigor person lifted up. These larger particles scatter each wavelengths of airy much equally, not conscionable blue, an effect called Mie scattering. Rayleigh scattering happens lone erstwhile the entity scattering the airy is overmuch smaller than the light’s wavelength.

As a effect of Mie scattering, the sky’s colours are ‘washed out’ into a airy grey haze.

Human cognition besides plays a tiny role. On blistery and agleam days, the wide luminance of the entity increases, forcing our eyes to adjust. So the aforesaid entity that looks bluish against a dim inheritance looks whiter erstwhile flooded with light.

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