What visual effect do distant aircraft typically present?

Distant aircraft typically present a bluish and blurry appearance due to a combination of atmospheric effects, such as air density and particles in the atmosphere. As light passes through the atmosphere, especially over longer distances, it scatters. This scattering is more pronounced for shorter wavelengths of light, which are in the blue spectrum. Consequently, when viewing an aircraft that is far away, this scattering can cause it to take on a bluish tint. Additionally, atmospheric particles, moisture, and haze contribute to making distant objects appear less defined, resulting in a blurry, indistinct outline. This combination of effects means that not only do these aircraft appear bluish, but they also lack the clarity one would expect at closer ranges, making them appear blurry.