The colour of Baikal's water is close to that of
the sea. It is a similar dark blue, blue-green, aquamarine, "the colours of the desert",
"the colours of seaweed". Even along the shore, in the shallows, it is blue-green. This
colour is the result of its optical purity which is brought about by its minute content
of dissolved and suspended particles.
The colour of Baikal water depends on the scattering and absorption of rays of light. In
optically pure water the short wave blue rays are scattered more, and the long wave
red rays less. A large part of the blue rays at depths are reflected by water molecules towards the surface. These rays are not absorbed well and reach
the surface with the least loss. It is these that determine the colour of water. Water
gets its green colour from the green part of the spectrum when they begin to predominate
over the blue, whose penetration into the depths becomes hindered by suspended particles
in the water.
The color of Baikal water changes with time. Baikal is sometimes blue-green and
aquamarine in early spring immediately after the ice has cleared. In summer, especially
in August it becomes bright green because of the mass growth of diatoms and blue-green
algae. At this time local people say that "Baikal is in bloom!" In autumn, it is largely
a gloomy, dark grey as a result of cloudy skies and mists that lower the illumination of
the water surface, and because of winds and storms mixing the surface waters.
The color of Baikal water differs from area to area in Baikal. The water in the open part
of the lake is usually dark blue. Near the mouth of the river Selenga it is greyish-green
and even brown and dark brown, as the river carries with it sediment and suspended
At a distance, the colour of the lake's surface is changeable: now green, now blue, then
grey, mother-of-pearl or iridescent. This was noted by the Irkutsk poet Ivan
I.Molchanov-Sibirsky: "Every moment changes its colour - silvery, orange, scarlet - the
magician of ancient tales, the magician, Baikal." The receptivity of the colour of the
lake waters surface depends on the state of the sky and colouring of the clouds - the
element of air is reflected in the element of water.