TYNDAL EFFECT
When a ray of light pass through a colloidal fluid or suspension , the tiny particles get illuminated due to scattering. Because of this the path of the light made visible. This phenomenon is know as tyndal effect.
The intensity of the scattering depends up on the size of the particles in the medium through light passes. As the size increases the intensity of the scattering also increases.
In a misty morning the path of light is visible through the areas with dense trees, because mist is a colloid of air and water vapour. Particles in the mist is big enough to scatter the sunlight so the path of the light is visible.