Snowflakes form inside a cloud when droplets of water freeze around tiny particles of dust, salt, bacteria or some other substance. These icy specs bump into other crystals and freeze together eventually making the flake so heavy that it begins to fall toward the ground. Snow appears to be white because visible sunlight is white and snow crystals reflect this light.
A good layer of fresh, undisturbed snow is a great insulator for plants because it is composed of a high percentage of air trapped among the lattice structure of the snow crystals. Fresh, uncompacted snow is 90-95% trapped air and since it doesn’t move the heat transfer is minimal.
When the ground has a thick layer of fresh fluffy snow, sound waves are absorbed at the surface of the snow. If the surface becomes smooth and hard as it ages or from strong winds then the surface will actually help reflect sound waves and sounds may be clearer and travel further.
Snow helps create winter interest in a garden, especially if good structural 'bones' have been created. Tall plants like the grasses pictured here continue to move in the wind, look pretty when snow laden and the seeds provide food for wildlife.